Merge branch 'bug_197989_B'

91 files changed, 4346 insertions, 1770 deletions

diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/DOMLocationInclusionTests.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/DOMLocationInclusionTests.java
index ddc284ea9ba..82846d56284 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/DOMLocationInclusionTests.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/DOMLocationInclusionTests.java
@@ -1,13 +1,13 @@
 /*******************************************************************************
- * Copyright (c) 2004, 2008 IBM Corporation and others.
+ * Copyright (c) 2004, 2011 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
- * IBM - Initial API and implementation
- * Markus Schorn (Wind River Systems)
+ *    IBM - Initial API and implementation
+ *    Markus Schorn (Wind River Systems)
  *******************************************************************************/
 package org.eclipse.cdt.core.parser.tests.ast2;
 
@@ -35,6 +35,7 @@ import org.eclipse.cdt.core.parser.ExtendedScannerInfo;
 import org.eclipse.cdt.core.parser.IExtendedScannerInfo;
 import org.eclipse.cdt.core.parser.IScannerInfo;
 import org.eclipse.cdt.core.parser.ParserLanguage;
+import org.eclipse.cdt.core.parser.ScannerInfo;
 import org.eclipse.cdt.internal.core.dom.SavedCodeReaderFactory;
 import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IProject;
@@ -70,9 +71,9 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
         String code = "int main() { return BEAST * sizeof( Include ); } "; //$NON-NLS-1$
         for (ParserLanguage p : ParserLanguage.values()) {
             String filename = (p == ParserLanguage.CPP) ? "main.cc" : "main.c"; //$NON-NLS-1$ //$NON-NLS-2$
-            IFile c = importFile(filename, code); //$NON-NLS-1$ //$NON-NLS-2$
+            IFile c = importFile(filename, code); 
 
-            IASTTranslationUnit tu = parse(c, scannerInfo); //$NON-NLS-1$
+            IASTTranslationUnit tu = parse(c, scannerInfo); 
             IASTFunctionDefinition fd = (IASTFunctionDefinition) tu.getDeclarations()[3];
             IASTFileLocation floc = fd.getFileLocation();
             assertEquals(floc.getNodeOffset(),
@@ -102,11 +103,11 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
 
             for (ParserLanguage p : ParserLanguage.values()) {
                 String filename = (p == ParserLanguage.CPP) ? "blah.cc" : "blah.c"; //$NON-NLS-1$ //$NON-NLS-2$
-                IFile source = importFile(filename, code); //$NON-NLS-1$
-                IASTTranslationUnit tu = parse(source); //$NON-NLS-1$
+                IFile source = importFile(filename, code); 
+                IASTTranslationUnit tu = parse(source); 
                 IASTSimpleDeclaration declaration = (IASTSimpleDeclaration) tu.getDeclarations()[0];
                 assertSoleFileLocation(declaration.getDeclarators()[0], filename,
-                        code.indexOf("SomeStructure"), "SomeStructure".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+                        code.indexOf("SomeStructure"), "SomeStructure".length()); //$NON-NLS-1$ //$NON-NLS-2$ 
             }
         }
     }
@@ -206,13 +207,13 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
 
         for (ParserLanguage p : ParserLanguage.values()) {
             String filename = (p == ParserLanguage.CPP) ? "code.cc" : "code.c"; //$NON-NLS-1$ //$NON-NLS-2$
-            IFile cpp = importFile(filename, code); //$NON-NLS-1$
-            IASTTranslationUnit tu = parse(cpp); //$NON-NLS-1$
+            IFile cpp = importFile(filename, code); 
+            IASTTranslationUnit tu = parse(cpp); 
             IASTDeclaration[] declarations = tu.getDeclarations();
             assertEquals(declarations.length, 2);
             IASTSimpleDeclaration bar = (IASTSimpleDeclaration) declarations[0];
             IASTSimpleDeclaration FOO = (IASTSimpleDeclaration) declarations[1];
-            assertSoleFileLocation(bar, filename, code.indexOf("int"), code.indexOf(";") + 1); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+            assertSoleFileLocation(bar, filename, code.indexOf("int"), code.indexOf(";") + 1); //$NON-NLS-1$ //$NON-NLS-2$ 
 
             assertSoleFileLocation(FOO, "foo.h", foo.indexOf("int"), foo.indexOf(";") + 1); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
             IASTPreprocessorIncludeStatement[] incs = tu.getIncludeDirectives();
@@ -243,8 +244,8 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
 
         for (ParserLanguage p : ParserLanguage.values()) {
             String filename = (p == ParserLanguage.CPP) ? "code.cc" : "code.c"; //$NON-NLS-1$ //$NON-NLS-2$
-            IFile cpp = importFile(filename, code); //$NON-NLS-1$
-            IASTTranslationUnit tu = parse(cpp); //$NON-NLS-1$
+            IFile cpp = importFile(filename, code); 
+            IASTTranslationUnit tu = parse(cpp); 
             IASTDeclaration[] declarations = tu.getDeclarations();
             assertEquals(declarations.length, 3);
             IASTSimpleDeclaration bar = (IASTSimpleDeclaration) declarations[0];
@@ -253,21 +254,21 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
             assertSoleFileLocation(
                     bar,
                     filename,
-                    code.indexOf("int"), code.indexOf("r;") + 2 - code.indexOf("int")); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
+                    code.indexOf("int"), code.indexOf("r;") + 2 - code.indexOf("int")); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ 
             assertSoleFileLocation(
                     FOO,
                     "foo.h", foo.indexOf("int"), foo.indexOf(";") + 1 - foo.indexOf("int")); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
             assertSoleFileLocation(
                     byob,
                     filename,
-                    code.indexOf("float"), code.indexOf("b;") + 2 - code.indexOf("float")); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
+                    code.indexOf("float"), code.indexOf("b;") + 2 - code.indexOf("float")); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ 
             IASTPreprocessorIncludeStatement[] incs = tu.getIncludeDirectives();
             assertNotNull(incs);
             assertEquals(incs.length, 1);
             assertSoleFileLocation(
                     incs[0],
                     filename,
-                    code.indexOf("#inc"), code.indexOf(".h\"\n") + ".h\"".length() - code.indexOf("#inc")); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ //$NON-NLS-5$
+                    code.indexOf("#inc"), code.indexOf(".h\"\n") + ".h\"".length() - code.indexOf("#inc")); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ 
         }
     }
 
@@ -278,8 +279,8 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
 
         for (ParserLanguage p : ParserLanguage.values()) {
             String filename = (p == ParserLanguage.CPP) ? "blah.cc" : "blah.c"; //$NON-NLS-1$ //$NON-NLS-2$
-            IFile c_file = importFile(filename, c_file_code); //$NON-NLS-1$    
-            IASTTranslationUnit tu = parse(c_file); //$NON-NLS-1$
+            IFile c_file = importFile(filename, c_file_code); 
+            IASTTranslationUnit tu = parse(c_file); 
             assertEquals(tu.getDeclarations().length, 0);
             IASTPreprocessorMacroDefinition[] macroDefinitions = tu
                     .getMacroDefinitions();
@@ -288,9 +289,9 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
             assertSoleFileLocation(
                     macroDefinitions[0],
                     filename,
-                    c_file_code.indexOf("#define"), c_file_code.indexOf("4") + 1 - c_file_code.indexOf("#define")); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
+                    c_file_code.indexOf("#define"), c_file_code.indexOf("4") + 1 - c_file_code.indexOf("#define")); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ 
             assertSoleFileLocation(macroDefinitions[0].getName(), filename,
-                    c_file_code.indexOf("X"), 1); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
+                    c_file_code.indexOf("X"), 1); //$NON-NLS-1$ 
             assertSoleFileLocation(
                     macroDefinitions[1],
                     "blarg.h", h_file_code.indexOf("#define _BLARG_H_"), "#define _BLARG_H_".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
@@ -299,17 +300,17 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
                     "blarg.h", h_file_code.indexOf("e _BLARG_H_") + 2, "_BLARG_H_".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
             assertSoleFileLocation(
                     macroDefinitions[2],
-                    "blarg.h", h_file_code.indexOf("#define PRINT(s,m)  printf(s,m)\r"), "#define PRINT(s,m)  printf(s,m)".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
+                    "blarg.h", h_file_code.indexOf("#define PRINT(s,m)  printf(s,m)\r"), "#define PRINT(s,m)  printf(s,m)".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ 
             assertSoleFileLocation(macroDefinitions[2].getName(),
-                    "blarg.h", h_file_code.indexOf("PRINT"), "PRINT".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
+                    "blarg.h", h_file_code.indexOf("PRINT"), "PRINT".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ 
             assertSoleFileLocation(
                     macroDefinitions[3],
                     filename,
-                    c_file_code.indexOf("#define POST_INCLUDE"), "#define POST_INCLUDE".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+                    c_file_code.indexOf("#define POST_INCLUDE"), "#define POST_INCLUDE".length()); //$NON-NLS-1$ //$NON-NLS-2$ 
             assertSoleFileLocation(
                     macroDefinitions[3].getName(),
                     filename,
-                    c_file_code.indexOf("POST_INCLUDE"), "POST_INCLUDE".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+                    c_file_code.indexOf("POST_INCLUDE"), "POST_INCLUDE".length()); //$NON-NLS-1$ //$NON-NLS-2$ 
         }
     }
 
@@ -322,7 +323,7 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
 
         for (ParserLanguage p : ParserLanguage.values()) {
             String filename = (p == ParserLanguage.CPP) ? "source.cc" : "source.c"; //$NON-NLS-1$ //$NON-NLS-2$
-            IFile f = importFile(filename, cpp_code); //$NON-NLS-1$
+            IFile f = importFile(filename, cpp_code); 
             IASTTranslationUnit tu = parse(f);
             IASTDeclaration[] declarations = tu.getDeclarations();
             IASTPreprocessorIncludeStatement[] includeDirectives = tu
@@ -330,7 +331,7 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
             assertSoleFileLocation(
                     includeDirectives[0],
                     filename,
-                    cpp_code.indexOf("#include \"header1.h\""), "#include \"header1.h\"".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+                    cpp_code.indexOf("#include \"header1.h\""), "#include \"header1.h\"".length()); //$NON-NLS-1$ //$NON-NLS-2$ 
             assertSoleFileLocation(declarations[0],
                     "header1.h", 0, "int x;".length()); //$NON-NLS-1$ //$NON-NLS-2$
             assertSoleFileLocation(declarations[1],
@@ -338,9 +339,9 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
             assertSoleFileLocation(
                     includeDirectives[1],
                     filename,
-                    cpp_code.indexOf("#include \"header2.h\""), "#include \"header2.h\"".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+                    cpp_code.indexOf("#include \"header2.h\""), "#include \"header2.h\"".length()); //$NON-NLS-1$ //$NON-NLS-2$ 
             assertSoleFileLocation(declarations[2], filename, cpp_code
-                    .indexOf("int z;"), "int z;".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+                    .indexOf("int z;"), "int z;".length()); //$NON-NLS-1$ //$NON-NLS-2$ 
 
             IASTTranslationUnit.IDependencyTree tree = tu.getDependencyTree();
             assertEquals(tree.getInclusions().length, 2);
@@ -357,8 +358,8 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
 
         for (ParserLanguage p : ParserLanguage.values()) {
             String filename = (p == ParserLanguage.CPP) ? "blah.cc" : "blah.c"; //$NON-NLS-1$ //$NON-NLS-2$
-            IFile c_file = importFile(filename, c_file_code); //$NON-NLS-1$
-            IASTTranslationUnit tu = parse(c_file); //$NON-NLS-1$
+            IFile c_file = importFile(filename, c_file_code); 
+            IASTTranslationUnit tu = parse(c_file); 
             assertEquals(tu.getDeclarations().length, 0);
             IASTPreprocessorMacroDefinition[] macroDefinitions = tu.getMacroDefinitions();
             assertNotNull(macroDefinitions);
@@ -366,9 +367,9 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
             assertSoleFileLocation(
                     macroDefinitions[0],
                     filename,
-                    c_file_code.indexOf("#define"), c_file_code.indexOf("4") + 1 - c_file_code.indexOf("#define")); //$NON-NLS-1$ //$NON-NLS-2$    //$NON-NLS-3$ //$NON-NLS-4$
+                    c_file_code.indexOf("#define"), c_file_code.indexOf("4") + 1 - c_file_code.indexOf("#define")); //$NON-NLS-1$ //$NON-NLS-2$    //$NON-NLS-3$ 
             assertSoleFileLocation(macroDefinitions[0].getName(), filename,
-                    c_file_code.indexOf("X"), 1); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$    //$NON-NLS-4$
+                    c_file_code.indexOf("X"), 1); //$NON-NLS-1$ 
             assertSoleFileLocation(
                     macroDefinitions[1],
                     "blarg.h", h_file_code.indexOf("#define _BLARG_H_"), "#define _BLARG_H_".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
@@ -377,24 +378,24 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
                     "blarg.h", h_file_code.indexOf("e _BLARG_H_") + 2, "_BLARG_H_".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
             assertSoleFileLocation(
                     macroDefinitions[2],
-                    "blarg.h", h_file_code.indexOf("#define PRINT(s,m) printf(s,m)\r"), "#define PRINT(s,m) printf(s,m)".length()); //$NON-NLS-1$ //$NON-NLS-2$    //$NON-NLS-3$ //$NON-NLS-4$
+                    "blarg.h", h_file_code.indexOf("#define PRINT(s,m) printf(s,m)\r"), "#define PRINT(s,m) printf(s,m)".length()); //$NON-NLS-1$ //$NON-NLS-2$    //$NON-NLS-3$ 
             assertSoleFileLocation(macroDefinitions[2].getName(),
-                    "blarg.h", h_file_code.indexOf("PRINT"), "PRINT".length()); //$NON-NLS-1$    //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
+                    "blarg.h", h_file_code.indexOf("PRINT"), "PRINT".length()); //$NON-NLS-1$    //$NON-NLS-2$ //$NON-NLS-3$ 
             assertSoleFileLocation(
                     macroDefinitions[3],
                     filename,
-                    c_file_code.indexOf("#define POST_INCLUDE"), "#define POST_INCLUDE".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+                    c_file_code.indexOf("#define POST_INCLUDE"), "#define POST_INCLUDE".length()); //$NON-NLS-1$ //$NON-NLS-2$ 
             assertSoleFileLocation(
                     macroDefinitions[3].getName(),
                     filename,
-                    c_file_code.indexOf("POST_INCLUDE"), "POST_INCLUDE".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+                    c_file_code.indexOf("POST_INCLUDE"), "POST_INCLUDE".length()); //$NON-NLS-1$ //$NON-NLS-2$ 
             assertSoleFileLocation(
                     macroDefinitions[4],
                     "second.h", h_file2_code.indexOf("#define _SECOND_H_"), "#define _SECOND_H_".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
             assertSoleFileLocation(
                     macroDefinitions[5],
                     filename,
-                    c_file_code.indexOf("#define POST_SECOND"), "#define POST_SECOND".length()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$    //$NON-NLS-4$
+                    c_file_code.indexOf("#define POST_SECOND"), "#define POST_SECOND".length()); //$NON-NLS-1$ //$NON-NLS-2$ 
 
         }
     }
@@ -411,15 +412,15 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
         buffer.append("};\n"); //$NON-NLS-1$
         buffer.append("#endif /*_INCLUDE_H_*/\n"); //$NON-NLS-1$
         final String inc_file_code = buffer.toString();
-        IFile include_file = importFile("include.h", inc_file_code); //$NON-NLS-1$ //$NON-NLS-2$
+        IFile include_file = importFile("include.h", inc_file_code); //$NON-NLS-1$ 
         String[] macros = { imacro_file.getLocation().toOSString() };
         String[] includes = { include_file.getLocation().toOSString() };
         IExtendedScannerInfo scannerInfo = new ExtendedScannerInfo(Collections.EMPTY_MAP, EMPTY_STRING_ARRAY, macros, includes);
         
         for (ParserLanguage p : ParserLanguage.values()) {
             String filename = (p == ParserLanguage.CPP) ? "main.cc" : "main.c"; //$NON-NLS-1$ //$NON-NLS-2$
-            IFile code = importFile(filename, "int main() { return BEAST * sizeof( Include ); } "); //$NON-NLS-1$ //$NON-NLS-2$
-            IASTTranslationUnit tu = parse(code, scannerInfo); //$NON-NLS-1$
+            IFile code = importFile(filename, "int main() { return BEAST * sizeof( Include ); } "); //$NON-NLS-1$ 
+            IASTTranslationUnit tu = parse(code, scannerInfo); 
             IASTPreprocessorMacroDefinition[] macro_defs = tu.getMacroDefinitions();
             assertEquals(macro_defs.length, 2);
             IASTPreprocessorMacroDefinition BEAST = macro_defs[0];
@@ -443,8 +444,8 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
 
         for (ParserLanguage p : ParserLanguage.values()) {
             String filename = (p == ParserLanguage.CPP) ? "blah.cc" : "blah.c"; //$NON-NLS-1$ //$NON-NLS-2$
-            IFile f = importFile(filename, code); //$NON-NLS-1$
-            IASTTranslationUnit tu = parse(f); //$NON-NLS-1$
+            IFile f = importFile(filename, code); 
+            IASTTranslationUnit tu = parse(f); 
             IASTProblem[] prbs = tu.getPreprocessorProblems();
             assertEquals(prbs.length, 1);
             IASTNodeLocation[] locs = prbs[0].getNodeLocations();
@@ -474,16 +475,16 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
         buffer.append("};\n"); //$NON-NLS-1$
         buffer.append("#endif /*_INCLUDE_H_*/\n"); //$NON-NLS-1$
         final String inc_file_code = buffer.toString();
-        IFile include_file = importFile("include.h", inc_file_code); //$NON-NLS-1$ //$NON-NLS-2$
+        IFile include_file = importFile("include.h", inc_file_code); //$NON-NLS-1$ 
         String[] macros = { imacro_file.getLocation().toOSString() };
         String[] includes = { include_file.getLocation().toOSString() };
         IExtendedScannerInfo scannerInfo = new ExtendedScannerInfo(
                 Collections.EMPTY_MAP, EMPTY_STRING_ARRAY, macros, includes);
         for (ParserLanguage p : ParserLanguage.values()) {
             String filename = (p == ParserLanguage.CPP) ? "main.cc" : "main.c"; //$NON-NLS-1$ //$NON-NLS-2$
-            IFile code = importFile(filename, "int main() { return BEAST * sizeof( Include ); } "); //$NON-NLS-1$ //$NON-NLS-2$
+            IFile code = importFile(filename, "int main() { return BEAST * sizeof( Include ); } "); //$NON-NLS-1$ 
 
-            IASTTranslationUnit tu = parse(code, scannerInfo); //$NON-NLS-1$
+            IASTTranslationUnit tu = parse(code, scannerInfo); 
             IASTPreprocessorMacroDefinition[] macro_defs = tu.getMacroDefinitions();
             assertEquals(macro_defs.length, 4);
             IASTPreprocessorMacroDefinition BEAST = macro_defs[0];
@@ -515,14 +516,14 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
         buffer.append("};\n"); //$NON-NLS-1$
         buffer.append("#endif /*_INCLUDE_H_*/\n"); //$NON-NLS-1$
         final String inc_file_code = buffer.toString();
-        IFile include_file = importFile("include.h", inc_file_code); //$NON-NLS-1$ //$NON-NLS-2$
+        IFile include_file = importFile("include.h", inc_file_code); //$NON-NLS-1$ 
         String[] macros = { imacro_file1.getLocation().toOSString(), imacro_file2.getLocation().toOSString() };
         String[] includes = { include_file.getLocation().toOSString() };
         IExtendedScannerInfo scannerInfo = new ExtendedScannerInfo(Collections.EMPTY_MAP, EMPTY_STRING_ARRAY, macros, includes);
         
         for (ParserLanguage p : ParserLanguage.values()) {
             String filename = (p == ParserLanguage.CPP) ? "main.cc" : "main.c"; //$NON-NLS-1$ //$NON-NLS-2$
-            IFile code = importFile(filename, "int main() { return BEAST * sizeof( Include ); } "); //$NON-NLS-1$ //$NON-NLS-2$
+            IFile code = importFile(filename, "int main() { return BEAST * sizeof( Include ); } "); //$NON-NLS-1$ 
 
             IASTTranslationUnit tu = parse(code, scannerInfo); 
             IASTPreprocessorMacroDefinition[] macro_defs = tu.getMacroDefinitions();
@@ -611,4 +612,182 @@ public class DOMLocationInclusionTests extends AST2FileBasePluginTest {
     		tmpFile.getParentFile().delete();
     	}
     }
+    
+    // // comment
+    //  
+    // #ifndef guard
+    // #define guard
+    //  bla bla
+    // #if 1
+    // #endif
+    //  bla bla
+    // #endif
+    // //comment
+
+    // // comment
+    //  
+    // #if !defined(guard)
+    // #define guard
+    //  bla bla
+    // #if 1
+    // #endif
+    //  bla bla
+    // #endif
+    // //comment
+
+    // // comment
+    //  
+    // #if ((!defined guard))
+    // #define guard
+    //  bla bla
+    // #if 1
+    // #endif
+    //  bla bla
+    // #endif
+    // //comment
+    
+    // // comment
+    // #pragma once
+    
+    //    // Some comment
+    //
+    //    #ifndef AN_UNIQUE_INCLUDE_GUARD_H_
+    //    #define AN_UNIQUE_INCLUDE_GUARD_H_
+    //
+    //    #include <string>
+    //
+    //    Some code without any macro references
+    //
+    //    #endif  // AN_UNIQUE_INCLUDE_GUARD_H_
+    public void testPragmaOnceDetection_197989a() throws Exception {    
+    	CharSequence[] contents= getContents(5);
+    	
+    	int i= 0;
+    	for (CharSequence content : contents) {
+    		String headerName = i + ".h";
+			IFile base = importFile("base" + headerName, "#include \"" + headerName + "\"");
+    		importFile(headerName, content.toString());
+			IASTTranslationUnit tu = parse(base, new ScannerInfo()); 
+			IASTPreprocessorIncludeStatement[] incs = tu.getIncludeDirectives();
+			assertTrue(incs.length > 0);
+			assertTrue(incs[0].hasPragmaOnceSemantics());
+		}
+    }
+
+    // #ifndef guard
+    // #define guard2
+    // #endif
+
+    // #if !defined guard
+    // #define guard2
+    // #endif
+
+    // #if !defined(guard) && !defined(guard2)
+    // #define guard
+    // #endif
+
+    // #if (0)
+    // #pragma once
+    // #endif
+
+    // leading
+    // #ifndef guard
+    // #define guard2
+    // #endif
+
+    // #ifndef guard
+    // #define guard2
+    // #endif
+    // #ifdef xx
+    // trailing
+    // #endif
+    public void testPragmaOnceDetection_197989b() throws Exception {    
+    	CharSequence[] contents= getContents(6);
+    	
+    	int i= 0;
+    	for (CharSequence content : contents) {
+    		String headerName = i + ".h";
+			IFile base = importFile("base" + headerName, "#include \"" + headerName + "\"");
+    		importFile(headerName, content.toString());
+			IASTTranslationUnit tu = parse(base, new ScannerInfo()); 
+			IASTPreprocessorIncludeStatement[] incs = tu.getIncludeDirectives();
+			assertEquals(1, incs.length);
+			assertFalse(incs[0].hasPragmaOnceSemantics());
+		}
+    }
+    
+    
+    // // header.h
+    // #ifdef AH
+    // #endif
+    // #ifndef BH 
+    // #endif
+    // #define h
+    // #if CH || DH
+    // #elif EH==1
+    // #endif
+    
+    // #define BH
+    // #define DH 0
+    // #define EH 1
+    // #include "header.h"
+    // #ifdef h // defined in header
+    // #endif
+    // #ifdef A 
+    //    #ifdef a  // inactive
+    //    #endif
+    // #else
+    //   #ifndef B	 
+    //   #endif
+    // #endif
+    // #if defined C
+    // #elif ((!((defined(D)))))
+    // #endif
+    // #define A
+    // #define B
+    // #define AH
+    // #define h
+    // #undef u
+    // #ifdef h  // locally defined
+    // #endif    
+    // #ifndef u // locally undefined
+    // #endif
+    public void testSignificantMacros_197989a() throws Exception {    
+    	CharSequence[] contents= getContents(2);
+
+    	IFile h = importFile("header.h", contents[0].toString());
+    	IFile c = importFile("source.c", contents[1].toString());
+
+    	IASTTranslationUnit tu = parse(c, new ScannerInfo()); 
+    	IASTPreprocessorIncludeStatement[] incs = tu.getIncludeDirectives();
+    	assertEquals(1, incs.length);
+    	assertEquals("{AH=null,BH=*,CH=null,DH=0,EH=1}",
+    			incs[0].getSignificantMacros().toString());
+    	assertEquals("{A=null,AH=null,B=null,C=null,CH=null,D=null}",
+    			tu.getSignificantMacros().toString());
+    }
+    
+    // // header.h
+    // #if EQ(A,B)
+    // #endif
+    
+    // #define EQ(x,y) x==y
+    // #define A A1
+    // #define B 1
+    // #include "header.h"
+        public void testSignificantMacros_197989b() throws Exception {    
+    	CharSequence[] contents= getContents(2);
+
+    	IFile h = importFile("header.h", contents[0].toString());
+    	IFile c = importFile("source.c", contents[1].toString());
+
+    	IASTTranslationUnit tu = parse(c, new ScannerInfo()); 
+    	IASTPreprocessorIncludeStatement[] incs = tu.getIncludeDirectives();
+    	assertEquals(1, incs.length);
+    	assertEquals("{A=A1,A1=null,B=1,EQ=x==y}",
+    			incs[0].getSignificantMacros().toString());
+    	assertEquals("{A1=null}",
+    			tu.getSignificantMacros().toString());
+    }
+
 }
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/scanner/FileCodeReaderFactory.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/scanner/FileCodeReaderFactory.java
index 3668c5dcd15..b84db415e89 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/scanner/FileCodeReaderFactory.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/scanner/FileCodeReaderFactory.java
@@ -1,29 +1,29 @@
 /*******************************************************************************
- * Copyright (c) 2004, 2009 IBM Corporation and others.
+ * Copyright (c) 2004, 2011 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
- *    IBM - Initial API and implementation
+ *     IBM - Initial API and implementation
  *******************************************************************************/
 package org.eclipse.cdt.core.parser.tests.scanner;
 
 import org.eclipse.cdt.core.index.IIndexFileLocation;
 import org.eclipse.cdt.core.parser.FileContent;
+import org.eclipse.cdt.internal.core.parser.IMacroDictionary;
 import org.eclipse.cdt.internal.core.parser.scanner.InternalFileContent;
 import org.eclipse.cdt.internal.core.parser.scanner.InternalFileContentProvider;
 
 public class FileCodeReaderFactory extends InternalFileContentProvider {
-
     private static FileCodeReaderFactory instance;
 
     private FileCodeReaderFactory() {}
-
     
     @Override
-	public InternalFileContent getContentForInclusion(String path) {
+	public InternalFileContent getContentForInclusion(String path,
+			IMacroDictionary macroDictionary) {
 		return (InternalFileContent) FileContent.createForExternalFileLocation(path);
 	}
 
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/scanner/LocationMapTests.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/scanner/LocationMapTests.java
index 7b8fccea0d1..ed65bacc85c 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/scanner/LocationMapTests.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/scanner/LocationMapTests.java
@@ -6,7 +6,7 @@
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
- *    Markus Schorn - initial API and implementation
+ *     Markus Schorn - initial API and implementation
  *******************************************************************************/ 
 package org.eclipse.cdt.core.parser.tests.scanner;
 
@@ -37,10 +37,10 @@ import org.eclipse.cdt.core.dom.ast.IASTPreprocessorStatement;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorUndefStatement;
 import org.eclipse.cdt.core.dom.ast.IASTProblem;
 import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit;
-import org.eclipse.cdt.core.dom.ast.IBinding;
-import org.eclipse.cdt.core.dom.ast.IMacroBinding;
 import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit.IDependencyTree;
 import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit.IDependencyTree.IASTInclusionNode;
+import org.eclipse.cdt.core.dom.ast.IBinding;
+import org.eclipse.cdt.core.dom.ast.IMacroBinding;
 import org.eclipse.cdt.core.testplugin.CTestPlugin;
 import org.eclipse.cdt.core.testplugin.util.BaseTestCase;
 import org.eclipse.cdt.core.testplugin.util.TestSourceReader;
@@ -49,8 +49,8 @@ import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPASTTranslationUnit;
 import org.eclipse.cdt.internal.core.parser.scanner.CharArray;
 import org.eclipse.cdt.internal.core.parser.scanner.ILocationCtx;
 import org.eclipse.cdt.internal.core.parser.scanner.ImageLocationInfo;
-import org.eclipse.cdt.internal.core.parser.scanner.LocationMap;
 import org.eclipse.cdt.internal.core.parser.scanner.Lexer.LexerOptions;
+import org.eclipse.cdt.internal.core.parser.scanner.LocationMap;
 
 public class LocationMapTests extends BaseTestCase {
 	public class Loc implements IASTFileLocation {
@@ -80,6 +80,9 @@ public class LocationMapTests extends BaseTestCase {
 		public IASTFileLocation asFileLocation() {
 			return this;
 		}
+		public IASTPreprocessorIncludeStatement getContextInclusionStatement() {
+			return null;
+		}
 	}
 
 	private static final String FN = "filename";
@@ -336,8 +339,8 @@ public class LocationMapTests extends BaseTestCase {
 
 	public void testIncludes() {
 		init(DIGITS);
-		fLocationMap.encounterPoundInclude(0, 0, 0, 0, "n1".toCharArray(), null, true, false, false);
-		fLocationMap.encounterPoundInclude(0, 1, 3, 16, "n2".toCharArray(), "f2", false , true, false);
+		fLocationMap.encounterPoundInclude(0, 0, 0, 0, "n1".toCharArray(), null, true, false, false, null);
+		fLocationMap.encounterPoundInclude(0, 1, 3, 16, "n2".toCharArray(), "f2", false , true, false, null);
 		IASTPreprocessorIncludeStatement[] includes= fLocationMap.getIncludeDirectives();
 		assertEquals(2, includes.length);
 		checkInclude(includes[0], "", "", "n1", "", true, false, FN, 0, 0, 1, 0, 0);
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/EmptyIndexFragment.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/EmptyIndexFragment.java
index 30d98de7f11..151109c0c80 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/EmptyIndexFragment.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/EmptyIndexFragment.java
@@ -21,6 +21,7 @@ import org.eclipse.cdt.core.index.IIndexFileLocation;
 import org.eclipse.cdt.core.index.IIndexLinkage;
 import org.eclipse.cdt.core.index.IIndexMacro;
 import org.eclipse.cdt.core.index.IndexFilter;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.internal.core.index.IIndexFragment;
 import org.eclipse.cdt.internal.core.index.IIndexFragmentBinding;
 import org.eclipse.cdt.internal.core.index.IIndexFragmentFile;
@@ -100,13 +101,24 @@ public class EmptyIndexFragment implements IIndexFragment {
 		return 0;
 	}
 
+	@Deprecated
 	public IIndexFragmentFile getFile(int linkageID, IIndexFileLocation location)
 			throws CoreException {
 		return null;
 	}
 
+	public IIndexFragmentFile getFile(int linkageID, IIndexFileLocation location,
+			ISignificantMacros sigMacros) throws CoreException {
+		return null;
+	}
+
+	public IIndexFragmentFile[] getFiles(int linkageID, IIndexFileLocation location)
+			throws CoreException {
+		return IIndexFragmentFile.EMPTY_ARRAY;
+	}
+	
 	public IIndexFragmentFile[] getFiles(IIndexFileLocation location) throws CoreException {
-		return new IIndexFragmentFile[0];
+		return IIndexFragmentFile.EMPTY_ARRAY;
 	}
 
 	public long getLastWriteAccess() {
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexBindingResolutionTestBase.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexBindingResolutionTestBase.java
index 54bf1201d2f..ffe5e705c22 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexBindingResolutionTestBase.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexBindingResolutionTestBase.java
@@ -6,13 +6,16 @@
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
- *    Andrew Ferguson (Symbian) - Initial implementation
- *    IBM Corporation
- *    Markus Schorn (Wind River Systems)
+ *     Andrew Ferguson (Symbian) - Initial implementation
+ *     IBM Corporation
+ *     Markus Schorn (Wind River Systems)
+ *     Sergey Prigogin (Google)
  *******************************************************************************/
 package org.eclipse.cdt.internal.index.tests;
 
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
 
 import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.dom.IPDOMManager;
@@ -81,14 +84,19 @@ public abstract class IndexBindingResolutionTestBase extends BaseTestCase {
 	}
 	
 	protected IASTName findName(String section, int len) {
-		IASTTranslationUnit ast = strategy.getAst();
-		final IASTNodeSelector nodeSelector = ast.getNodeSelector(null);
-		final int offset = strategy.getTestData()[1].indexOf(section);
-		IASTName name= nodeSelector.findName(offset, len);
-		if (name == null)
-			name= nodeSelector.findImplicitName(offset, len);
+		for (int i = 0; i < strategy.getAstCount(); i++) {
+			IASTTranslationUnit ast = strategy.getAst(i);
+			final IASTNodeSelector nodeSelector = ast.getNodeSelector(null);
+			final int offset = strategy.getAstSource(i).indexOf(section);
+			if (offset >= 0) {
+				IASTName name= nodeSelector.findName(offset, len);
+				if (name == null)
+					name= nodeSelector.findImplicitName(offset, len);
+				return name;
+			}
+		}
 		
-		return name;
+		return null;
 	}
 	
 	/**
@@ -210,7 +218,9 @@ public abstract class IndexBindingResolutionTestBase extends BaseTestCase {
 		IIndex getIndex();
 		void setUp() throws Exception;
 		void tearDown() throws Exception;
-		public IASTTranslationUnit getAst();
+		public int getAstCount();
+		public IASTTranslationUnit getAst(int index);
+		public StringBuilder getAstSource(int index);
 		public StringBuilder[] getTestData();
 		public ICProject getCProject();
 		public boolean isCompositeIndex();
@@ -258,13 +268,25 @@ public abstract class IndexBindingResolutionTestBase extends BaseTestCase {
 			return testData;
 		}
 
-		public IASTTranslationUnit getAst() {
+		public int getAstCount() {
+			return 1;
+		}
+
+		public IASTTranslationUnit getAst(int index) {
+			if (index != 0)
+				throw new IllegalArgumentException();
 			return ast;
 		}
 
+		public StringBuilder getAstSource(int index) {
+			if (index != 0)
+				throw new IllegalArgumentException();
+			return testData[1];
+		}
+
 		public void setUp() throws Exception {
-			cproject = cpp ? CProjectHelper.createCCProject(getName()+System.currentTimeMillis(), "bin", IPDOMManager.ID_NO_INDEXER) 
-					: CProjectHelper.createCProject(getName()+System.currentTimeMillis(), "bin", IPDOMManager.ID_NO_INDEXER);
+			cproject = cpp ? CProjectHelper.createCCProject(getName() + System.currentTimeMillis(), "bin", IPDOMManager.ID_NO_INDEXER) 
+					: CProjectHelper.createCProject(getName() + System.currentTimeMillis(), "bin", IPDOMManager.ID_NO_INDEXER);
 			Bundle b = CTestPlugin.getDefault().getBundle();
 			testData = TestSourceReader.getContentsForTest(b, "parser", IndexBindingResolutionTestBase.this.getClass(), getName(), 2);
 
@@ -275,7 +297,7 @@ public abstract class IndexBindingResolutionTestBase extends BaseTestCase {
 			assertTrue(CCorePlugin.getIndexManager().joinIndexer(360000, new NullProgressMonitor()));
 
 			if (DEBUG) {
-				System.out.println("Project PDOM: "+getName());
+				System.out.println("Project PDOM: " + getName());
 				((PDOM)CCoreInternals.getPDOMManager().getPDOM(cproject)).accept(new PDOMPrettyPrinter());
 			}
 
@@ -304,7 +326,6 @@ public abstract class IndexBindingResolutionTestBase extends BaseTestCase {
 		}
 	}
 
-
 	class SinglePDOMTestStrategy implements ITestStrategy {
 		private IIndex index;
 		private ICProject cproject;
@@ -324,10 +345,22 @@ public abstract class IndexBindingResolutionTestBase extends BaseTestCase {
 			return testData;
 		}
 
-		public IASTTranslationUnit getAst() {
+		public int getAstCount() {
+			return 1;
+		}
+
+		public IASTTranslationUnit getAst(int index) {
+			if (index != 0)
+				throw new IllegalArgumentException();
 			return ast;
 		}
 
+		public StringBuilder getAstSource(int index) {
+			if (index != 0)
+				throw new IllegalArgumentException();
+			return testData[1];
+		}
+
 		public void setUp() throws Exception {
 			cproject = cpp ? CProjectHelper.createCCProject(getName()+System.currentTimeMillis(), "bin", IPDOMManager.ID_NO_INDEXER) 
 					: CProjectHelper.createCProject(getName()+System.currentTimeMillis(), "bin", IPDOMManager.ID_NO_INDEXER);
@@ -370,6 +403,108 @@ public abstract class IndexBindingResolutionTestBase extends BaseTestCase {
 		}
 	}
 
+	/**
+	 * This strategy allows tests to create an arbitrary number of header and source files
+	 * and to obtain ASTs of any subset of the created files.
+	 *
+	 * The first line of each comment section preceding the test contains the name of the file
+	 * to put the contents of the section to. To request the AST of a file, put an asterisk after
+	 * the file name.
+	 */
+	class SinglePDOMTestNamedFilesStrategy implements ITestStrategy {
+		private IIndex index;
+		private ICProject cproject;
+		private StringBuilder[] testData;
+		private final List<StringBuilder> astSources;
+		private final List<IASTTranslationUnit> asts;
+		private final boolean cpp;
+
+		public SinglePDOMTestNamedFilesStrategy(boolean cpp) {
+			this.cpp = cpp;
+			astSources = new ArrayList<StringBuilder>();
+			asts = new ArrayList<IASTTranslationUnit>();
+		}
+
+		public ICProject getCProject() {
+			return cproject;
+		}
+
+		public StringBuilder[] getTestData() {
+			return testData;
+		}
+
+		public int getAstCount() {
+			return asts.size();
+		}
+
+		public IASTTranslationUnit getAst(int index) {
+			return asts.get(index);
+		}
+
+		public StringBuilder getAstSource(int index) {
+			return astSources.get(index);
+		}
+
+		public void setUp() throws Exception {
+			cproject = cpp ? CProjectHelper.createCCProject(getName() + System.currentTimeMillis(), "bin", IPDOMManager.ID_NO_INDEXER) 
+					: CProjectHelper.createCProject(getName() + System.currentTimeMillis(), "bin", IPDOMManager.ID_NO_INDEXER);
+			Bundle b = CTestPlugin.getDefault().getBundle();
+			testData = TestSourceReader.getContentsForTest(b, "parser", IndexBindingResolutionTestBase.this.getClass(), getName(), 0);
+
+			List<IFile> astFiles = new ArrayList<IFile>();
+			for (int i = 0; i < testData.length; i++) {
+				StringBuilder contents = testData[i];
+				int endOfLine = contents.indexOf("\n");
+				if (endOfLine >= 0)
+					endOfLine++;
+				else
+					endOfLine = contents.length();
+				String filename = contents.substring(0, endOfLine).trim();
+				contents.delete(0, endOfLine);  // Remove first line from the file contents
+				boolean astRequested = filename.endsWith("*");
+				if (astRequested) {
+					filename = filename.substring(0, filename.length() - 1).trim();
+				}
+				IFile file = TestSourceReader.createFile(cproject.getProject(), new Path(filename), contents.toString());
+				if (astRequested || (i == testData.length - 1 && astFiles.isEmpty())) {
+					astSources.add(contents);
+					astFiles.add(file);
+				}
+			}
+			CCorePlugin.getIndexManager().setIndexerId(cproject, IPDOMManager.ID_FAST_INDEXER);
+			assertTrue(CCorePlugin.getIndexManager().joinIndexer(360000, new NullProgressMonitor()));
+			
+			if (DEBUG) {
+				System.out.println("Project PDOM: "+getName());
+				((PDOM) CCoreInternals.getPDOMManager().getPDOM(cproject)).accept(new PDOMPrettyPrinter());
+			}
+
+			index= CCorePlugin.getIndexManager().getIndex(cproject);
+
+			index.acquireReadLock();
+			for (IFile file : astFiles) {
+				asts.add(TestSourceReader.createIndexBasedAST(index, cproject, file));
+			}
+		}
+
+		public void tearDown() throws Exception {
+			if (index != null) {
+				index.releaseReadLock();
+			}
+			if (cproject != null) {
+				cproject.getProject().delete(IResource.FORCE | IResource.ALWAYS_DELETE_PROJECT_CONTENT, new NullProgressMonitor());
+			}
+		}
+
+		public IIndex getIndex() {
+			return index;
+		}
+		
+		public boolean isCompositeIndex() {
+			return false;
+		}
+	}
+
 	class ReferencedProject implements ITestStrategy {
 		private IIndex index;
 		private ICProject cproject, referenced;
@@ -445,10 +580,22 @@ public abstract class IndexBindingResolutionTestBase extends BaseTestCase {
 			return referenced;
 		}
 
-		public IASTTranslationUnit getAst() {
+		public int getAstCount() {
+			return 1;
+		}
+
+		public IASTTranslationUnit getAst(int index) {
+			if (index != 0)
+				throw new IllegalArgumentException();
 			return ast;
 		}
 
+		public StringBuilder getAstSource(int index) {
+			if (index != 0)
+				throw new IllegalArgumentException();
+			return testData[1];
+		}
+
 		public IIndex getIndex() {
 			return index;
 		}
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexBugsTests.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexBugsTests.java
index fd67979eb33..293cbc8ae73 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexBugsTests.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexBugsTests.java
@@ -289,6 +289,17 @@ public class IndexBugsTests extends BaseTestCase {
     	return TestSourceReader.createFile(container, new Path(fileName), contents);
     }
 
+	private IIndexFile getIndexFile(IFile file) throws CoreException {
+		return getIndexFile(fIndex, file);
+	}			
+
+	private IIndexFile getIndexFile(IIndex index, IFile file) throws CoreException {
+		IIndexFile[] files = index.getFiles(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
+		assertTrue("Can't find " + file.getLocation(), files.length > 0);
+		assertEquals("Found " + files.length + " files for " + file.getLocation() + " instead of one", 1, files.length);
+		return files[0];
+	}			
+
 	private void waitForIndexer() throws InterruptedException {
 		final IIndexManager indexManager = CCorePlugin.getIndexManager();
 		assertTrue(indexManager.joinIndexer(INDEX_WAIT_TIME, npm()));
@@ -459,8 +470,7 @@ public class IndexBugsTests extends BaseTestCase {
 
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(file);
 			IIndexInclude[] includes= ifile.getIncludes();
 			assertEquals(1, includes.length);
 			IIndexInclude i= includes[0];
@@ -484,8 +494,7 @@ public class IndexBugsTests extends BaseTestCase {
 
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(file);
 			IIndexInclude[] includes= ifile.getIncludes();
 			assertEquals(1, includes.length);
 			IIndexInclude i= includes[0];
@@ -561,8 +570,7 @@ public class IndexBugsTests extends BaseTestCase {
 
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(file);
 			IIndexInclude[] includes= ifile.getIncludes();
 			assertEquals(1, includes.length);
 			IIndexInclude i= includes[0];
@@ -585,8 +593,7 @@ public class IndexBugsTests extends BaseTestCase {
 
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(file);
 			IIndexInclude[] includes= ifile.getIncludes();
 			assertEquals(1, includes.length);
 			IIndexInclude i= includes[0];
@@ -612,8 +619,7 @@ public class IndexBugsTests extends BaseTestCase {
 
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(file);
 			IIndexMacro[] macros= ifile.getMacros();
 			assertEquals(3, macros.length);
 			IIndexMacro m= macros[0];
@@ -1116,7 +1122,7 @@ public class IndexBugsTests extends BaseTestCase {
 	// #endif
 
 	// #ifndef _h1
-	// #include "header1.h"
+	// #include "header1.h"   // is inactive, but must be resolved
 	// #endif
 
 	// #include "header1.h"
@@ -1127,7 +1133,7 @@ public class IndexBugsTests extends BaseTestCase {
 
 	// #include "header2.h"
 	// #ifndef _h1
-	// #include "header1.h"
+	// #include "header1.h"   // inactive but resolved.
 	// #endif
 	public void testIncludeGuardsOutsideOfHeader_Bug167100() throws Exception {
 		final IIndexManager indexManager = CCorePlugin.getIndexManager();
@@ -1152,13 +1158,15 @@ public class IndexBugsTests extends BaseTestCase {
 			assertEquals(1, names.length);
 			assertEquals(f4.getFullPath().toString(), names[0].getFile().getLocation().getFullPath());
 
-			IIndexFile idxFile= index.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(f5));
+			IIndexFile[] idxFiles= index.getFiles(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(f5));
+			assertEquals(1, idxFiles.length);
+			IIndexFile idxFile= idxFiles[0];
 			IIndexInclude[] includes= idxFile.getIncludes();
 			assertEquals(2, includes.length);
 			assertTrue(includes[0].isActive());
 			assertTrue(includes[0].isResolved());
 			assertFalse(includes[1].isActive());
-			assertTrue(includes[1].isResolved());
+			// includes[1].isResolved()); May or may not be resolved.
 		} finally {
 			index.releaseReadLock();
 		}
@@ -1658,11 +1666,11 @@ public class IndexBugsTests extends BaseTestCase {
 		waitForIndexer();
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile f= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(f1));
+			IIndexFile f= getIndexFile(f1);
 			IIndexInclude i= f.getIncludes()[0];
 			assertTrue(i.isResolvedByHeuristics());
 
-			f= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(f2));
+			f= getIndexFile(f2);
 			i= f.getIncludes()[0];
 			assertFalse(i.isResolvedByHeuristics());
 		} finally {
@@ -1683,7 +1691,7 @@ public class IndexBugsTests extends BaseTestCase {
 		waitForIndexer();
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile f= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(f1));
+			IIndexFile f= getIndexFile(f1);
 			IIndexInclude[] is= f.getIncludes();
 			assertFalse(is[0].isResolved());
 			assertTrue(is[1].isResolvedByHeuristics());
@@ -1702,12 +1710,12 @@ public class IndexBugsTests extends BaseTestCase {
 	// int aOK;
 	// #endif /* A_H_ */
 
+	// #ifndef B_H_
+	// #define B_H_
 	// #ifndef A_H_
 	// #include "a.h"
 	// #endif
 	//
-	// #ifndef B_H_
-	// #define B_H_
 	// int bOK;
 	// #endif
 
@@ -2125,7 +2133,7 @@ public class IndexBugsTests extends BaseTestCase {
 		IIndex index= indexManager.getIndex(fCProject);
 		index.acquireReadLock();
 		try {
-			IIndexFile file= index.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(f));
+			IIndexFile file= getIndexFile(index, f);
 			// check order of includes
 			IIndexInclude[] incs = file.getIncludes();
 			assertEquals(2, incs.length);
@@ -2157,7 +2165,7 @@ public class IndexBugsTests extends BaseTestCase {
 		IIndex index= indexManager.getIndex(fCProject);
 		index.acquireReadLock();
 		try {
-			IIndexFile file= index.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(f));
+			IIndexFile file= getIndexFile(index, f);
 			int idx= testData.indexOf("f(");
 			IIndexName[] names = file.findNames(idx, idx+1);
 			assertEquals(1, names.length);
@@ -2423,4 +2431,4 @@ public class IndexBugsTests extends BaseTestCase {
 			index.releaseReadLock();
 		}
 	}
-}
\ No newline at end of file
+}
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexIncludeTest.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexIncludeTest.java
index 2fda9e95f00..d48ce0825b2 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexIncludeTest.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexIncludeTest.java
@@ -7,6 +7,7 @@
  *
  * Contributors:
  *     Markus Schorn - initial API and implementation
+ *     Sergey Prigogin (Google)
  *******************************************************************************/ 
 package org.eclipse.cdt.internal.index.tests;
 
@@ -64,6 +65,7 @@ public class IndexIncludeTest extends IndexTestBase {
 					CoreModel.newIncludeEntry(fProject.getPath(), null,
 							fProject.getResource().getLocation()) };
 			fProject.setRawPathEntries(entries, npm());
+			IndexerPreferences.set(fProject.getProject(), IndexerPreferences.KEY_INDEX_UNUSED_HEADERS_WITH_DEFAULT_LANG, "false");
 		}
 		fIndex= CCorePlugin.getIndexManager().getIndex(fProject);
 	}
@@ -114,17 +116,16 @@ public class IndexIncludeTest extends IndexTestBase {
 		
 		ResourcesPlugin.getWorkspace().run(new IWorkspaceRunnable() {
 			public void run(IProgressMonitor monitor) throws CoreException {
-				file.setContents(new ByteArrayInputStream( "int included; int CONTEXT;\n".getBytes()), false, false, npm());
-				file.setLocalTimeStamp(timestamp+1000); 
+				file.setContents(new ByteArrayInputStream("int included; int CONTEXT;\n".getBytes()), false, false, npm());
+				file.setLocalTimeStamp(timestamp + 1000); 
 			}
 		}, npm());
 		assertTrue("Timestamp was not increased", file.getLocalTimeStamp() >= timestamp);
 		TestSourceReader.waitUntilFileIsIndexed(fIndex, file, 4000);
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
-			assertNotNull("Can't find " + file.getLocation(), ifile);
-			assertTrue("timestamp not ok", ifile.getTimestamp() >= timestamp);
+			IIndexFile ifile= getIndexFile(file);
+			assertTrue("Timestamp not ok", ifile.getTimestamp() >= timestamp);
 
 			IIndexBinding[] result= fIndex.findBindings(Pattern.compile("testInclude_cpp"), true, IndexFilter.ALL, npm());
 			assertEquals(1, result.length);
@@ -134,6 +135,13 @@ public class IndexIncludeTest extends IndexTestBase {
 		} finally {
 			fIndex.releaseReadLock();
 		}
+	}
+
+	private IIndexFile getIndexFile(IFile file) throws CoreException {
+		IIndexFile[] files = fIndex.getFiles(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
+		assertTrue("Can't find " + file.getLocation(), files.length > 0);
+		assertEquals("Found " + files.length + " files for " + file.getLocation() + " instead of one", 1, files.length);
+		return files[0];
 	}			
 
 	// {source20061107}
@@ -150,8 +158,7 @@ public class IndexIncludeTest extends IndexTestBase {
 
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(file);
 			IIndexInclude[] includes= ifile.getIncludes();
 			assertEquals(2, includes.length);
 
@@ -174,8 +181,7 @@ public class IndexIncludeTest extends IndexTestBase {
 
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(file);
 			IIndexInclude[] includes= ifile.getIncludes();
 			assertEquals(1, includes.length);
 
@@ -194,8 +200,7 @@ public class IndexIncludeTest extends IndexTestBase {
 
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(file);
 			IIndexInclude[] includes= ifile.getIncludes();
 			assertEquals(1, includes.length);
 
@@ -215,8 +220,7 @@ public class IndexIncludeTest extends IndexTestBase {
 
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(file);
 			IIndexInclude[] includes= ifile.getIncludes();
 			assertEquals(1, includes.length);
 
@@ -238,7 +242,10 @@ public class IndexIncludeTest extends IndexTestBase {
 	public void testUpdateOfIncluded() throws Exception {
 		String content1 = "int CONTEXT_20070404(x);\n";
 		String content2 = "int CONTEXT_20070404(y);\n";
-		String content3 = "#define CONTEXT_20070404(x) ctx_20070404##x\n #include \"included_20070404.h\"\n int source_20070404;\n";
+		String content3 =
+				"#define CONTEXT_20070404(x) ctx_20070404##x\n" +
+				"#include \"included_20070404.h\"\n" +
+				"int source_20070404;\n";
 		TestSourceReader.createFile(fProject.getProject(), "included_20070404.h", content1);
 		TestSourceReader.createFile(fProject.getProject(), "notIncluded_20070404.h", "int notIncluded_20070404\n;");
 		TestSourceReader.createFile(fProject.getProject(), "includer_20070404.cpp", content3);
@@ -332,8 +339,7 @@ public class IndexIncludeTest extends IndexTestBase {
 
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(header));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(header);
 			IIndexInclude[] includes= fIndex.findIncludedBy(ifile);
 			assertEquals(2, includes.length);
 			
@@ -352,8 +358,7 @@ public class IndexIncludeTest extends IndexTestBase {
 		fIndex.acquireReadLock();
 		try {
 			assertEquals(1, fIndex.findBindings("a20070426".toCharArray(), IndexFilter.ALL_DECLARED, npm()).length);
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(header));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(header);
 			IIndexInclude[] includes= fIndex.findIncludedBy(ifile);
 			assertEquals(2, includes.length);
 			assertEquals(s1.getFullPath().toString(), includes[0].getIncludedByLocation().getFullPath());
@@ -370,8 +375,7 @@ public class IndexIncludeTest extends IndexTestBase {
 		fIndex.acquireReadLock();
 		try {
 			assertEquals(1, fIndex.findBindings("b20070426".toCharArray(), IndexFilter.ALL_DECLARED, npm()).length);
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(header));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(header);
 			IIndexInclude[] includes= fIndex.findIncludedBy(ifile);
 			assertEquals(2, includes.length);
 			assertEquals(s1.getFullPath().toString(), includes[0].getIncludedByLocation().getFullPath());
@@ -448,14 +452,188 @@ public class IndexIncludeTest extends IndexTestBase {
 		standardCheckUpdateIncludes(header, s1, "h20070427");
 	}
 
+	// #ifdef A
+	// static const int a = 0;
+	// #endif
+	// #ifdef B
+	// static const int b = 0;
+	// #endif
+	// #ifdef C
+	// static const int c = 0;
+	// #endif
+
+	// #define A
+	// #include "h1.h"
+	// #undef A
+	// #define B
+	// #include "h1.h"
+	// #undef B
+
+	// #define C
+	// #include "h1.h"
+
+	// #include "h2.h"
+	public void testMultiVariantHeaderUpdate() throws Exception {
+		waitForIndexer();
+		TestScannerProvider.sIncludes= new String[] { fProject.getProject().getLocation().toOSString() };
+		StringBuilder[] contents= getContentsForTest(4);
+		final StringBuilder h1Contents = contents[0];
+		final IFile h1= TestSourceReader.createFile(fProject.getProject(), "h1.h", h1Contents.toString());
+		IFile h2= TestSourceReader.createFile(fProject.getProject(), "h2.h", contents[1].toString());
+		IFile s1= TestSourceReader.createFile(fProject.getProject(), "s1.cpp", contents[2].toString());
+		IFile s2= TestSourceReader.createFile(fProject.getProject(), "s2.cpp", contents[3].toString());
+		TestSourceReader.waitUntilFileIsIndexed(fIndex, s1, INDEXER_WAIT_TIME);
+		TestSourceReader.waitUntilFileIsIndexed(fIndex, s2, INDEXER_WAIT_TIME);
+
+		fIndex.acquireReadLock();
+		try {
+			IIndexFile[] indexFiles = fIndex.getFiles(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(h1));
+			assertEquals(3, indexFiles.length);
+		} finally {
+			fIndex.releaseReadLock();
+		}
+
+		final long timestamp= System.currentTimeMillis();
+		while (true) {
+			int pos = h1Contents.indexOf("int");
+			if (pos < 0)
+				break;
+			h1Contents.replace(pos, pos + "int".length(), "float");
+		}
+		ResourcesPlugin.getWorkspace().run(new IWorkspaceRunnable() {
+			public void run(IProgressMonitor monitor) throws CoreException {
+				h1.setContents(new ByteArrayInputStream(h1Contents.toString().getBytes()), false, false, npm());
+				h1.setLocalTimeStamp(timestamp + 1000); 
+			}
+		}, npm());
+		waitForIndexer();
+
+		fIndex.acquireReadLock();
+		try {
+			IIndexFile[] indexFiles = fIndex.getFiles(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(h1));
+			assertEquals(3, indexFiles.length);
+			for (IIndexFile indexFile : indexFiles) {
+				assertTrue("Timestamp not ok", indexFile.getTimestamp() >= timestamp);
+			}
+		} finally {
+			fIndex.releaseReadLock();
+		}
+	}
+
+	// #ifdef A
+	// static const int a = 0;
+	// #endif
+	// #ifdef B
+	// static const int b = 0;
+	// #endif
+	// #ifdef C
+	// static const int c = 0;
+	// #endif
+
+	// #define A
+	// #include "h1.h"
+	// #undef A
+	// #define B
+	// #include "h1.h"
+	// #undef B
+
+	// #define C
+	// #include "h1.h"
+
+	// #include "h2.h"
+
+	// #ifndef H1_H_
+	// #define H1_H_
+	// #ifdef A
+	// static const int a = 0;
+	// #endif
+	// #ifdef B
+	// static const int b = 0;
+	// #endif
+	// #ifdef C
+	// static const int c = 0;
+	// #endif
+	// #endif // H1_H_
+	public void testPragmaOnceChange() throws Exception {
+		waitForIndexer();
+		TestScannerProvider.sIncludes= new String[] { fProject.getProject().getLocation().toOSString() };
+		CharSequence[] contents= getContentsForTest(5);
+		final CharSequence h1Contents = contents[0];
+		final IFile h1= TestSourceReader.createFile(fProject.getProject(), "h1.h", h1Contents.toString());
+		IFile h2= TestSourceReader.createFile(fProject.getProject(), "h2.h", contents[1].toString());
+		IFile s1= TestSourceReader.createFile(fProject.getProject(), "s1.cpp", contents[2].toString());
+		IFile s2= TestSourceReader.createFile(fProject.getProject(), "s2.cpp", contents[3].toString());
+		TestSourceReader.waitUntilFileIsIndexed(fIndex, s1, INDEXER_WAIT_TIME);
+		TestSourceReader.waitUntilFileIsIndexed(fIndex, s2, INDEXER_WAIT_TIME);
+
+		fIndex.acquireReadLock();
+		try {
+			IIndexFile[] indexFiles = fIndex.getFiles(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(h1));
+			assertEquals(3, indexFiles.length);
+			for (IIndexFile indexFile : indexFiles) {
+				assertFalse(indexFile.hasPragmaOnceSemantics());
+				assertEquals(1, fIndex.findIncludedBy(indexFile).length);
+			}
+		} finally {
+			fIndex.releaseReadLock();
+		}
+
+		// Change h1.h so that it has the pragma-once semantics. 
+		final long t1= System.currentTimeMillis();
+		final String changedContents = contents[4].toString();
+		ResourcesPlugin.getWorkspace().run(new IWorkspaceRunnable() {
+			public void run(IProgressMonitor monitor) throws CoreException {
+				h1.setContents(new ByteArrayInputStream(changedContents.getBytes()), false, false, npm());
+				h1.setLocalTimeStamp(t1 + 1000); 
+			}
+		}, npm());
+		waitForIndexer();
+
+		fIndex.acquireReadLock();
+		try {
+			IIndexFile[] indexFiles = fIndex.getFiles(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(h1));
+			assertEquals(1, indexFiles.length);
+			for (IIndexFile indexFile : indexFiles) {
+				assertTrue("Timestamp not ok", indexFile.getTimestamp() >= t1);
+				assertTrue(indexFile.hasPragmaOnceSemantics());
+				// Included twice by h2.h and once by s1.cpp
+				assertEquals(2, fIndex.findIncludedBy(indexFile).length);
+			}
+		} finally {
+			fIndex.releaseReadLock();
+		}
+
+		// Change h1.h back to the original state without the pragma-once semantics. 
+		final long t2= System.currentTimeMillis();
+		ResourcesPlugin.getWorkspace().run(new IWorkspaceRunnable() {
+			public void run(IProgressMonitor monitor) throws CoreException {
+				h1.setContents(new ByteArrayInputStream(h1Contents.toString().getBytes()), false, false, npm());
+				h1.setLocalTimeStamp(t2 + 2000); 
+			}
+		}, npm());
+		waitForIndexer();
+
+		fIndex.acquireReadLock();
+		try {
+			IIndexFile[] indexFiles = fIndex.getFiles(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(h1));
+			assertEquals(3, indexFiles.length);
+			for (IIndexFile indexFile : indexFiles) {
+				assertTrue("Timestamp not ok", indexFile.getTimestamp() >= t2);
+				assertFalse(indexFile.hasPragmaOnceSemantics());
+				assertEquals(1, fIndex.findIncludedBy(indexFile).length);
+			}
+		} finally {
+			fIndex.releaseReadLock();
+		}
+	}
+
 	private void standardCheckUpdateIncludes(IFile header, IFile s1, String tag) throws Exception {
 		fIndex.acquireReadLock();
 		try {
 			assertEquals(1, fIndex.findBindings(tag.toCharArray(), IndexFilter.ALL_DECLARED, npm()).length);
 
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(header));
-			IIndexFile sfile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(s1));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(header);
+			IIndexFile sfile= getIndexFile(s1);
 			IIndexInclude[] includes= fIndex.findIncludedBy(ifile);
 			assertEquals(1, includes.length);
 			assertEquals(s1.getFullPath().toString(), includes[0].getIncludedByLocation().getFullPath());
@@ -464,7 +642,6 @@ public class IndexIncludeTest extends IndexTestBase {
 			assertTrue(includes[0].isResolved());
 			assertFalse(includes[0].isSystemInclude());
 
-			assertNotNull(sfile);
 			includes= fIndex.findIncludes(sfile);
 			assertEquals(3, includes.length);
 			assertEquals(header.getFullPath().toString(), includes[0].getIncludesLocation().getFullPath());
@@ -494,13 +671,11 @@ public class IndexIncludeTest extends IndexTestBase {
 		try {
 			assertEquals(1, fIndex.findBindings(tag.toCharArray(), IndexFilter.ALL_DECLARED, npm()).length);
 
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(header));
-			IIndexFile sfile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(s1));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(header);
+			IIndexFile sfile= getIndexFile(s1);
 			IIndexInclude[] includes= fIndex.findIncludedBy(ifile);
 			assertEquals(0, includes.length);
 
-			assertNotNull(sfile);
 			includes= fIndex.findIncludes(sfile);
 			assertEquals(2, includes.length);
 
@@ -525,9 +700,8 @@ public class IndexIncludeTest extends IndexTestBase {
 		try {
 			assertEquals(1, fIndex.findBindings(tag.toCharArray(), IndexFilter.ALL_DECLARED, npm()).length);
 
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(header));
-			IIndexFile sfile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(s1));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(header);
+			IIndexFile sfile= getIndexFile(s1);
 			IIndexInclude[] includes= fIndex.findIncludedBy(ifile);
 			assertEquals(1, includes.length);
 			assertEquals(s1.getFullPath().toString(), includes[0].getIncludedByLocation().getFullPath());
@@ -536,7 +710,6 @@ public class IndexIncludeTest extends IndexTestBase {
 			assertTrue(includes[0].isResolved());
 			assertTrue(includes[0].isSystemInclude());
 
-			assertNotNull(sfile);
 			includes= fIndex.findIncludes(sfile);
 			assertEquals(2, includes.length);
 			assertEquals(header.getFullPath().toString(), includes[0].getIncludesLocation().getFullPath());
@@ -560,9 +733,8 @@ public class IndexIncludeTest extends IndexTestBase {
 		try {
 			assertEquals(1, fIndex.findBindings(tag.toCharArray(), IndexFilter.ALL_DECLARED, npm()).length);
 
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(header));
-			IIndexFile sfile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(s1));
-			assertNotNull(ifile);
+			IIndexFile ifile= getIndexFile(header);
+			IIndexFile sfile= getIndexFile(s1);
 			IIndexInclude[] includes= fIndex.findIncludedBy(ifile);
 			assertEquals(1, includes.length);
 			assertEquals(s1.getFullPath().toString(), includes[0].getIncludedByLocation().getFullPath());
@@ -571,7 +743,6 @@ public class IndexIncludeTest extends IndexTestBase {
 			assertTrue(includes[0].isResolved());
 			assertFalse(includes[0].isSystemInclude());
 
-			assertNotNull(sfile);
 			includes= fIndex.findIncludes(sfile);
 			assertEquals(2, includes.length);
 			assertEquals(header.getFullPath().toString(), includes[0].getIncludesLocation().getFullPath());
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexListenerTest.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexListenerTest.java
index 8be862dd17c..89fdf310f66 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexListenerTest.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexListenerTest.java
@@ -101,9 +101,11 @@ public class IndexListenerTest extends BaseTestCase {
 		assertTrue(im.joinIndexer(10000, npm()));
 		IIndexChangeListener listener = new IIndexChangeListener() {
 			public void indexChanged(IIndexChangeEvent event) {
-				synchronized (mutex) {
-					projects.add(event.getAffectedProject());
-					mutex.notify();
+				if (!event.getFilesWritten().isEmpty()) {
+					synchronized (mutex) {
+						projects.add(event.getAffectedProject());
+						mutex.notify();
+					}
 				}
 			}
 		};
@@ -119,7 +121,6 @@ public class IndexListenerTest extends BaseTestCase {
 			assertTrue(projects.contains(fProject1));
 			projects.clear();
 
-
 			IFile file1= TestSourceReader.createFile(fProject1.getProject(), "test.cpp", "int b;");
 			IFile file2= TestSourceReader.createFile(fProject2.getProject(), "test.cpp", "int c;");
 			synchronized (mutex) {
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexMultiVariantHeaderTest.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexMultiVariantHeaderTest.java
new file mode 100644
index 00000000000..c798cdebc11
--- /dev/null
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexMultiVariantHeaderTest.java
@@ -0,0 +1,142 @@
+/*******************************************************************************
+ * Copyright (c) 2011 Google, Inc and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *	   Sergey Prigogin (Google) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.internal.index.tests;
+
+import junit.framework.TestSuite;
+
+import org.eclipse.cdt.core.dom.ast.IFunction;
+import org.eclipse.cdt.core.dom.ast.cpp.ICPPFunction;
+import org.eclipse.cdt.core.dom.ast.cpp.ICPPVariable;
+
+/**
+ * Tests for header files included in multiple variants.
+ *
+ * The first line of each comment section preceding a test contains the name of the file
+ * to put the contents of the section to. To request the AST of a file, put an asterisk after
+ * the file name.
+ */
+public class IndexMultiVariantHeaderTest extends IndexBindingResolutionTestBase {
+
+	public IndexMultiVariantHeaderTest() {
+		setStrategy(new SinglePDOMTestNamedFilesStrategy(true));
+	}
+
+	public static TestSuite suite() {
+		return suite(IndexMultiVariantHeaderTest.class);
+	}
+	
+	// test.h
+	//	#ifdef func
+	//	#undef func
+	//	#endif
+	//
+	//	#define func(x) foo ## x
+
+	// test.c *
+	//	#include "test.h"
+	//
+	//	void func(1)() {}
+	//
+	//	#undef func
+	//	#define func(x) bar ## x
+	//
+	//	void func(2)() {}
+	//
+	//	#include "test.h"
+	//	void func(3)() {}
+	public void testExampleFromBug197989_Comment0() throws Exception {
+		IFunction f1 = getBindingFromASTName("func(1)", 7, IFunction.class);
+		assertEquals("foo1", f1.getName());
+		IFunction f2 = getBindingFromASTName("func(2)", 7, IFunction.class);
+		assertEquals("bar2", f2.getName());
+		IFunction f3 = getBindingFromASTName("func(3)", 7, IFunction.class);
+		assertEquals("foo3", f3.getName());
+	}
+
+	// stddef.h
+	//	#if !defined(_STDDEF_H) || defined(__need_NULL)
+	//
+	//	#if !defined(__need_NULL)
+	//	#define _STDDEF_H
+	//	#endif /* !defined(__need_NULL) */
+	//
+	//	#if defined(_STDDEF_H) || defined(__need_NULL)
+	//	#define NULL 0
+	//	#endif /* defined(_STDDEF_H) || defined(__need_NULL)  */
+	//	#undef __need_NULL
+	//
+	//	#if defined(_STDDEF_H)
+	//	typedef unsigned int size_t;
+	//	#endif /* defined(_STDDEF_H) */
+	//
+	//	#endif /* !defined(_STDDEF_H) || defined(__need_NULL) */
+
+	// a.h
+	//  #ifndef A_H_
+	//  #define A_H_
+	//	#include "stddef.h"
+	//	#endif /* A_H_ */
+
+	// a.cpp *
+	//	#define __need_NULL
+	//	#include "stddef.h"
+	//	void f1(char* p) {}
+	//	void test() {
+	//	  f1(NULL);
+	//	}
+
+	// b.cpp
+	//	#include "stddef.h"
+	//	#include "a.h"
+
+	// c.cpp *
+	//	#include "a.h"
+	//	void f2(char* p, size_t t) {}
+	//	void test() {
+	//	  f2(NULL, 1);
+	//	}
+	public void testExampleFromBug197989_Comment73() throws Exception {
+		getBindingFromASTName("f1(NULL)", 2, ICPPFunction.class);
+		getBindingFromASTName("f2(NULL, 1)", 2, ICPPFunction.class);
+	}
+
+	// a.h
+	//	external int X;
+
+	// b.h
+	//	#define X y
+	//	#include "a.h"
+	//	#undef X
+	//	#define X z
+	//	#include "a.h"
+
+	// a.cpp *
+	//	#define X x
+	//	#include "a.h"
+	//  static void test() {
+	//	  x = 0;
+	//	}
+
+	// b.cpp *
+	//	#include "b.h"
+	//  static void test() {
+	//	  y = 0;
+	//	  z = 0;
+	//	}
+	public void _testSignificantMacroDetection() throws Exception {
+		// TODO(sprigogin): For this test to work REPORT_SIGNIFICANT_MACROS flag
+		// should be passed to CPreprocessor.expandMacro method. See
+		// http://bugs.eclipse.org/bugs/show_bug.cgi?id=197989#c92 for details.
+		getBindingFromASTName("x = 0", 1, ICPPVariable.class);
+		getBindingFromASTName("y = 0", 1, ICPPVariable.class);
+		getBindingFromASTName("z = 0", 1, ICPPVariable.class);
+	}
+}
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexNamesTests.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexNamesTests.java
index 123318398e4..69ae8c4a08d 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexNamesTests.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexNamesTests.java
@@ -88,6 +88,13 @@ public class IndexNamesTests extends BaseTestCase {
 		return result;
 	}
 
+	private IIndexFile getIndexFile(int linkageID, IFile file) throws CoreException {
+		IIndexFile[] files = fIndex.getFiles(linkageID, IndexLocationFactory.getWorkspaceIFL(file));
+		assertTrue("Can't find " + file.getLocation(), files.length > 0);
+		assertEquals("Found " + files.length + " files for " + file.getLocation() + " instead of one", 1, files.length);
+		return files[0];
+	}
+
 	protected void waitUntilFileIsIndexed(IFile file, int time) throws Exception {
 		TestSourceReader.waitUntilFileIsIndexed(fIndex, file, time);
 	}
@@ -263,7 +270,7 @@ public class IndexNamesTests extends BaseTestCase {
 
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile ifile= fIndex.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
+			IIndexFile ifile= getIndexFile(ILinkage.CPP_LINKAGE_ID, file);
 			IIndexName[] names= ifile.findNames(0, content.length());
 			int j= 0;
 			for (IIndexName indexName : names) {
@@ -321,7 +328,7 @@ public class IndexNamesTests extends BaseTestCase {
 			CoreException {
 		fIndex.acquireReadLock();
 		try {
-			IIndexFile ifile= fIndex.getFile(linkageID, IndexLocationFactory.getWorkspaceIFL(file));
+			IIndexFile ifile= getIndexFile(linkageID, file);
 			IIndexName[] names= ifile.findNames(0, Integer.MAX_VALUE);
 			int j= 0;
 			for (IIndexName indexName : names) {
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexTests.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexTests.java
index 6b3d23b37fd..97982030531 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexTests.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexTests.java
@@ -30,6 +30,7 @@ public class IndexTests extends TestSuite {
 		suite.addTest(IndexNamesTests.suite());
 		suite.addTest(TeamSharedIndexTest.suite());
 		suite.addTest(IndexProviderManagerTest.suite());
+		suite.addTest(IndexMultiVariantHeaderTest.suite());
 		
 		IndexCPPBindingResolutionBugs.addTests(suite);
 		IndexCPPBindingResolutionTest.addTests(suite);
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/DefDeclTests.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/DefDeclTests.java
index 1a6929db213..da46316999e 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/DefDeclTests.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/DefDeclTests.java
@@ -6,8 +6,8 @@
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
- * QNX - Initial API and implementation
- * Markus Schorn (Wind River Systems)
+ *     QNX - Initial API and implementation
+ *     Markus Schorn (Wind River Systems)
  *******************************************************************************/
 package org.eclipse.cdt.internal.pdom.tests;
 
@@ -183,6 +183,11 @@ public class DefDeclTests extends PDOMTestBase {
 		checkReference(binding, "ref" + testNum, ref);
 	}
 
+	private IIndexFile getSingleFile(IIndexFileLocation ifl) throws CoreException {
+		IIndexFile[] files= pdom.getFiles(ILinkage.C_LINKAGE_ID, ifl);
+		assertEquals(1, files.length);
+		return files[0];
+	}
 	/* ------------------ Tests Started Here ------------------------ */
 	public void testInit() {
 		// will fail if setUp fails, maybe timelimit is too small for warm-up
@@ -237,7 +242,7 @@ public class DefDeclTests extends PDOMTestBase {
 		String elName = "foo" + "08";
 
 		IIndexFileLocation ifl= IndexLocationFactory.getIFL((ITranslationUnit) cproject.findElement(new Path("func.c")));
-		IIndexFile file= pdom.getFile(ILinkage.C_LINKAGE_ID, ifl);
+		IIndexFile file= getSingleFile(ifl);
 		int offset= TestSourceReader.indexOfInFile("foo08();", new Path(ifl.getFullPath()));
 		IIndexName[] names= file.findNames(offset, 5);
 		assertEquals(1, names.length);
@@ -249,7 +254,7 @@ public class DefDeclTests extends PDOMTestBase {
 
 		// check the other file
 		ifl= IndexLocationFactory.getIFL((ITranslationUnit) cproject.findElement(new Path("second.c")));
-		file= pdom.getFile(ILinkage.C_LINKAGE_ID, ifl);
+		file= getSingleFile(ifl);
 		offset= TestSourceReader.indexOfInFile("foo08();", new Path(ifl.getFullPath()));
 		names= file.findNames(offset, 5);
 		assertEquals(1, names.length);
diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/IncludesTests.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/IncludesTests.java
index 5f72bcb7994..be8784315ae 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/IncludesTests.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/IncludesTests.java
@@ -22,6 +22,7 @@ import org.eclipse.cdt.core.index.IndexLocationFactory;
 import org.eclipse.cdt.core.model.ICProject;
 import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IResource;
+import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.Path;
 
 /**
@@ -47,26 +48,30 @@ public class IncludesTests extends PDOMTestBase {
 		index.releaseReadLock();
 	}
 	
+	private IIndexFile getIndexFile(IFile file) throws CoreException {
+		IIndexFile[] files = index.getFiles(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
+		assertTrue("Can't find " + file.getLocation(), files.length > 0);
+		assertEquals("Found " + files.length + " files for " + file.getLocation() + " instead of one", 1, files.length);
+		return files[0];
+	}			
+	
 	public void testIncludedBy() throws Exception {
 		IResource loc = project.getProject().findMember("I2.h");
-		IIndexFile file = index.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL((IFile) loc));
-		assertNotNull(file);
+		IIndexFile file = getIndexFile((IFile) loc);
 		IIndexInclude[] allIncludedBy = index.findIncludedBy(file, -1);
 		assertEquals(9, allIncludedBy.length); // i.e. all of them
 	}
-	
+
 	public void testIncludes() throws Exception {
 		IResource loc = project.getProject().findMember("I1.cpp");
-		IIndexFile file = index.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL((IFile) loc));
-		assertNotNull(file);
+		IIndexFile file = getIndexFile((IFile) loc);
 		IIndexInclude[] allIncludesTo= index.findIncludes(file, -1);
 		assertEquals(2, allIncludesTo.length); // i.e. I1.h, I2.h
 	}
 	
 	public void testIncludeName() throws Exception {
 		IResource loc = project.getProject().findMember("a/b/I6.h");
-		IIndexFile file = index.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL((IFile) loc));
-		assertNotNull(file);
+		IIndexFile file = getIndexFile((IFile) loc);
 		IIndexInclude[] allIncludedBy = index.findIncludedBy(file, -1);
 		assertEquals(2, allIncludedBy.length);
 		for (IIndexInclude include : allIncludedBy) {
diff --git a/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/testplugin/util/BaseTestCase.java b/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/testplugin/util/BaseTestCase.java
index d807643ba55..c9a74d91449 100644
--- a/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/testplugin/util/BaseTestCase.java
+++ b/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/testplugin/util/BaseTestCase.java
@@ -37,6 +37,7 @@ import org.eclipse.cdt.internal.core.CCoreInternals;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPASTNameBase;
 import org.eclipse.cdt.internal.core.pdom.CModelListener;
 import org.eclipse.cdt.internal.core.pdom.PDOMManager;
+import org.eclipse.cdt.internal.core.pdom.indexer.AbstractPDOMIndexer;
 import org.eclipse.core.resources.IResourceStatus;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.ILogListener;
@@ -66,6 +67,7 @@ public class BaseTestCase extends TestCase {
 		CPPASTNameBase.sAllowRecursionBindings= false;
 		CPPASTNameBase.sAllowNameComputation= false;
 		CModelListener.sSuppressUpdateOfLastRecentlyUsed= true;
+		AbstractPDOMIndexer.noFilesUpFront= true;
 	}
 	
 	@Override
@@ -294,4 +296,4 @@ public class BaseTestCase extends TestCase {
 		}
 		assertTrue(indexManager.joinIndexer(10000, npm()));
 	}
-}
\ No newline at end of file
+}
diff --git a/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/testplugin/util/TestSourceReader.java b/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/testplugin/util/TestSourceReader.java
index 6718f076766..5c8ea899085 100644
--- a/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/testplugin/util/TestSourceReader.java
+++ b/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/testplugin/util/TestSourceReader.java
@@ -63,9 +63,10 @@ public class TestSourceReader {
 	 * @param srcRoot the directory inside the bundle containing the packages
 	 * @param clazz the name of the class containing the test
 	 * @param testName the name of the test
-	 * @param sections the number of comment sections preceding the named test to return
+	 * @param sections the number of comment sections preceding the named test to return. Pass zero
+	 *     to get all available sections.
 	 * @return an array of StringBuilder objects for each comment section found preceding the named
-	 * test in the source code. 
+	 *     test in the source code. 
 	 * @throws IOException
 	 */
 	public static StringBuilder[] getContentsForTest(Bundle bundle, String srcRoot, Class clazz,
@@ -100,7 +101,7 @@ public class TestSourceReader {
 	    	} else {
 	    		if (content.length() > 0) {
 	    			contents.add(content);
-	    			if (contents.size() == sections + 1)
+	    			if (sections > 0 && contents.size() == sections + 1)
 	    				contents.remove(0);
 	    			content = new StringBuilder();
 	    		}
@@ -285,12 +286,12 @@ public class TestSourceReader {
 			Assert.assertTrue(CCorePlugin.getIndexManager().joinIndexer(timeLeft, new NullProgressMonitor()));
 			index.acquireReadLock();
 			try {
-				IIndexFile pfile= index.getFile(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
-				if (pfile != null && pfile.getTimestamp() >= file.getLocalTimeStamp()) {
+				IIndexFile[] files= index.getFiles(ILinkage.CPP_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
+				if (files.length > 0 && areAllFilesNotOlderThan(files, file.getLocalTimeStamp())) {
 					return;
 				}
-				pfile= index.getFile(ILinkage.C_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
-				if (pfile != null && pfile.getTimestamp() >= file.getLocalTimeStamp()) {
+				files= index.getFiles(ILinkage.C_LINKAGE_ID, IndexLocationFactory.getWorkspaceIFL(file));
+				if (files.length > 0 && areAllFilesNotOlderThan(files, file.getLocalTimeStamp())) {
 					return;
 				}
 			} finally {
@@ -303,7 +304,16 @@ public class TestSourceReader {
 		Assert.fail("Indexing " + file.getFullPath() + " did not complete in time!");
 	}
 
-    public static IASTTranslationUnit createIndexBasedAST(IIndex index, ICProject project, IFile file) throws CModelException, CoreException {
+	private static boolean areAllFilesNotOlderThan(IIndexFile[] files, long timestamp) throws CoreException {
+		for (IIndexFile file : files) {
+			if (file.getTimestamp() < timestamp) {
+				return false;
+			}
+		}
+		return true;
+	}
+
+	public static IASTTranslationUnit createIndexBasedAST(IIndex index, ICProject project, IFile file) throws CModelException, CoreException {
     	ICElement elem= project.findElement(file.getFullPath());
     	if (elem instanceof ITranslationUnit) {
     		ITranslationUnit tu= (ITranslationUnit) elem;
diff --git a/core/org.eclipse.cdt.core/.options b/core/org.eclipse.cdt.core/.options
index 9f00de4f203..7b086655c64 100644
--- a/core/org.eclipse.cdt.core/.options
+++ b/core/org.eclipse.cdt.core/.options
@@ -12,6 +12,9 @@ org.eclipse.cdt.core/debug/parser/exceptions=false
 # Reports scanner activity
 org.eclipse.cdt.core/debug/scanner=false
 
+# Reports scanner activity
+org.eclipse.cdt.core/debug/scanner/missingIncludeGuards=false
+
 # Reports search activity
 org.eclipse.cdt.core/debug/search=false
 
diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/TranslationUnit.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/TranslationUnit.java
index f57924b0116..908aa8fdcaa 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/TranslationUnit.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/TranslationUnit.java
@@ -12,6 +12,7 @@
  *     Anton Leherbauer (Wind River Systems)
  *     Warren Paul (Nokia) - Bug 218266
  *     James Blackburn (Broadcom Corp.)
+ *     Sergey Prigogin (Google)
  *******************************************************************************/
 package org.eclipse.cdt.internal.core.model;
 
@@ -655,18 +656,26 @@ public class TranslationUnit extends Openable implements ITranslationUnit {
 	}
 
 	public boolean isHeaderUnit() {
-		return CCorePlugin.CONTENT_TYPE_CHEADER.equals(contentTypeId)
-				|| CCorePlugin.CONTENT_TYPE_CXXHEADER.equals(contentTypeId);
+		return isHeaderContentType(contentTypeId);
 	}
 
 	public boolean isSourceUnit() {
-		if (isHeaderUnit())
+		return isSourceContentType(contentTypeId);
+	}
+
+	private static boolean isHeaderContentType(String contentType) {
+		return CCorePlugin.CONTENT_TYPE_CHEADER.equals(contentType)
+				|| CCorePlugin.CONTENT_TYPE_CXXHEADER.equals(contentType);
+	}
+
+	private static boolean isSourceContentType(String contentType) {
+		if (isHeaderContentType(contentType))
 			return false;
 
-		return CCorePlugin.CONTENT_TYPE_CSOURCE.equals(contentTypeId)
-				|| CCorePlugin.CONTENT_TYPE_CXXSOURCE.equals(contentTypeId)
-				|| CCorePlugin.CONTENT_TYPE_ASMSOURCE.equals(contentTypeId)
-				|| LanguageManager.getInstance().isContributedContentType(contentTypeId);
+		return CCorePlugin.CONTENT_TYPE_CSOURCE.equals(contentType)
+				|| CCorePlugin.CONTENT_TYPE_CXXSOURCE.equals(contentType)
+				|| CCorePlugin.CONTENT_TYPE_ASMSOURCE.equals(contentType)
+				|| LanguageManager.getInstance().isContributedContentType(contentType);
 	}
 
 	public boolean isCLanguage() {
@@ -769,7 +778,10 @@ public class TranslationUnit extends Openable implements ITranslationUnit {
 	}
 
 	public IASTTranslationUnit getAST(IIndex index, int style, IProgressMonitor monitor) throws CoreException {
-		ITranslationUnit configureWith = getSourceContextTU(index, style);
+		IIndexFile[] contextToHeader = getContextToHeader(index, style);
+		ITranslationUnit configureWith = getConfigureWith(contextToHeader);
+		if (configureWith == this)
+			contextToHeader= null;
 		
 		IScannerInfo scanInfo= configureWith.getScannerInfo((style & AST_SKIP_IF_NO_BUILD_INFO) == 0);
 		if (scanInfo == null) {
@@ -786,7 +798,7 @@ public class TranslationUnit extends Openable implements ITranslationUnit {
 			return null;
 		}
 
-		IncludeFileContentProvider crf= getIncludeFileContentProvider(style, index, language.getLinkageID());
+		IncludeFileContentProvider crf= getIncludeFileContentProvider(style, index, language.getLinkageID(), contextToHeader);
 		int options= 0;
 		if ((style & AST_SKIP_FUNCTION_BODIES) != 0) {
 			options |= ILanguage.OPTION_SKIP_FUNCTION_BODIES;
@@ -812,7 +824,7 @@ public class TranslationUnit extends Openable implements ITranslationUnit {
 		return ast;
 	}
 
-	private IncludeFileContentProvider getIncludeFileContentProvider(int style, IIndex index, int linkageID) {
+	private IncludeFileContentProvider getIncludeFileContentProvider(int style, IIndex index, int linkageID, IIndexFile[] contextToHeader) {
 		final ICProject cprj= getCProject();
 		final ProjectIndexerInputAdapter pathResolver = new ProjectIndexerInputAdapter(cprj);
 		IncludeFileContentProvider fileContentsProvider;
@@ -825,9 +837,7 @@ public class TranslationUnit extends Openable implements ITranslationUnit {
 		if (index != null && (style & AST_SKIP_INDEXED_HEADERS) != 0) {
 			IndexBasedFileContentProvider ibcf= new IndexBasedFileContentProvider(index, pathResolver, linkageID,
 					fileContentsProvider);
-			if ((style & AST_CONFIGURE_USING_SOURCE_CONTEXT) != 0) {
-				ibcf.setSupportFillGapFromContextToHeader(true);
-			}
+			ibcf.setContextToHeaderGap(contextToHeader);
 			fileContentsProvider= ibcf;
 		}
 		
@@ -839,52 +849,83 @@ public class TranslationUnit extends Openable implements ITranslationUnit {
 		return fileContentsProvider;
 	}
 
-	private static int[] CTX_LINKAGES= {ILinkage.CPP_LINKAGE_ID, ILinkage.C_LINKAGE_ID};
-	public ITranslationUnit getSourceContextTU(IIndex index, int style) {
+	private static final int[] CTX_LINKAGES= { ILinkage.CPP_LINKAGE_ID, ILinkage.C_LINKAGE_ID };
+	public IIndexFile[] getContextToHeader(IIndex index, int style) {
 		if (index != null && (style & AST_CONFIGURE_USING_SOURCE_CONTEXT) != 0) {
 			try {
 				fLanguageOfContext= null;
-				for (int element : CTX_LINKAGES) {
-					IIndexFile context= null;
-					final IIndexFileLocation ifl = IndexLocationFactory.getIFL(this);
-					if (ifl != null) {
-						IIndexFile indexFile= index.getFile(element, ifl);
-						if (indexFile != null) {
-							// bug 199412, when a source-file includes itself the context may recurse.
-							HashSet<IIndexFile> visited= new HashSet<IIndexFile>();
-							visited.add(indexFile);
-							indexFile = getParsedInContext(indexFile);
-							while (indexFile != null && visited.add(indexFile)) {
-								context= indexFile;
-								indexFile= getParsedInContext(indexFile);
-							}
-						}
-						if (context != null) {
-							ITranslationUnit tu= CoreModelUtil.findTranslationUnitForLocation(context.getLocation(), getCProject());
-							if (tu != null && tu.isSourceUnit()) {
-								return tu;
+				final IIndexFileLocation ifl = IndexLocationFactory.getIFL(this);
+				if (ifl != null) {
+					IIndexFile best = null;
+					IIndexFile contextOfBest = null;
+					int bestScore= -1;
+					// Find file variant that has the most content and preferably was parsed in
+					// context of a source file.
+					for (int linkageID : CTX_LINKAGES) {
+						for (IIndexFile indexFile : index.getFiles(linkageID, ifl)) {
+							int score= indexFile.getMacros().length * 2;
+							IIndexFile context= getParsedInContext(indexFile);
+							if (isSourceFile(context))
+								score++;
+							if (score > bestScore) {
+								bestScore= score;
+								best= indexFile;
+								contextOfBest = context;
 							}
 						}
 					}
+					
+					if (best != null && contextOfBest != best) {
+						return new IIndexFile[] { contextOfBest, best };
+					}
 				}
 			} catch (CoreException e) {
 				CCorePlugin.log(e);
 			}
 		}
-		return this;
+		return null;
 	}
 
-	private IIndexFile getParsedInContext(IIndexFile indexFile)
-			throws CoreException {
-		IIndexInclude include= indexFile.getParsedInContext();
-		if (include != null) {
-			return include.getIncludedBy();
+	private IIndexFile getParsedInContext(IIndexFile indexFile) throws CoreException {
+		HashSet<IIndexFile> visited= new HashSet<IIndexFile>();
+		// Bug 199412, may recurse.
+		while (visited.add(indexFile)) {
+			IIndexInclude include= indexFile.getParsedInContext();
+			if (include == null)
+				break;
+			indexFile = include.getIncludedBy();
 		}
-		return null;
+		return indexFile;
+	}
+	
+	/**
+	 * Returns <code>true</code> if the given file was parsed in a context of a source file.
+	 * @throws CoreException 
+	 */
+	private boolean isSourceFile(IIndexFile indexFile) throws CoreException {
+		String path = indexFile.getLocation().getURI().getPath();
+		IContentType cType = CCorePlugin.getContentType(getCProject().getProject(), path);
+		if (cType == null)
+			return false;
+
+		return isSourceContentType(cType.getId());
+	}
+
+	private ITranslationUnit getConfigureWith(IIndexFile[] contextToHeader) throws CoreException {
+		if (contextToHeader != null) { 
+			ITranslationUnit configureWith = CoreModelUtil.findTranslationUnitForLocation(
+					contextToHeader[0].getLocation(), getCProject());
+			if (configureWith != null) 
+				return configureWith;
+		}
+		return this;
 	}
 
 	public IASTCompletionNode getCompletionNode(IIndex index, int style, int offset) throws CoreException {
-		ITranslationUnit configureWith= getSourceContextTU(index, style);
+		IIndexFile[] contextToHeader = getContextToHeader(index, style);
+		ITranslationUnit configureWith = getConfigureWith(contextToHeader);
+		if (configureWith == this)
+			contextToHeader= null;
 		
 		IScannerInfo scanInfo = configureWith.getScannerInfo((style & ITranslationUnit.AST_SKIP_IF_NO_BUILD_INFO) == 0);
 		if (scanInfo == null) {
@@ -896,7 +937,7 @@ public class TranslationUnit extends Openable implements ITranslationUnit {
 		ILanguage language= configureWith.getLanguage();
 		fLanguageOfContext= language;
 		if (language != null) {
-			IncludeFileContentProvider crf= getIncludeFileContentProvider(style, index, language.getLinkageID());
+			IncludeFileContentProvider crf= getIncludeFileContentProvider(style, index, language.getLinkageID(), contextToHeader);
 			IASTCompletionNode result = language.getCompletionNode(fileContent, scanInfo, crf, index,
 					ParserUtil.getParserLogService(), offset);
 			if (result != null) {
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IASTFileLocation.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IASTFileLocation.java
index 7dd1462df02..f3a85ea5187 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IASTFileLocation.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IASTFileLocation.java
@@ -50,4 +50,13 @@ public interface IASTFileLocation extends IASTNodeLocation {
      * @return int representing line number or <code>0</code> if not applicable
      */
     public int getEndingLineNumber();
+
+	/**
+	 * Returns the inclusion statement that included this file, or <code>null</code> for
+	 * a top-level file.
+	 * Also <code>null</code> when the file location does not belong to an AST node, e.g.
+	 * if it is obtained from a name in the index.
+	 * @since 5.4
+	 */
+	public IASTPreprocessorIncludeStatement getContextInclusionStatement();
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IASTPreprocessorIncludeStatement.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IASTPreprocessorIncludeStatement.java
index a1c8698ba66..4cf5ca99645 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IASTPreprocessorIncludeStatement.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IASTPreprocessorIncludeStatement.java
@@ -6,20 +6,22 @@
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
- *    IBM - Initial API and implementation
- *    Markus Schorn (Wind River Systems)
+ *     IBM - Initial API and implementation
+ *     Markus Schorn (Wind River Systems)
  *******************************************************************************/
 package org.eclipse.cdt.core.dom.ast;
 
+import org.eclipse.cdt.core.index.IIndexFile;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
+
+
 /**
  * This interface represent a preprocessor #include statement.
  * 
  * @noextend This interface is not intended to be extended by clients.
  * @noimplement This interface is not intended to be implemented by clients.
  */
-public interface IASTPreprocessorIncludeStatement extends
-		IASTPreprocessorStatement {
-
+public interface IASTPreprocessorIncludeStatement extends IASTPreprocessorStatement, IFileNomination {
 	/**
 	 * <code>INCLUDE_NAME</code> describes the relationship between an include directive and
 	 * it's name.
@@ -64,4 +66,33 @@ public interface IASTPreprocessorIncludeStatement extends
 	 * @since 5.1
 	 */
 	public boolean isResolvedByHeuristics();
+
+	/**
+	 * Returns the list of versions of the target file, each of which is 
+	 * identified by its significant macros, that had been included 
+	 * in this translation-unit prior to this statement.
+	 * @noreference This method is not intended to be referenced by clients.
+	 */
+	public ISignificantMacros[] getLoadedVersions();
+
+	/**
+	 * Returns a hash-code for the contents of the file included, or <code>0</code>
+	 * if the content has not been parsed.
+	 * @since 5.4
+	 */
+	public long getContentsHash();
+
+	/**
+	 * Returns true, if an attempt will be or has been made to create AST for the target
+	 * of this inclusion.
+	 * @since 5.4
+	 */
+	public boolean createsAST();
+	
+	/**
+	 * Returns the file from the index that this include statement has pulled in, or <code>null</code>
+	 * if the include creates AST or is unresolved or skipped.
+	 * @since 5.4
+	 */
+	public IIndexFile getImportedIndexFile(); 
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IASTTranslationUnit.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IASTTranslationUnit.java
index 3f467c197dd..3a7dfea8172 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IASTTranslationUnit.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IASTTranslationUnit.java
@@ -16,6 +16,7 @@ import org.eclipse.cdt.core.dom.IName;
 import org.eclipse.cdt.core.index.IIndex;
 import org.eclipse.cdt.core.index.IIndexFileSet;
 import org.eclipse.cdt.core.model.ITranslationUnit;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.core.parser.ParserLanguage;
 import org.eclipse.core.runtime.IAdaptable;
 
@@ -28,7 +29,7 @@ import org.eclipse.core.runtime.IAdaptable;
  * @noextend This interface is not intended to be extended by clients.
  * @noimplement This interface is not intended to be implemented by clients.
  */
-public interface IASTTranslationUnit extends IASTDeclarationListOwner, IAdaptable {
+public interface IASTTranslationUnit extends IASTDeclarationListOwner, IFileNomination, IAdaptable {
 
 	/**
 	 * <code>OWNED_DECLARATION</code> represents the relationship between an <code>IASTTranslationUnit</code> and
@@ -343,4 +344,16 @@ public interface IASTTranslationUnit extends IASTDeclarationListOwner, IAdaptabl
 	 * @since 5.3
 	 */
 	public ITranslationUnit getOriginatingTranslationUnit();
+	
+	/**
+	 * @since 5.4
+	 * @noreference This method is not intended to be referenced by clients.
+	 */
+	public void setSignificantMacros(ISignificantMacros sigMacros);
+
+	/**
+	 * @since 5.4
+	 * @noreference This method is not intended to be referenced by clients.
+	 */
+	public void setPragmaOnceSemantics(boolean value);
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IFileNomination.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IFileNomination.java
new file mode 100644
index 00000000000..28a91aa36d4
--- /dev/null
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IFileNomination.java
@@ -0,0 +1,40 @@
+/*******************************************************************************
+ * Copyright (c) 2011 Wind River Systems, Inc. and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Markus Schorn - initial API and implementation
+ *******************************************************************************/ 
+
+package org.eclipse.cdt.core.dom.ast;
+
+import org.eclipse.cdt.core.index.IIndexFile;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
+import org.eclipse.core.runtime.CoreException;
+
+/**
+ * Interface for constructs that nominate a file for an AST:
+ * {@link IASTTranslationUnit}, {@link IASTPreprocessorIncludeStatement}, {@link IIndexFile}.
+ * @since 5.4
+ * @noimplement This interface is not intended to be implemented by clients.
+ * @noextend This interface is not intended to be extended by clients.
+ */
+public interface IFileNomination {
+	/**
+	 * Returns macros relevant to parsing of the file included by this include statement and their
+	 * definitions at the point of the include. 
+	 * <p>
+	 * This method should only be called after the included file has been parsed. The method will
+	 * return {@link ISignificantMacros#NONE}</code> if it is called prematurely.
+	 * @throws CoreException 
+	 */
+	public ISignificantMacros getSignificantMacros() throws CoreException;
+	
+	/**
+	 * Returns whether pragma once semantics has been detected when parsing the translation unit.
+	 */
+	public boolean hasPragmaOnceSemantics() throws CoreException;
+}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/index/IIndex.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/index/IIndex.java
index ab4050b27fd..2f868eb12e3 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/index/IIndex.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/index/IIndex.java
@@ -19,6 +19,7 @@ import java.util.regex.Pattern;
 import org.eclipse.cdt.core.dom.IName;
 import org.eclipse.cdt.core.dom.ast.IBinding;
 import org.eclipse.cdt.core.dom.ast.IScope;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IProgressMonitor;
 
@@ -133,16 +134,53 @@ public interface IIndex {
 	public long getLastWriteAccess();
 
 	/**
-	 * Returns the file-object for the given location and linkage or returns
-	 * <code>null</code> if the file was not indexed in this linkage.
+	 * Returns the file object for the given location and linkage or <code>null</code> if the file
+	 * was not indexed in this linkage.
+	 * <p>
+	 * When a header file is stored in the index in multiple variants for different sets of macro
+	 * definitions, this method will return an arbitrary one of these variants.
 	 * @param location an IIndexFileLocation representing the location of the file
 	 * @return the file in the index or <code>null</code>
 	 * @throws CoreException
+	 * @deprecated Use {@link #getFile(int, IIndexFileLocation, ISignificantMacros)} or
+	 *     {@link #getFiles(int, IIndexFileLocation)}.
 	 */
+	@Deprecated
 	public IIndexFile getFile(int linkageID, IIndexFileLocation location) throws CoreException;
 
 	/**
-	 * Returns the file-objects for the given location in any linkage.
+	 * Returns the file for the given location, linkage, and significant macros
+	 * May return <code>null</code>, if no such file exists.
+	 *  
+	 * @param linkageID the id of the linkage in which the file has been parsed.
+	 * @param location the IIndexFileLocation representing the location of the file
+	 * @param macroDictionary The names and definitions of the macros used to disambiguate between
+	 *     variants of the file contents corresponding to different inclusion points.
+	 * @return the file for the location, or <code>null</code> if the file is not present in
+	 *     the index
+	 * @throws CoreException
+	 * @since 5.4
+	 */
+	IIndexFile getFile(int linkageID, IIndexFileLocation location, ISignificantMacros significantMacros)
+			throws CoreException;
+
+	/**
+	 * Returns the file objects for the given location and linkage.
+	 * Multiple files are returned when a header file is stored in the index in multiple variants
+	 * for different sets of macro definitions.
+	 * This method may only return files that are actually managed by this fragment.
+	 * This method returns files without content, also.
+	 *  
+	 * @param linkageID the id of the linkage in which the file has been parsed.
+	 * @param location the IIndexFileLocation representing the location of the file
+	 * @return the files for the location and the linkage.
+	 * @throws CoreException
+	 * @since 5.4
+	 */
+	IIndexFile[] getFiles(int linkageID, IIndexFileLocation location) throws CoreException;
+
+	/**
+	 * Returns the file objects for the given location in any linkage.
 	 * @param location an IIndexFileLocation representing the location of the file
 	 * @return an array of file-objects.
 	 * @throws CoreException
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/index/IIndexFile.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/index/IIndexFile.java
index a1cf9c71ee4..69ade650de2 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/index/IIndexFile.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/index/IIndexFile.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2006, 2010 Wind River Systems, Inc. and others.
+ * Copyright (c) 2006, 2011 Wind River Systems, Inc. and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -8,10 +8,13 @@
  * Contributors:
  *     Markus Schorn - initial API and implementation
  *     Andrew Ferguson (Symbian)
+ *     Sergey Prigogin (Google)
  *******************************************************************************/ 
 package org.eclipse.cdt.core.index;
 
+import org.eclipse.cdt.core.dom.ast.IFileNomination;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPUsingDirective;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.core.runtime.CoreException;
 
 /**
@@ -22,7 +25,7 @@ import org.eclipse.core.runtime.CoreException;
  * 
  * @since 4.0
  */
-public interface IIndexFile {
+public interface IIndexFile extends IFileNomination {
 	IIndexFile[] EMPTY_FILE_ARRAY = {};
 
 	/**
@@ -33,6 +36,13 @@ public interface IIndexFile {
 	IIndexFileLocation getLocation() throws CoreException;
 
 	/**
+	 * Returns the significant macros for this version of the file.
+	 * @throws CoreException 
+	 * @since 5.4
+	 */
+	ISignificantMacros getSignificantMacros() throws CoreException;
+	
+	/**
 	 * Returns all includes found in this file.
 	 * @return an array of all includes found in this file
 	 * @throws CoreException
@@ -69,11 +79,9 @@ public interface IIndexFile {
 	long getContentsHash() throws CoreException;
 
 	/**
-	 * Returns the hash-code of the scanner configuration that was used to parse the file.
-	 * <code>0</code> will be returned in case the hash-code is unknown.
-	 * @return the hash-code of the scanner configuration or <code>0</code>.
-	 * @throws CoreException 
+	 * @deprecated Returns 0. 
 	 */
+	@Deprecated
 	int getScannerConfigurationHashcode() throws CoreException;
 
 	/**
@@ -93,7 +101,14 @@ public interface IIndexFile {
 	 * Returns the include that was used to parse this file, may be <code>null</code>.
 	 */
 	IIndexInclude getParsedInContext() throws CoreException;
-	
+
+	/**
+	 * Returns <code>true</code> if the file is a header with #pragma once statement or an include
+	 * guard, or if it is a source file.
+	 * @since 5.4
+	 */
+	public boolean hasPragmaOnceSemantics() throws CoreException;
+
 	/**
 	 * Returns the id of the linkage this file was parsed in.
 	 * @since 5.0
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/index/IIndexFileSet.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/index/IIndexFileSet.java
index 1fff5b334fa..a30d8b1f34f 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/index/IIndexFileSet.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/index/IIndexFileSet.java
@@ -54,4 +54,10 @@ public interface IIndexFileSet {
 	 * @noreference This method is not intended to be referenced by clients.
 	 */
 	void add(IIndexFile indexFile);
+
+	/**
+	 * Removes a file from this set.
+	 * @noreference This method is not intended to be referenced by clients.
+	 */
+	void remove(IIndexFile indexFile);
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/AbstractParserLogService.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/AbstractParserLogService.java
index f45f33486ed..64650e13a17 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/AbstractParserLogService.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/AbstractParserLogService.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2006, 2008 Wind River Systems, Inc. and others.
+ * Copyright (c) 2006, 2011 Wind River Systems, Inc. and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -10,12 +10,39 @@
  *******************************************************************************/ 
 
 package org.eclipse.cdt.core.parser;
+
+import org.eclipse.cdt.internal.core.dom.parser.ParserLogServiceWrapper;
  
 public abstract class AbstractParserLogService implements IParserLogService {
 
+	/**
+	 * @since 5.4
+	 */
+	public static AbstractParserLogService convert(IParserLogService log) {
+		if (log instanceof AbstractParserLogService)
+			return (AbstractParserLogService) log;
+		return new ParserLogServiceWrapper(log);
+	}
+	
 	public void traceLog(String message) {
 	}
 
+	/**
+	 * @param traceOption an option as defined in the .options file.
+	 * @since 5.4
+	 */
+	public boolean isTracing(String traceOption) {
+		return isTracing();
+	}
+	
+	/**
+	 * @param traceOption an option as defined in the .options file.
+	 * @since 5.4
+	 */
+	public void traceLog(String traceOption, String message) {
+		traceLog(message);
+	}
+
 	public void errorLog(String message) {
 	}
 
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/IProblem.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/IProblem.java
index e521287347a..bd1ffc48c7c 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/IProblem.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/IProblem.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- *  Copyright (c) 2000, 2010 IBM Corporation and others.
+ *  Copyright (c) 2000, 2011 IBM Corporation and others.
  *  All rights reserved. This program and the accompanying materials
  *  are made available under the terms of the Eclipse Public License v1.0
  *  which accompanies this distribution, and is available at
@@ -324,6 +324,12 @@ public interface IProblem
 	public final static int PREPROCESSOR_POUND_WARNING = PREPROCESSOR_RELATED | 0x00E;
 	
 	/**
+	 * Maximum inclusion depth is exceeded  
+	 * @since 5.4
+	 */
+	public final static int PREPROCESSOR_EXCEEDS_MAXIMUM_INCLUSION_DEPTH= PREPROCESSOR_RELATED | 0x00F;
+	
+	/**
 	 * Syntax error, detected by the parser.
 	 */
 	public final static int SYNTAX_ERROR = SYNTAX_RELATED | 0x001;
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/ISignificantMacros.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/ISignificantMacros.java
new file mode 100644
index 00000000000..e4182f46133
--- /dev/null
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/ISignificantMacros.java
@@ -0,0 +1,53 @@
+/*******************************************************************************
+ * Copyright (c) 2011 Wind River Systems, Inc. and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Markus Schorn - initial API and implementation
+ *******************************************************************************/ 
+
+package org.eclipse.cdt.core.parser;
+
+import org.eclipse.cdt.core.parser.util.CharArrayUtils;
+import org.eclipse.cdt.internal.core.parser.scanner.SignificantMacros;
+
+/**
+ * Significant macros describe the conditions under which the preprocessor selects
+ * the same active code branches in a file.
+ * @since 5.4
+ * @noextend This interface is not intended to be extended by clients.
+ * @noimplement This interface is not intended to be implemented by clients.
+ */
+public interface ISignificantMacros {
+	interface IVisitor {
+		/**
+		 * Returns whether to continue the visit.
+		 */
+		boolean visitDefined(char[] macro);
+
+		/**
+		 * Returns whether to continue the visit.
+		 */
+		boolean visitUndefined(char[] macro);
+
+		/**
+		 * Returns whether to continue the visit.
+		 */
+		boolean visitValue(char[] macro, char[] value);
+	}
+
+	ISignificantMacros NONE = new SignificantMacros(CharArrayUtils.EMPTY);
+
+	/**
+	 * Returns whether visitor continued its visit till the end.
+	 */
+	boolean accept(IVisitor visitor);
+
+	/**
+	 * Returns the significant macros encoded as an array of characters.
+	 */
+	char[] encode();
+}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/CharArrayObjectMap.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/CharArrayObjectMap.java
index 35fba211343..3f120cd7fed 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/CharArrayObjectMap.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/util/CharArrayObjectMap.java
@@ -19,8 +19,8 @@ import java.util.List;
 /**
  * @author Doug Schaefer
  */
-public class CharArrayObjectMap extends CharTable {
-    public static final CharArrayObjectMap EMPTY_MAP = new CharArrayObjectMap(0) {
+public class CharArrayObjectMap <T> extends CharTable {
+    public static final CharArrayObjectMap<Object> EMPTY_MAP = new CharArrayObjectMap<Object>(0) {
         @Override
 		public Object clone() { return this; }
         @Override
@@ -30,6 +30,14 @@ public class CharArrayObjectMap extends CharTable {
         	throw new UnsupportedOperationException();
         }
     };
+	/**
+	 * @since 5.4
+	 */
+	@SuppressWarnings("unchecked")
+	public static <T> CharArrayObjectMap<T> emptyMap() {
+		return (CharArrayObjectMap<T>) EMPTY_MAP;
+	}
+
 
 	private Object[] valueTable;
 
@@ -38,40 +46,44 @@ public class CharArrayObjectMap extends CharTable {
 		valueTable = new Object[capacity()];
 	}
 	
-	public Object put(char[] key, int start, int length, Object value) {
+	public T put(char[] key, int start, int length, T value) {
 		int i = addIndex(key, start, length);
-		Object oldvalue = valueTable[i];
+		@SuppressWarnings("unchecked")
+		T oldvalue = (T) valueTable[i];
 		valueTable[i] = value;
 		return oldvalue;
 	}
 
-	final public Object put(char[] key, Object value) {
+	final public T put(char[] key, T value) {
 		return put(key, 0, key.length, value);
 	}
 	
-	final public Object get(char[] key, int start, int length) {
+	@SuppressWarnings("unchecked")
+	final public T get(char[] key, int start, int length) {
 		int i = lookup(key, start, length);
 		if (i >= 0)
-			return valueTable[i];
+			return (T) valueTable[i];
 		return null;
 	}
 	
-	final public Object get(char[] key) {
+	final public T get(char[] key) {
 		return get(key, 0, key.length);
 	}
 	
-	final public Object getAt(int i) {
+	@SuppressWarnings("unchecked")
+	final public T getAt(int i) {
 	    if (i < 0 || i > currEntry)
 	        return null;
-	    return valueTable[i];
+	    return (T) valueTable[i];
 	}
 	
-	final public Object remove(char[] key, int start, int length) {
+	final public T remove(char[] key, int start, int length) {
 		int i = lookup(key, start, length);
 		if (i < 0)
 			return null;
 
-		Object value = valueTable[i];
+		@SuppressWarnings("unchecked")
+		T value = (T) valueTable[i];
 
 	    if (i < currEntry)
 			System.arraycopy(valueTable, i + 1, valueTable, i, currEntry - i);
@@ -85,7 +97,8 @@ public class CharArrayObjectMap extends CharTable {
 	
 	@Override
 	public Object clone() {
-        CharArrayObjectMap newTable = (CharArrayObjectMap) super.clone();
+        @SuppressWarnings("unchecked")
+		CharArrayObjectMap<T> newTable = (CharArrayObjectMap<T>) super.clone();
         newTable.valueTable = new Object[capacity()];
 	    System.arraycopy(valueTable, 0, newTable.valueTable, 0, valueTable.length);
 
@@ -149,4 +162,5 @@ public class CharArrayObjectMap extends CharTable {
 	    System.arraycopy(valueTable, 0, values, 0, values.length);
 	    return values;
 	}
+
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ASTInternal.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ASTInternal.java
index e4cfb2ef56d..866a55bf964 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ASTInternal.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ASTInternal.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2006, 2010 Wind River Systems, Inc. and others.
+ * Copyright (c) 2006, 2011 Wind River Systems, Inc. and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -10,6 +10,7 @@
  *******************************************************************************/ 
 package org.eclipse.cdt.internal.core.dom.parser;
 
+import org.eclipse.cdt.core.dom.ast.IASTFileLocation;
 import org.eclipse.cdt.core.dom.ast.IASTName;
 import org.eclipse.cdt.core.dom.ast.IASTNode;
 import org.eclipse.cdt.core.dom.ast.IBinding;
@@ -71,7 +72,7 @@ public class ASTInternal {
 		}
 	}
 
-	public static String getDeclaredInSourceFileOnly(IBinding binding, boolean requireDefinition, PDOMBinding nonLocal) {
+	public static IASTNode getDeclaredInSourceFileOnly(IBinding binding, boolean requireDefinition, PDOMBinding nonLocal) {
 		IASTNode[] decls;
 		IASTNode def;
 		if (binding instanceof ICPPInternalBinding) {
@@ -88,18 +89,19 @@ public class ASTInternal {
 		if (requireDefinition && def == null) {
 			return null;
 		}
-		String filePath= null;
+		IASTNode result= null;
 		if (def != null) {
-			if ((filePath= isPartOfSource(filePath, def)) == null) {
+			if (!isPartOfSource(def))
 				return null;
-			}
+			result= def;
 		}
 		if (decls != null) {
 			for (final IASTNode node : decls) {
 				if (node != null) {
-					if ((filePath= isPartOfSource(filePath, node)) == null) {
+					if (!isPartOfSource(node))
+						return null;
+					if ((result= resolveConflict(result, node)) == null) 
 						return null;
-					}
 				}
 			}
 		}
@@ -110,23 +112,29 @@ public class ASTInternal {
 			} catch (CoreException e) {
 			}
 		}
-		return filePath;
+		return result;
 	}
 
-	private static String isPartOfSource(String filePath, IASTNode decl) {
-		if (decl instanceof ASTNode) {
-			if (((ASTNode) decl).isPartOfSourceFile()) {
-				if (filePath == null)
-					return decl.getContainingFilename();
-				
-				if (filePath.equals(decl.getContainingFilename()))
-					return filePath;
-			}
-		}
-		return null;
+	private static boolean isPartOfSource(IASTNode decl) {
+		return decl instanceof ASTNode && ((ASTNode) decl).isPartOfSourceFile();
+	}
+
+	private static IASTNode resolveConflict(IASTNode n1, IASTNode n2) {
+		if (n1 == null)
+			return n2;
+		
+		IASTFileLocation loc1= n1.getFileLocation();
+		if (loc1 == null)
+			return n2;
+		
+		IASTFileLocation loc2= n2.getFileLocation();
+		if (loc2 != null && loc1.getContextInclusionStatement() != loc2.getContextInclusionStatement()) 
+			return null;
+
+		return n1;
 	}
 
-	public static String getDeclaredInOneFileOnly(IBinding binding) {
+	public static IASTNode getDeclaredInOneFileOnly(IBinding binding) {
 		IASTNode[] decls;
 		IASTNode def;
 		if (binding instanceof ICPPInternalBinding) {
@@ -140,23 +148,19 @@ public class ASTInternal {
 		} else {
 			return null;
 		}
-		String filePath= null;
+		IASTNode result= null;
 		if (def != null) {
-			filePath= def.getContainingFilename();
+			result= def;
 		}
 		if (decls != null) {
 			for (final IASTNode node : decls) {
 				if (node != null) {
-					final String fn = node.getContainingFilename();
-					if (filePath == null) {
-						filePath= fn;
-					} else if (!filePath.equals(fn)) {
+					if ((result= resolveConflict(result, node)) == null) 
 						return null;
-					}
 				}
 			}
 		}
-		return filePath;
+		return result;
 	}
 
 	public static void addDeclaration(IBinding b, IASTNode declaration) {
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ASTTranslationUnit.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ASTTranslationUnit.java
index 63d2265bc31..f6f48df2dda 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ASTTranslationUnit.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/ASTTranslationUnit.java
@@ -37,6 +37,7 @@ import org.eclipse.cdt.core.index.IIndex;
 import org.eclipse.cdt.core.index.IIndexFile;
 import org.eclipse.cdt.core.index.IIndexFileSet;
 import org.eclipse.cdt.core.model.ITranslationUnit;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.core.parser.util.ArrayUtil;
 import org.eclipse.cdt.internal.core.index.IndexBasedFileContentProvider;
 import org.eclipse.cdt.internal.core.parser.scanner.ILocationResolver;
@@ -71,6 +72,9 @@ public abstract class ASTTranslationUnit extends ASTNode implements IASTTranslat
 	private INodeFactory fNodeFactory;
 	private boolean fForContentAssist;
 	private ITranslationUnit fOriginatingTranslationUnit;
+	private ISignificantMacros fSignificantMacros= ISignificantMacros.NONE;
+	private boolean fPragmaOnceSemantics;
+	
 	/** The semaphore controlling exclusive access to the AST. */
 	private final Semaphore fSemaphore= new Semaphore(1);
 
@@ -367,6 +371,7 @@ public abstract class ASTTranslationUnit extends ASTNode implements IASTTranslat
 		if (fIndexFileSet != null) {
 			List<IIndexFile> files= fileContent.getFilesIncluded();
 			for (IIndexFile indexFile : files) {
+				fASTFileSet.remove(indexFile);
 				fIndexFileSet.add(indexFile);
 			}
 		}
@@ -376,13 +381,14 @@ public abstract class ASTTranslationUnit extends ASTNode implements IASTTranslat
 		return fIndexFileSet;
 	}
 	
-	public void replacingFile(InternalFileContentProvider provider, InternalFileContent fc) {
+	public void parsingFile(InternalFileContentProvider provider, InternalFileContent fc) {
 		if (fASTFileSet != null) {
 			if (provider instanceof IndexBasedFileContentProvider) {
 				try {
-					IIndexFile file= ((IndexBasedFileContentProvider) provider).findIndexFile(fc);
-					if (file != null) {
-						fASTFileSet.add(file);
+					for (IIndexFile file : ((IndexBasedFileContentProvider) provider).findIndexFiles(fc)) {
+						if (!fIndexFileSet.contains(file)) {
+							fASTFileSet.add(file);
+						}
 					}
 				} catch (CoreException e) {
 					// Ignore, tracking of replaced files fails.
@@ -450,6 +456,25 @@ public abstract class ASTTranslationUnit extends ASTNode implements IASTTranslat
 		this.fOriginatingTranslationUnit = tu;
 	}
 
+	public ISignificantMacros getSignificantMacros() {
+		return fSignificantMacros;
+	}
+
+	public void setSignificantMacros(ISignificantMacros sigMacros) {
+		assertNotFrozen();
+		if (sigMacros != null)
+			fSignificantMacros= sigMacros;
+	}
+	
+	public boolean hasPragmaOnceSemantics() {
+		return fPragmaOnceSemantics;
+	}
+	
+	public void setPragmaOnceSemantics(boolean value) {
+		assertNotFrozen();
+		fPragmaOnceSemantics= value;
+	}
+
 	/**
 	 * Starts exclusive access 
 	 * @throws InterruptedException
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/AbstractGNUSourceCodeParser.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/AbstractGNUSourceCodeParser.java
index 8baba365940..54e46eacea2 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/AbstractGNUSourceCodeParser.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/AbstractGNUSourceCodeParser.java
@@ -200,7 +200,6 @@ public abstract class AbstractGNUSourceCodeParser implements ISourceCodeParser {
     
     private final INodeFactory nodeFactory;
 	private boolean fActiveCode= true;
-	private int fEndOffset= -1;
 	
     protected AbstractGNUSourceCodeParser(IScanner scanner,
             IParserLogService logService, ParserMode parserMode,
@@ -435,7 +434,6 @@ public abstract class AbstractGNUSourceCodeParser implements ISourceCodeParser {
     	try {
     		return LA(i);
     	} catch (EndOfFileException e) {
-    		fEndOffset= e.getEndOffset();
     		return null;
     	}
     }
@@ -456,7 +454,6 @@ public abstract class AbstractGNUSourceCodeParser implements ISourceCodeParser {
     	try {
     		return LT(i);
     	} catch (EndOfFileException e) {
-    		fEndOffset= e.getEndOffset();
     		return 0;
     	}
     }
@@ -1281,9 +1278,6 @@ public abstract class AbstractGNUSourceCodeParser implements ISourceCodeParser {
 	protected void parseTranslationUnit() {
 		final IASTTranslationUnit tu= getTranslationUnit();
 		declarationList(tu, DeclarationOptions.GLOBAL, false, 0);
-		// Bug 3033152: getEndOffset() is computed off the last node and ignores trailing macros.
-		final int length= Math.max(getEndOffset(), fEndOffset);
-        ((ASTNode) tu).setLength(length);
 	}
 
 	protected final void declarationListInBraces(final IASTDeclarationListOwner tu, int offset, DeclarationOptions options) throws EndOfFileException, BacktrackException {
@@ -1356,7 +1350,6 @@ public abstract class AbstractGNUSourceCodeParser implements ISourceCodeParser {
 				IASTDeclaration declaration= skipProblemDeclaration(offset);
 				addDeclaration(tu, declaration, active);
 				if (!e.endsInactiveCode()) {
-					fEndOffset= e.getEndOffset();
 					break;
 				}
 			} finally {
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/TemplateArgumentDeduction.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/TemplateArgumentDeduction.java
index 03346097b98..d80a85d3c36 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/TemplateArgumentDeduction.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/TemplateArgumentDeduction.java
@@ -227,7 +227,7 @@ public class TemplateArgumentDeduction {
 					ICPPTemplateInstance pInst = (ICPPTemplateInstance) pcheck;
 					ICPPClassTemplate pTemplate= getPrimaryTemplate(pInst);
 					if (pTemplate != null) {
-						ICPPClassType aInst= findBaseInstance((ICPPClassType) argcheck, pTemplate, CPPSemantics.MAX_INHERITANCE_DEPTH);	
+						ICPPClassType aInst= findBaseInstance((ICPPClassType) argcheck, pTemplate);	
 						if (aInst != null && aInst != argcheck) {
 							par= pcheck;
 							arg= aInst;
@@ -467,10 +467,15 @@ public class TemplateArgumentDeduction {
 		return result.toArray(new ICPPTemplateArgument[result.size()]);
 	}
 
+	
 	/**
 	 * 14.8.2.1.3 If P is a class and has the form template-id, then A can be a derived class of the deduced A.
 	 */
-	private static ICPPClassType findBaseInstance(ICPPClassType a, ICPPClassTemplate pTemplate, int maxdepth) throws DOMException {
+	private static ICPPClassType findBaseInstance(ICPPClassType a, ICPPClassTemplate pTemplate) throws DOMException {
+		return findBaseInstance(a, pTemplate, CPPSemantics.MAX_INHERITANCE_DEPTH, new HashSet<Object>());
+	}
+
+	private static ICPPClassType findBaseInstance(ICPPClassType a, ICPPClassTemplate pTemplate, int maxdepth, HashSet<Object> handled) throws DOMException {
 		if (a instanceof ICPPTemplateInstance) {
 			final ICPPTemplateInstance inst = (ICPPTemplateInstance) a;
 			ICPPClassTemplate tmpl= getPrimaryTemplate(inst);
@@ -480,8 +485,8 @@ public class TemplateArgumentDeduction {
 		if (maxdepth-- > 0) {
 			for (ICPPBase cppBase : a.getBases()) {
 				IBinding base= cppBase.getBaseClass();
-				if (base instanceof ICPPClassType) {
-					final ICPPClassType inst= findBaseInstance((ICPPClassType) base, pTemplate, maxdepth);
+				if (base instanceof ICPPClassType && handled.add(base)) {
+					final ICPPClassType inst= findBaseInstance((ICPPClassType) base, pTemplate, maxdepth, handled);
 					if (inst != null)
 						return inst;
 				}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/CIndex.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/CIndex.java
index c5907a0da4e..fa011fc2c37 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/CIndex.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/CIndex.java
@@ -17,13 +17,13 @@ package org.eclipse.cdt.internal.core.index;
 
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.BitSet;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Set;
 import java.util.regex.Pattern;
 
 import org.eclipse.cdt.core.CCorePlugin;
@@ -42,6 +42,7 @@ import org.eclipse.cdt.core.index.IIndexInclude;
 import org.eclipse.cdt.core.index.IIndexMacro;
 import org.eclipse.cdt.core.index.IIndexName;
 import org.eclipse.cdt.core.index.IndexFilter;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.internal.core.dom.Linkage;
 import org.eclipse.cdt.internal.core.index.composite.CompositingNotImplementedError;
 import org.eclipse.cdt.internal.core.index.composite.ICompositesFactory;
@@ -208,6 +209,7 @@ public class CIndex implements IIndex {
 		return findNames(binding, FIND_REFERENCES);
 	}
 
+	@Deprecated
 	public IIndexFile getFile(int linkageID, IIndexFileLocation location) throws CoreException {
 		for (int i = 0; i < fPrimaryFragmentCount; i++) {
 			IIndexFragmentFile candidate= fFragments[i].getFile(linkageID, location);
@@ -218,19 +220,53 @@ public class CIndex implements IIndex {
 		return null;
 	}
 
+	public IIndexFile getFile(int linkageID, IIndexFileLocation location,
+			ISignificantMacros significantMacros) throws CoreException {
+		for (int i = 0; i < fPrimaryFragmentCount; i++) {
+			IIndexFragmentFile candidate= fFragments[i].getFile(linkageID, location, significantMacros);
+			if (candidate != null && candidate.hasContent()) {
+				return candidate;
+			}
+		}
+		return null;
+	}
+
+	public IIndexFile[] getFiles(int linkageID, IIndexFileLocation location) throws CoreException {
+		if (location == null) {
+			return IIndexFile.EMPTY_FILE_ARRAY;
+		}
+		Set<ISignificantMacros> handled = new HashSet<ISignificantMacros>();
+		ArrayList<IIndexFragmentFile> result= new ArrayList<IIndexFragmentFile>();
+		for (int i = 0; i < fPrimaryFragmentCount; i++) {
+			IIndexFragmentFile[] candidates= fFragments[i].getFiles(linkageID, location);
+			for (IIndexFragmentFile candidate : candidates) {
+				if (candidate.hasContent()) {
+					ISignificantMacros macroKey = candidate.getSignificantMacros();
+					if (handled.add(macroKey)) {
+						result.add(candidate);
+					}
+				}
+			}
+		}
+		if (result.isEmpty()) {
+			return IIndexFile.EMPTY_FILE_ARRAY;
+		}
+		return result.toArray(new IIndexFile[result.size()]);
+	}
+
 	public IIndexFile[] getFiles(IIndexFileLocation location) throws CoreException {
 		if (location == null) {
 			return IIndexFile.EMPTY_FILE_ARRAY;
 		}
+		Set<FileContentKey> keys = new HashSet<FileContentKey>();
 		ArrayList<IIndexFragmentFile> result= new ArrayList<IIndexFragmentFile>();
-		BitSet linkages= new BitSet();
 		for (int i = 0; i < fPrimaryFragmentCount; i++) {
 			IIndexFragmentFile[] candidates= fFragments[i].getFiles(location);
 			for (IIndexFragmentFile candidate : candidates) {
-				int linkage= candidate.getLinkageID();
-				if (!linkages.get(linkage) && candidate.hasContent()) {
-					result.add(candidate);
-					linkages.set(linkage);
+				if (candidate.hasContent()) {
+					if (keys.add(new FileContentKey(candidate.getLinkageID(), candidate.getLocation(), candidate.getSignificantMacros()))) {
+						result.add(candidate);
+					}
 				}
 			}
 		}
@@ -241,16 +277,16 @@ public class CIndex implements IIndex {
 	}
 
 	public IIndexFile resolveInclude(IIndexInclude include) throws CoreException {
-		if (!include.isResolved()) {
-			return null;
-		}
 		IIndexFragmentInclude fragmentInclude = (IIndexFragmentInclude) include;
 		IIndexFragmentFile result= fragmentInclude.getIncludes();
-		if (result != null && result.hasContent()) {
+		if (result == null)
+			return null;
+		
+		if (result.hasContent()) {
 			return result;
 		}
 
-		return getFile(include.getIncludedBy().getLinkageID(), include.getIncludesLocation());
+		return getFile(result.getLinkageID(), result.getLocation(), result.getSignificantMacros());
 	}
 
 	public IIndexInclude[] findIncludedBy(IIndexFile file) throws CoreException {
@@ -259,22 +295,25 @@ public class CIndex implements IIndex {
 
 	public IIndexInclude[] findIncludedBy(IIndexFile file, int depth) throws CoreException {
 		List<IIndexInclude> result= new ArrayList<IIndexInclude>();
-		findIncludedBy(Collections.singletonList(file), result, depth, new HashSet<IIndexFileLocation>());
+		findIncludedBy(file.getLinkageID(), Collections.singletonList(file), result, depth,
+				new HashSet<FileContentKey>());
 		return result.toArray(new IIndexInclude[result.size()]);
 	}
 
-	public void findIncludedBy(List<IIndexFile> in, List<IIndexInclude> out, int depth,
-			HashSet<IIndexFileLocation> handled) throws CoreException {
+	public void findIncludedBy(int linkageID, List<IIndexFile> in, List<IIndexInclude> out, int depth,
+			HashSet<FileContentKey> handled) throws CoreException {
 		List<IIndexFile> nextLevel= depth != 0 ? new LinkedList<IIndexFile>() : null;
 		for (IIndexFile iIndexFile : in) {
 			IIndexFragmentFile file = (IIndexFragmentFile) iIndexFile;
 			for (int j = 0; j < fPrimaryFragmentCount; j++) {
 				IIndexInclude[] includedBy= fFragments[j].findIncludedBy(file);
 				for (IIndexInclude include : includedBy) {
-					if (handled.add(include.getIncludedByLocation())) {
+					final IIndexFile includer = include.getIncludedBy();
+					FileContentKey key= new FileContentKey(linkageID, includer.getLocation(), includer.getSignificantMacros());
+					if (handled.add(key)) {
 						out.add(include);
 						if (nextLevel != null) {
-							nextLevel.add(include.getIncludedBy());
+							nextLevel.add(includer);
 						}
 					}
 				}
@@ -286,10 +325,9 @@ public class CIndex implements IIndex {
 		if (depth > 0) {
 			depth--;
 		}
-		findIncludedBy(nextLevel, out, depth, handled);
+		findIncludedBy(linkageID, nextLevel, out, depth, handled);
 	}
 
-
 	public IIndexInclude[] findIncludes(IIndexFile file) throws CoreException {
 		return findIncludes(file, 0);
 	}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/EmptyCIndex.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/EmptyCIndex.java
index eb522b54d30..acc91a98edc 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/EmptyCIndex.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/EmptyCIndex.java
@@ -29,6 +29,7 @@ import org.eclipse.cdt.core.index.IIndexInclude;
 import org.eclipse.cdt.core.index.IIndexMacro;
 import org.eclipse.cdt.core.index.IIndexName;
 import org.eclipse.cdt.core.index.IndexFilter;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IProgressMonitor;
 
@@ -54,10 +55,20 @@ final public class EmptyCIndex implements IIndex {
 		return IIndexFragmentName.EMPTY_NAME_ARRAY;
 	}
 
+	@Deprecated
 	public IIndexFile getFile(int linkageID, IIndexFileLocation location) {
 		return null;
 	}
 
+	public IIndexFile getFile(int linkageID, IIndexFileLocation location,
+			ISignificantMacros significantFiles) throws CoreException {
+		return null;
+	}
+
+	public IIndexFile[] getFiles(int linkageID, IIndexFileLocation location) throws CoreException {
+		return IIndexFile.EMPTY_FILE_ARRAY;
+	}
+
 	public IIndexFile[] getFiles(IIndexFileLocation location) {
 		return IIndexFile.EMPTY_FILE_ARRAY;
 	}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/FileContentKey.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/FileContentKey.java
new file mode 100644
index 00000000000..2c6b9d327e9
--- /dev/null
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/FileContentKey.java
@@ -0,0 +1,77 @@
+/*******************************************************************************
+ * Copyright (c) 2011 Google, Inc and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ * 	   Sergey Prigogin (Google) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.internal.core.index;
+
+import org.eclipse.cdt.core.index.IIndexFileLocation;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
+
+/**
+ * A key that uniquely determines the preprocessed contents of a file. 
+ */
+public class FileContentKey {
+	private final int linkageID;
+	private final IIndexFileLocation location;
+	private final ISignificantMacros significantMacros;
+
+	/**
+	 * Creates a file content key.
+	 * @param location the file location.
+	 */
+	public FileContentKey(int linkageID, IIndexFileLocation location, ISignificantMacros sigMacros) {
+		this.linkageID= linkageID;
+		this.location = location;
+		this.significantMacros = sigMacros;
+	}
+
+	public int getLinkageID() {
+		return linkageID;
+	}
+
+	public IIndexFileLocation getLocation() {
+		return location;
+	}
+
+	public ISignificantMacros getSignificantMacros() {
+		return significantMacros;
+	}
+
+	@Override
+	public int hashCode() {
+		return (linkageID + location.hashCode() * 31) * 31 + significantMacros.hashCode();
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		FileContentKey other = (FileContentKey) obj;
+		if (linkageID != other.linkageID)
+			return false;
+		
+		if (!location.equals(other.location)) 
+			return false;
+		
+		if (!significantMacros.equals(other.significantMacros)) 
+			return false;
+	
+        return true;
+	}
+	
+	@SuppressWarnings("nls")
+	@Override
+	public String toString() {
+		return linkageID + ": " + location.getURI().toString() + "[" + significantMacros.hashCode() + "]";
+	}
+}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragment.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragment.java
index 42895d8d79b..3675ce5ed57 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragment.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragment.java
@@ -23,6 +23,7 @@ import org.eclipse.cdt.core.index.IIndexFileLocation;
 import org.eclipse.cdt.core.index.IIndexLinkage;
 import org.eclipse.cdt.core.index.IIndexMacro;
 import org.eclipse.cdt.core.index.IndexFilter;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IProgressMonitor;
 
@@ -92,15 +93,56 @@ public interface IIndexFragment {
 	 * May return <code>null</code>, if no such file exists.
 	 * This method may only return files that are actually managed by this fragment.
 	 * This method returns files without content, also.
+	 * <p>
+	 * When a header file is stored in the index in multiple variants for different sets of macro
+	 * definitions, this method will return an arbitrary one of these variants.
+	 *  
 	 * @param linkageID the id of the linkage in which the file has been parsed.
 	 * @param location the IIndexFileLocation representing the location of the file
 	 * @return the file for the location, or <code>null</code> if the file is not present in
 	 *     the index
 	 * @throws CoreException
+	 * @deprecated Use {@link #getFile(int, IIndexFileLocation, ISignificantMacros)} or
+	 *     {@link #getFiles(int, IIndexFileLocation)}.
 	 */
+	@Deprecated
 	IIndexFragmentFile getFile(int linkageID, IIndexFileLocation location) throws CoreException;
 
 	/**
+	 * Returns the file for the given location, linkage, and a set of macro definitions.
+	 * May return <code>null</code>, if no such file exists.
+	 * This method may only return files that are actually managed by this fragment.
+	 * This method returns files without content, also.
+	 *  
+	 * @param linkageID the id of the linkage in which the file has been parsed.
+	 * @param location the IIndexFileLocation representing the location of the file
+	 * @param macroDictionary The names and definitions of the macros used to disambiguate between
+	 *     variants of the file contents corresponding to different inclusion points.
+	 * @return the file for the location, or <code>null</code> if the file is not present in
+	 *     the index
+	 * @throws CoreException
+	 */
+	IIndexFragmentFile getFile(int linkageID, IIndexFileLocation location,
+			ISignificantMacros significantMacros) throws CoreException;
+
+	/**
+	 * Returns the files for the given location and linkage.
+	 * Multiple files are returned when a header file is stored in the index in multiple variants
+	 * for different sets of macro definitions.
+	 * This method may only return files that are actually managed by this fragment.
+	 * This method returns files without content, also.
+	 * <p>
+	 * When a header file is stored in the index in multiple variants for different sets of macro
+	 * definitions, this method will return an arbitrary one of these variants.
+	 *  
+	 * @param linkageID the id of the linkage in which the file has been parsed.
+	 * @param location the IIndexFileLocation representing the location of the file
+	 * @return the files for the location and the linkage.
+	 * @throws CoreException
+	 */
+	IIndexFragmentFile[] getFiles(int linkageID, IIndexFileLocation location) throws CoreException;
+
+	/**
 	 * Returns the files in all linkages for the given location.
 	 * This method may only return files that are actually managed by this fragment.
 	 * @param location the IIndexFileLocation representing the location of the file
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragmentFile.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragmentFile.java
index 887133feb52..210261583b7 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragmentFile.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragmentFile.java
@@ -1,15 +1,15 @@
 /*******************************************************************************
- * Copyright (c) 2006, 2010 Wind River Systems, Inc. and others.
+ * Copyright (c) 2006, 2011 Wind River Systems, Inc. and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
- *    Markus Schorn - initial API and implementation
- *    Andrew Ferguson (Symbian)
+ *     Markus Schorn - initial API and implementation
+ *     Andrew Ferguson (Symbian)
+ *     Sergey Prigogin (Google)
  *******************************************************************************/ 
-
 package org.eclipse.cdt.internal.core.index;
 
 import org.eclipse.cdt.core.index.IIndexFile;
@@ -34,17 +34,16 @@ public interface IIndexFragmentFile extends IIndexFile {
 	void setContentsHash(long hash) throws CoreException;
 
 	/**
-	 * Sets the hash-code of the scanner configuration.
+	 * Sets the hash-code of the file encoding.
 	 * @param hashcode a hash-code or <code>0</code> if it is unknown.
-	 * @throws CoreException 
 	 */
-	void setScannerConfigurationHashcode(int hashcode) throws CoreException;
+	void setEncodingHashcode(int hashcode) throws CoreException;
 
 	/**
-	 * Sets the hash-code of the file encoding.
-	 * @param hashcode a hash-code or <code>0</code> if it is unknown.
+	 * Sets the flag that determines whether the file is a header with #pragma once statement
+	 * or an include guard, or it is a source file and parsed only once because of that.
 	 */
-	void setEncodingHashcode(int hashcode) throws CoreException;
+	void setPragmaOnceSemantics(boolean value) throws CoreException;
 
 	/**
 	 * Returns whether this file contains content in its
@@ -56,4 +55,16 @@ public interface IIndexFragmentFile extends IIndexFile {
 	 * Returns the id of the linkage this file belongs to.
 	 */
 	int getLinkageID() throws CoreException;
+
+	/**
+	 * Changes the inclusions pointing to 'source' to point to this file, instead. 
+	 * The file 'source' must belong to the same fragment as this file.
+	 */
+	void transferIncluders(IIndexFragmentFile source) throws CoreException;
+
+	/**
+	 * Changes the inclusion from the context of 'source' to point to this file, instead. 
+	 * The file 'source' must belong to the same fragment as this file.
+	 */
+	void transferContext(IIndexFragmentFile source) throws CoreException;
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragmentFileSet.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragmentFileSet.java
index 39eeb9d38bf..bfe5d1ed5cb 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragmentFileSet.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IIndexFragmentFileSet.java
@@ -26,6 +26,11 @@ public interface IIndexFragmentFileSet {
 	void add(IIndexFragmentFile fragFile);
 
 	/**
+	 * Removes the fragment file from the file-set.
+	 */
+	void remove(IIndexFragmentFile fragFile);
+
+	/**
 	 * Returns whether the file set contains the given file.
 	 */
 	boolean contains(IIndexFragmentFile file) throws CoreException;
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IWritableIndex.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IWritableIndex.java
index b2fd477791d..b0833880aae 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IWritableIndex.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IWritableIndex.java
@@ -6,20 +6,19 @@
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
- *    Markus Schorn - initial API and implementation
- *    Andrew Ferguson (Symbian)
- *    Sergey Prigogin (Google)
+ *     Markus Schorn - initial API and implementation
+ *     Andrew Ferguson (Symbian)
+ *     Sergey Prigogin (Google)
  *******************************************************************************/ 
 package org.eclipse.cdt.internal.core.index;
 
-import java.util.Collection;
-
 import org.eclipse.cdt.core.dom.ast.IASTName;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorIncludeStatement;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorStatement;
 import org.eclipse.cdt.core.index.IIndex;
 import org.eclipse.cdt.core.index.IIndexFile;
 import org.eclipse.cdt.core.index.IIndexFileLocation;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.internal.core.pdom.ASTFilePathResolver;
 import org.eclipse.cdt.internal.core.pdom.YieldableIndexLock;
 import org.eclipse.core.runtime.CoreException;
@@ -33,10 +32,19 @@ import org.eclipse.core.runtime.CoreException;
 public interface IWritableIndex extends IIndex {
 	
 	static class IncludeInformation {
-		public IASTPreprocessorIncludeStatement fStatement;
-		public IIndexFileLocation fLocation;
+		public final IASTPreprocessorIncludeStatement fStatement;
+		public final IIndexFileLocation fLocation;
+		public final ISignificantMacros fSignificantMacros;
+		public final boolean fIsContext;
 		public IIndexFragmentFile fTargetFile;
-		public boolean fIsContext= false;
+		
+		public IncludeInformation(IASTPreprocessorIncludeStatement stmt, 
+				IIndexFileLocation location, ISignificantMacros sig, boolean isContext) {
+			fStatement= stmt;
+			fSignificantMacros= sig;
+			fLocation= location;
+			fIsContext= isContext;
+		}
 	}
 	
 	/**
@@ -45,14 +53,21 @@ public interface IWritableIndex extends IIndex {
 	boolean isWritableFile(IIndexFile file);
 
 	/**
-	 * Returns a writable file for the given location and linkage, or null. This method
-	 * returns file-objects without content, also.
+	 * Returns a writable file for the given location, linkage, and the set of macro definitions,
+	 * or null. This method returns file objects without content, also.
 	 */
-	IIndexFragmentFile getWritableFile(int linkageID, IIndexFileLocation location) throws CoreException;
+	IIndexFragmentFile getWritableFile(int linkageID, IIndexFileLocation location,
+			ISignificantMacros macroDictionary) throws CoreException;
+
+	/**
+	 * Returns the writable files for the given location and linkage. This method
+	 * returns file objects without content, also.
+	 */
+	IIndexFragmentFile[] getWritableFiles(int linkageID, IIndexFileLocation location) throws CoreException;
 
 	/**
 	 * Returns the writable files for the given location in any linkage. This method
-	 * returns file-objects without content, also.
+	 * returns file objects without content, also.
 	 */
 	IIndexFragmentFile[] getWritableFiles(IIndexFileLocation location) throws CoreException;
 
@@ -62,21 +77,28 @@ public interface IWritableIndex extends IIndex {
 	 * @param a collection that receives IndexFileLocation objects for files that
 	 *     had the cleared file as a context. May be <code>null</code>.
 	 */
-	void clearFile(IIndexFragmentFile file, Collection<IIndexFileLocation> clearedContexts) throws CoreException;
+	void clearFile(IIndexFragmentFile file) throws CoreException;
 
 	/**
 	 * Creates a file object for the given location or returns an existing one.
+	 * @param linkageID the id of the linkage in which the file has been parsed.
+	 * @param location the IIndexFileLocation representing the location of the file
+	 * @param macroDictionary The names and definitions of the macros used to disambiguate between
+	 *     variants of the file contents corresponding to different inclusion points.
+	 * @return A created or an existing file.  
 	 */
-	IIndexFragmentFile addFile(int linkageID, IIndexFileLocation location) throws CoreException;
+	IIndexFragmentFile addFile(int linkageID, IIndexFileLocation location,
+			ISignificantMacros macroDictionary) throws CoreException;
 
 	/**
 	 * Creates a uncommitted file object for the given location.
 	 */
-	IIndexFragmentFile addUncommittedFile(int linkageID, IIndexFileLocation location) throws CoreException;
+	IIndexFragmentFile addUncommittedFile(int linkageID, IIndexFileLocation location,
+			ISignificantMacros macroDictionary) throws CoreException;
 
 	/**
 	 * Makes an uncommitted file that was created earlier by calling
-	 * {@link #addUncommittedFile(int, IIndexFileLocation)} method visible in the index.
+	 * {@link #addUncommittedFile(int, IIndexFileLocation, ISignificantMacros)} method visible in the index.
 	 *
 	 * @return The file that was updated.
 	 * @throws CoreException
@@ -106,20 +128,20 @@ public interface IWritableIndex extends IIndex {
 	/**
 	 * Acquires a write lock, while giving up a certain amount of read locks.
 	 */
-	void acquireWriteLock(int giveupReadLockCount) throws InterruptedException;
+	void acquireWriteLock() throws InterruptedException;
 
 	/**
 	 * Releases a write lock, reestablishing a certain amount of read locks.
 	 * Fully equivalent to <code>releaseWriteLock(int, true)</code>.
 	 */
-	void releaseWriteLock(int establishReadLockCount);
+	void releaseWriteLock();
 
 	/**
 	 * Releases a write lock, reestablishing a certain amount of read locks.
 	 * @param establishReadLockCount amount of read-locks to establish.
 	 * @param flushDatabase when true the changes are flushed to disk.
 	 */
-	void releaseWriteLock(int establishReadLockCount, boolean flushDatabase);
+	void releaseWriteLock(boolean flushDatabase);
 	
 	/**
 	 * Resets the counters for cache-hits
@@ -156,4 +178,16 @@ public interface IWritableIndex extends IIndex {
 	 * Clears the result cache, caller needs to hold a write-lock.
 	 */
 	void clearResultCache();
+
+	/**
+	 * Changes the inclusions pointing to 'source' to point to 'target', instead. 
+	 * Both files must belong to the writable fragment.
+	 */
+	void transferIncluders(IIndexFragmentFile source, IIndexFragmentFile target) throws CoreException;
+
+	/**
+	 * Changes the inclusion from the context of 'source' to point to 'target', instead. 
+	 * Both files must belong to the writable fragment.
+	 */
+	void transferContext(IIndexFragmentFile source, IIndexFragmentFile target) throws CoreException;
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IWritableIndexFragment.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IWritableIndexFragment.java
index 5aeea79d6d9..0996a4ea8c9 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IWritableIndexFragment.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IWritableIndexFragment.java
@@ -6,18 +6,17 @@
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
- *    Markus Schorn - initial API and implementation
- *    Andrew Ferguson (Symbian)
- *    Sergey Prigogin (Google)
+ *     Markus Schorn - initial API and implementation
+ *     Andrew Ferguson (Symbian)
+ *     Sergey Prigogin (Google)
 ******************************************************************************/ 
 
 package org.eclipse.cdt.internal.core.index;
 
-import java.util.Collection;
-
 import org.eclipse.cdt.core.dom.ast.IASTName;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorStatement;
 import org.eclipse.cdt.core.index.IIndexFileLocation;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.internal.core.index.IWritableIndex.IncludeInformation;
 import org.eclipse.cdt.internal.core.pdom.ASTFilePathResolver;
 import org.eclipse.cdt.internal.core.pdom.YieldableIndexLock;
@@ -39,28 +38,32 @@ public interface IWritableIndexFragment extends IIndexFragment {
 	 * @param a collection that receives IndexFileLocation objects for files that
 	 *     had the cleared file as a context.
 	 */
-	void clearFile(IIndexFragmentFile file, Collection<IIndexFileLocation> contextsRemoved) throws CoreException;
+	void clearFile(IIndexFragmentFile file) throws CoreException;
 
 	/**
 	 * Creates a file object for the given location and linkage or returns an existing one.
 	 * @param fileLocation an IIndexFileLocation representing the location of the file.
+	 * @param sigMacros the macro definitions at the inclusion point. 
 	 * @return the existing IIndexFragmentFile for this location, or a newly created one. 
 	 * @throws CoreException
 	 */
-	IIndexFragmentFile addFile(int linkageID, IIndexFileLocation fileLocation) throws CoreException;
+	IIndexFragmentFile addFile(int linkageID, IIndexFileLocation fileLocation,
+			ISignificantMacros sigMacros) throws CoreException;
 
 	/**
 	 * Creates a file object for the given location and linkage. The created file object is not added to
 	 * the file index.
 	 * @param fileLocation an IIndexFileLocation representing the location of the file.
+	 * @param sigMacros the macro definitions at the inclusion point. 
 	 * @return a newly created IIndexFragmentFile. 
 	 * @throws CoreException
 	 */
-	IIndexFragmentFile addUncommittedFile(int linkageID, IIndexFileLocation fileLocation) throws CoreException;
+	IIndexFragmentFile addUncommittedFile(int linkageID, IIndexFileLocation fileLocation,
+			ISignificantMacros sigMacros) throws CoreException;
 
 	/**
 	 * Makes an uncommitted file that was created earlier by calling
-	 * {@link #addUncommittedFile(int, IIndexFileLocation)} method visible in the index.
+	 * {@link #addUncommittedFile(int, IIndexFileLocation, ISignificantMacros)} method visible in the index.
      *
 	 * @return The file that was updated.
 	 * @throws CoreException
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IndexBasedFileContentProvider.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IndexBasedFileContentProvider.java
index b08259e370c..ccfc664eed6 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IndexBasedFileContentProvider.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IndexBasedFileContentProvider.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2005, 2010 QNX Software Systems and others.
+ * Copyright (c) 2005, 2011 QNX Software Systems and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -11,16 +11,21 @@
  *     Andrew Ferguson (Symbian)
  *     Anton Leherbauer (Wind River Systems)
  *     IBM Corporation
+ *     Sergey Prigogin (Google)
  *******************************************************************************/
 package org.eclipse.cdt.internal.core.index;
 
 import java.util.ArrayList;
-import java.util.Arrays;
+import java.util.Collection;
+import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 
 import org.eclipse.cdt.core.CCorePlugin;
+import org.eclipse.cdt.core.dom.ast.IFileNomination;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPUsingDirective;
 import org.eclipse.cdt.core.index.IIndex;
 import org.eclipse.cdt.core.index.IIndexFile;
@@ -28,7 +33,9 @@ import org.eclipse.cdt.core.index.IIndexFileLocation;
 import org.eclipse.cdt.core.index.IIndexInclude;
 import org.eclipse.cdt.core.index.IIndexMacro;
 import org.eclipse.cdt.core.parser.IncludeFileContentProvider;
+import org.eclipse.cdt.internal.core.parser.IMacroDictionary;
 import org.eclipse.cdt.internal.core.parser.scanner.InternalFileContent;
+import org.eclipse.cdt.internal.core.parser.scanner.InternalFileContent.FileVersion;
 import org.eclipse.cdt.internal.core.parser.scanner.InternalFileContent.InclusionKind;
 import org.eclipse.cdt.internal.core.parser.scanner.InternalFileContentProvider;
 import org.eclipse.cdt.internal.core.pdom.ASTFilePathResolver;
@@ -37,8 +44,7 @@ import org.eclipse.cdt.internal.core.pdom.AbstractIndexerTask.IndexFileContent;
 import org.eclipse.core.runtime.CoreException;
 
 /**
- * Code reader factory, that fakes code readers for header files already stored in the 
- * index.
+ * Code reader factory, that fakes code readers for header files already stored in the index.
  */
 public final class IndexBasedFileContentProvider extends InternalFileContentProvider {
 	private static final class NeedToParseException extends Exception {}
@@ -46,14 +52,14 @@ public final class IndexBasedFileContentProvider extends InternalFileContentProv
 
 	private final IIndex fIndex;
 	private int fLinkage;
-	private Set<IIndexFileLocation> fIncludedFiles= new HashSet<IIndexFileLocation>();
 	/** The fall-back code reader factory used in case a header file is not indexed */
 	private final InternalFileContentProvider fFallBackFactory;
 	private final ASTFilePathResolver fPathResolver;
 	private final AbstractIndexerTask fRelatedIndexerTask;
-	private boolean fSupportFillGapFromContextToHeader= false;
 	private long fFileSizeLimit= 0;
-	
+	private IIndexFile[] fContextToHeaderGap;
+	private final Map<IIndexFileLocation, IFileNomination> fPragmaOnce= new HashMap<IIndexFileLocation, IFileNomination>();
+
 	public IndexBasedFileContentProvider(IIndex index,
 			ASTFilePathResolver pathResolver, int linkage, IncludeFileContentProvider fallbackFactory) {
 		this(index, pathResolver, linkage, fallbackFactory, null);
@@ -68,8 +74,8 @@ public final class IndexBasedFileContentProvider extends InternalFileContentProv
 		fLinkage= linkage;
 	}
 
-	public void setSupportFillGapFromContextToHeader(boolean val) {
-		fSupportFillGapFromContextToHeader= val;
+	public void setContextToHeaderGap(IIndexFile[] ctxToHeader) {
+		fContextToHeaderGap= ctxToHeader;
 	}
 	
 	public void setFileSizeLimit(long limit) {
@@ -79,60 +85,63 @@ public final class IndexBasedFileContentProvider extends InternalFileContentProv
 	public void setLinkage(int linkageID) {
 		fLinkage= linkageID;
 	}
-
-	public void cleanupAfterTranslationUnit() {
-		fIncludedFiles.clear();
-	}
 	
 	@Override
-	public boolean getInclusionExists(String path) {
-		return fPathResolver.doesIncludeFileExist(path); 
+	public void resetForTranslationUnit() {
+		super.resetForTranslationUnit();
+		fPragmaOnce.clear();
 	}
-	
+
+	/** 
+	 * Reports detection of pragma once semantics.
+	 */
 	@Override
-	public void reportTranslationUnitFile(String path) {
-		IIndexFileLocation ifl= fPathResolver.resolveASTPath(path);
-		fIncludedFiles.add(ifl);
+	public void reportPragmaOnceSemantics(String filePath, IFileNomination nom) {
+		fPragmaOnce.put(fPathResolver.resolveIncludeFile(filePath), nom);
 	}
 
+	/**
+	 * Returns whether the given file has been included with pragma once semantics.
+	 */
 	@Override
-	public Boolean hasFileBeenIncludedInCurrentTranslationUnit(String path) {
-		IIndexFileLocation ifl= fPathResolver.resolveASTPath(path);
-		return fIncludedFiles.contains(ifl);
+	public IFileNomination isIncludedWithPragmaOnceSemantics(String filePath) {
+		return fPragmaOnce.get(fPathResolver.resolveIncludeFile(filePath));
+	}
+
+	@Override
+	public boolean getInclusionExists(String path) {
+		return fPathResolver.doesIncludeFileExist(path); 
 	}
 	
+	
 	@Override
-	public InternalFileContent getContentForInclusion(String path) {
+	public InternalFileContent getContentForInclusion(String path, IMacroDictionary macroDictionary) {
 		IIndexFileLocation ifl= fPathResolver.resolveIncludeFile(path);
 		if (ifl == null) {
 			return null;
 		}
+
 		path= fPathResolver.getASTPath(ifl);
-		
-		// Include files once, only.
-		if (!fIncludedFiles.add(ifl)) {
-			return new InternalFileContent(path, InclusionKind.SKIP_FILE);
-		}
-		
 		try {
-			IIndexFile file= fIndex.getFile(fLinkage, ifl);
+			IIndexFile file = selectIndexFile(macroDictionary, ifl);
 			if (file != null) {
 				try {
 					List<IIndexFile> files= new ArrayList<IIndexFile>();
 					List<IIndexMacro> macros= new ArrayList<IIndexMacro>();
 					List<ICPPUsingDirective> directives= new ArrayList<ICPPUsingDirective>();
-					Set<IIndexFileLocation> ifls= new HashSet<IIndexFileLocation>();
-					collectFileContent(file, ifls, files, macros, directives, false);
-					// add included files only, if no exception was thrown
-					fIncludedFiles.addAll(ifls);
-					return new InternalFileContent(path, macros, directives, files);
+					Map<IIndexFileLocation, IFileNomination> newPragmaOnce= new HashMap<IIndexFileLocation, IFileNomination>();
+					LinkedHashSet<IIndexFile> preLoaded= new LinkedHashSet<IIndexFile>();
+					collectFileContent(file, null, newPragmaOnce, preLoaded, files, macros, directives, null);
+					// Report pragma once inclusions, only if no exception was thrown.
+					fPragmaOnce.putAll(newPragmaOnce);
+					return new InternalFileContent(path, macros, directives, files, toList(preLoaded));
 				} catch (NeedToParseException e) {
 				}
-			}
+			} 
 		} catch (CoreException e) {
 			CCorePlugin.log(e);
 		}
-		
+
 		// Skip large files
 		if (fFileSizeLimit > 0 && fPathResolver.getFileSize(path) > fFileSizeLimit) {
 			return new InternalFileContent(path, InclusionKind.SKIP_FILE);
@@ -147,6 +156,26 @@ public final class IndexBasedFileContentProvider extends InternalFileContentProv
 		return null;
 	}
 
+	public List<String> toPathList(Collection<IIndexFileLocation> newPragmaOnce) {
+		List<String> newPragmaOncePaths= new ArrayList<String>(newPragmaOnce.size());
+		for (IIndexFileLocation l : newPragmaOnce) {
+			newPragmaOncePaths.add(fPathResolver.getASTPath(l));
+		}
+		return newPragmaOncePaths;
+	}
+
+	public IIndexFile selectIndexFile(IMacroDictionary macroDictionary, IIndexFileLocation ifl)
+			throws CoreException {
+		if (fRelatedIndexerTask != null)
+			return fRelatedIndexerTask.selectIndexFile(fLinkage, ifl, macroDictionary);
+		
+		for (IIndexFile file : fIndex.getFiles(fLinkage, ifl)) {
+			if (macroDictionary.satisfies(file.getSignificantMacros()))
+				return file;
+		}
+		return null;
+	}
+
 	@Override
 	public InternalFileContent getContentForInclusion(IIndexFileLocation ifl, String astPath) {
 		if (fFallBackFactory != null) {
@@ -155,145 +184,122 @@ public final class IndexBasedFileContentProvider extends InternalFileContentProv
 		return null;
 	}
 
-	private void collectFileContent(IIndexFile file, Set<IIndexFileLocation> ifls, List<IIndexFile> files,
-			List<IIndexMacro> macros, List<ICPPUsingDirective> usingDirectives, boolean checkIncluded)
-			throws CoreException, NeedToParseException {
+	private boolean collectFileContent(IIndexFile file, IIndexFile stopAt,
+			Map<IIndexFileLocation, IFileNomination> newPragmaOnce,
+			LinkedHashSet<IIndexFile> preLoaded, List<IIndexFile> files,
+			List<IIndexMacro> macros, List<ICPPUsingDirective> usingDirectives,
+			Set<IIndexFile> preventRecursion) throws CoreException, NeedToParseException {
+		if (file.equals(stopAt))
+			return true;
+		
 		IIndexFileLocation ifl= file.getLocation();
-		if (!ifls.add(ifl) || (checkIncluded && fIncludedFiles.contains(ifl))) {
-			return;
+		if (newPragmaOnce.containsKey(ifl))
+			return false;
+		if (file.hasPragmaOnceSemantics()) 
+			newPragmaOnce.put(ifl, file);
+		
+		if (preventRecursion != null) {
+			if (fPragmaOnce.containsKey(ifl)) 
+				return false;
+		} else {
+			preventRecursion= new HashSet<IIndexFile>();
 		}
-		IndexFileContent content;
+		if (!preventRecursion.add(file))
+			return false;
+
+		final ICPPUsingDirective[] uds;
+		final Object[] pds;
 		if (fRelatedIndexerTask != null) {
-			content= fRelatedIndexerTask.getFileContent(fLinkage, ifl);
-			if (content == null) {
+			IndexFileContent content= fRelatedIndexerTask.getFileContent(fLinkage, ifl, file);
+			if (content == null) 
 				throw new NeedToParseException();
-			}
+			uds= content.getUsingDirectives();
+			pds= content.getPreprocessingDirectives();
 		} else {
-			content= new IndexFileContent();
-			content.setPreprocessorDirectives(file.getIncludes(), file.getMacros());
-			content.setUsingDirectives(file.getUsingDirectives());
+			uds= file.getUsingDirectives();
+			pds= IndexFileContent.merge(file.getIncludes(), file.getMacros());
 		}
 		
 		files.add(file);
-		usingDirectives.addAll(Arrays.asList(content.getUsingDirectives()));
-		Object[] dirs= content.getPreprocessingDirectives();
-		for (Object d : dirs) {
+		if (!file.hasPragmaOnceSemantics()) {
+			preLoaded.add(file);
+		}
+		int udx= 0;
+		for (Object d : pds) {
 			if (d instanceof IIndexMacro) {
 				macros.add((IIndexMacro) d);
 			} else if (d instanceof IIndexInclude) {
+				IIndexInclude inc= (IIndexInclude) d;
 				IIndexFile includedFile= fIndex.resolveInclude((IIndexInclude) d);
 				if (includedFile != null) {
-					collectFileContent(includedFile, ifls, files, macros, usingDirectives, true);
+					// Add in using directives that appear before the inclusion
+					final int offset= inc.getNameOffset();
+					for (; udx < uds.length && uds[udx].getPointOfDeclaration() <= offset; udx++) {
+						usingDirectives.add(uds[udx]);
+					}
+					if (collectFileContent(includedFile, stopAt, newPragmaOnce, preLoaded, files, macros, usingDirectives, preventRecursion))
+						return true;
 				}
 			}
 		}
+		// Add in remaining using directives
+		for (; udx < uds.length; udx++) {
+			usingDirectives.add(uds[udx]);
+		}
+		preventRecursion.remove(file);
+		return false;
 	}
 
 	@Override
-	public InternalFileContent getContentForContextToHeaderGap(String path) {
-		if (!fSupportFillGapFromContextToHeader) {
-			return null;
-		}
-		
-		IIndexFileLocation ifl= fPathResolver.resolveASTPath(path);
-		if (ifl == null) {
+	public InternalFileContent getContentForContextToHeaderGap(String path,
+			IMacroDictionary macroDictionary) {
+		if (fContextToHeaderGap == null) {
 			return null;
 		}
 		
 		try {
-			IIndexFile targetFile= fIndex.getFile(fLinkage, ifl);
-			if (targetFile == null) {
-				return null;
-			}
-			
-			IIndexFile contextFile= findContext(targetFile);
-			if (contextFile == targetFile || contextFile == null) {
+			IIndexFile contextFile= fContextToHeaderGap[0];
+			IIndexFile targetFile = fContextToHeaderGap[1];
+			if (contextFile == null || targetFile == null ||  contextFile == targetFile) 
 				return null;
-			}
-			
-			HashSet<IIndexFile> filesIncluded= new HashSet<IIndexFile>();
+
+			Map<IIndexFileLocation, IFileNomination> newPragmaOnce= new HashMap<IIndexFileLocation, IFileNomination>();
+			List<IIndexFile> filesIncluded= new ArrayList<IIndexFile>();
 			ArrayList<IIndexMacro> macros= new ArrayList<IIndexMacro>();
 			ArrayList<ICPPUsingDirective> directives= new ArrayList<ICPPUsingDirective>();
-			if (!collectFileContentForGap(contextFile, ifl, filesIncluded, macros, directives)) {
+			LinkedHashSet<IIndexFile> preLoaded= new LinkedHashSet<IIndexFile>();
+			try {
+				if (!collectFileContent(contextFile, targetFile, newPragmaOnce, preLoaded,
+						filesIncluded, macros, directives, new HashSet<IIndexFile>())) {
+					return null;
+				}
+			} catch (NeedToParseException e) {
 				return null;
 			}
 
-			// mark the files in the gap as included
-			for (IIndexFile file : filesIncluded) {
-				fIncludedFiles.add(file.getLocation());
-			}
-			return new InternalFileContent(GAP, macros, directives, new ArrayList<IIndexFile>(filesIncluded));
+			// Report pragma once inclusions.
+			fPragmaOnce.putAll(newPragmaOnce);
+			return new InternalFileContent(GAP, macros, directives, filesIncluded, toList(preLoaded));
 		} catch (CoreException e) {
 			CCorePlugin.log(e);
 		}
 		return null;
 	}
 
-	private IIndexFile findContext(IIndexFile file) throws CoreException {
-		final HashSet<IIndexFile> ifiles= new HashSet<IIndexFile>();
-		ifiles.add(file);
-		IIndexInclude include= file.getParsedInContext();
-		while (include != null) {
-			final IIndexFile context= include.getIncludedBy();
-			if (!ifiles.add(context)) {
-				return file;
-			}
-			file= context;
-			include= context.getParsedInContext();
-		}
-		return file;
-	}
-
-	private boolean collectFileContentForGap(IIndexFile from, IIndexFileLocation to,
-			Set<IIndexFile> filesIncluded, List<IIndexMacro> macros,
-			List<ICPPUsingDirective> directives) throws CoreException {
-		final IIndexFileLocation ifl= from.getLocation();
-		if (ifl.equals(to)) {
-			return true;
+	private List<FileVersion> toList(LinkedHashSet<IIndexFile> preLoaded) throws CoreException {
+		List<FileVersion> result= new ArrayList<InternalFileContent.FileVersion>(preLoaded.size());
+		for (IIndexFile file : preLoaded) {
+			String path= fPathResolver.getASTPath(file.getLocation());
+			result.add(new FileVersion(path, file.getSignificantMacros()));
 		}
-
-		if (fIncludedFiles.contains(ifl) || !filesIncluded.add(from)) {
-			return false;
-		}
-
-		final IIndexInclude[] ids= from.getIncludes();
-		final IIndexMacro[] ms= from.getMacros();
-		final Object[] dirs= IndexFileContent.merge(ids, ms);
-		IIndexInclude success= null;
-		for (Object d : dirs) {
-			if (d instanceof IIndexMacro) {
-				macros.add((IIndexMacro) d);
-			} else if (d instanceof IIndexInclude) {
-				IIndexFile includedFile= fIndex.resolveInclude((IIndexInclude) d);
-				if (includedFile != null) {
-					if (collectFileContentForGap(includedFile, to, filesIncluded, macros, directives)) {
-						success= (IIndexInclude) d;
-						break;
-					}
-				}
-			}
-		}
-
-		final ICPPUsingDirective[] uds= from.getUsingDirectives();
-		if (success == null) {
-			directives.addAll(Arrays.asList(uds));
-			return false;
-		}
-			
-		final int offset= success.getNameOffset();
-		for (ICPPUsingDirective ud : uds) {
-			if (ud.getPointOfDeclaration() > offset)
-				break;
-			directives.add(ud);
-		}
-		return true;
+		return result;
 	}
 
-	public IIndexFile findIndexFile(InternalFileContent fc) throws CoreException {
+	public IIndexFile[] findIndexFiles(InternalFileContent fc) throws CoreException {
 		IIndexFileLocation ifl = fPathResolver.resolveASTPath(fc.getFileLocation());
 		if (ifl != null) {
-			return fIndex.getFile(fLinkage, ifl);
+			return fIndex.getFiles(fLinkage, ifl);
 		}
-		return null;
+		return IIndexFile.EMPTY_FILE_ARRAY;
 	}
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IndexFileSet.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IndexFileSet.java
index d244250377d..395eefc0664 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IndexFileSet.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IndexFileSet.java
@@ -40,6 +40,15 @@ public class IndexFileSet implements IIndexFileSet {
 		subSet.add(fragFile);
 	}
 
+	public void remove(IIndexFile indexFile) {
+		final IIndexFragmentFile fragFile = (IIndexFragmentFile) indexFile;
+		final IIndexFragment frag= fragFile.getIndexFragment();
+		IIndexFragmentFileSet subSet= fSubSets.get(frag);		
+		if (subSet != null) {
+			subSet.remove(fragFile);
+		}
+	}
+
 	public boolean containsDeclaration(IIndexBinding binding) {
 		return containsDeclaration(binding, false);
 	}
@@ -163,6 +172,10 @@ public class IndexFileSet implements IIndexFileSet {
 				public void add(IIndexFile indexFile) {
 					Assert.isLegal(false);
 				}
+
+				public void remove(IIndexFile indexFile) {
+					Assert.isLegal(false);
+				}
 			};
 		}
 		return fInverse;
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/WritableCIndex.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/WritableCIndex.java
index 8bd8489a716..0a0526da2c5 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/WritableCIndex.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/WritableCIndex.java
@@ -12,12 +12,11 @@
  *******************************************************************************/ 
 package org.eclipse.cdt.internal.core.index;
 
-import java.util.Collection;
-
 import org.eclipse.cdt.core.dom.ast.IASTName;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorStatement;
 import org.eclipse.cdt.core.index.IIndexFile;
 import org.eclipse.cdt.core.index.IIndexFileLocation;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.internal.core.pdom.ASTFilePathResolver;
 import org.eclipse.cdt.internal.core.pdom.YieldableIndexLock;
 import org.eclipse.core.runtime.CoreException;
@@ -43,20 +42,27 @@ public class WritableCIndex extends CIndex implements IWritableIndex {
 		return fWritableFragment;
 	}
 	
-	public IIndexFragmentFile getWritableFile(int linkageID, IIndexFileLocation location) throws CoreException {
-		return fWritableFragment.getFile(linkageID, location);
+	public IIndexFragmentFile getWritableFile(int linkageID, IIndexFileLocation location,
+			ISignificantMacros macroDictionary) throws CoreException {
+		return fWritableFragment.getFile(linkageID, location, macroDictionary);
 	}
-	
+
+	public IIndexFragmentFile[] getWritableFiles(int linkageID, IIndexFileLocation location) throws CoreException {
+		return fWritableFragment.getFiles(linkageID, location);
+	}
+
 	public IIndexFragmentFile[] getWritableFiles(IIndexFileLocation location) throws CoreException {
 		return fWritableFragment.getFiles(location);
 	}
 
-	public IIndexFragmentFile addFile(int linkageID, IIndexFileLocation location) throws CoreException {
-		return fWritableFragment.addFile(linkageID, location);
+	public IIndexFragmentFile addFile(int linkageID, IIndexFileLocation location,
+			ISignificantMacros macroDictionary) throws CoreException {
+		return fWritableFragment.addFile(linkageID, location, macroDictionary);
 	}
 
-	public IIndexFragmentFile addUncommittedFile(int linkageID, IIndexFileLocation location) throws CoreException {
-		return fWritableFragment.addUncommittedFile(linkageID, location);
+	public IIndexFragmentFile addUncommittedFile(int linkageID, IIndexFileLocation location,
+			ISignificantMacros macroDictionary) throws CoreException {
+		return fWritableFragment.addUncommittedFile(linkageID, location, macroDictionary);
 	}
 
 	public IIndexFragmentFile commitUncommittedFile() throws CoreException {
@@ -78,9 +84,10 @@ public class WritableCIndex extends CIndex implements IWritableIndex {
 		if (!isWritableFragment(indexFragment)) {
 			assert false : "Attempt to update file of read-only fragment"; //$NON-NLS-1$
 		} else {
-			for (IncludeInformation ii : includes) {
-				if (ii.fLocation != null) {
-					ii.fTargetFile= addFile(linkageID, ii.fLocation);
+			for (IncludeInformation include : includes) {
+				if (include.fLocation != null) {
+					include.fTargetFile= addFile(linkageID, include.fLocation,
+							include.fSignificantMacros);
 				}
 			}
 			((IWritableIndexFragment) indexFragment).addFileContent(file, includes, macros, names, resolver, lock);
@@ -96,12 +103,12 @@ public class WritableCIndex extends CIndex implements IWritableIndex {
 				isWritableFragment(((IIndexFragmentFile)file).getIndexFragment());
 	}
 	
-	public void clearFile(IIndexFragmentFile file, Collection<IIndexFileLocation> clearedContexts) throws CoreException {
+	public void clearFile(IIndexFragmentFile file) throws CoreException {
 		IIndexFragment indexFragment = file.getIndexFragment();
 		if (!isWritableFragment(indexFragment)) {
 			assert false : "Attempt to clear file of read-only fragment"; //$NON-NLS-1$
 		} else {
-			((IWritableIndexFragment) indexFragment).clearFile(file, clearedContexts);
+			((IWritableIndexFragment) indexFragment).clearFile(file);
 		}
 	}
 
@@ -121,25 +128,25 @@ public class WritableCIndex extends CIndex implements IWritableIndex {
 			fThread= null;
 	}
 
-	public void acquireWriteLock(int giveupReadlockCount) throws InterruptedException {
+	public void acquireWriteLock() throws InterruptedException {
 		checkThread();
 		assert !fIsWriteLocked: "Multiple write locks is not allowed"; //$NON-NLS-1$
-		assert giveupReadlockCount == getReadLockCount(): "Unexpected read lock is not allowed"; //$NON-NLS-1$
 		
-		fWritableFragment.acquireWriteLock(giveupReadlockCount);
+		fWritableFragment.acquireWriteLock(getReadLockCount());
 		fIsWriteLocked= true;
 	}
 
-	public void releaseWriteLock(int establishReadlockCount) {
-		releaseWriteLock(establishReadlockCount, true);
+	public void releaseWriteLock() {
+		releaseWriteLock(true);
 	}
 
-	public void releaseWriteLock(int establishReadlockCount, boolean flush) {
+	public void releaseWriteLock(boolean flush) {
 		checkThread();
 		assert fIsWriteLocked: "No write lock to be released"; //$NON-NLS-1$
-		assert establishReadlockCount == getReadLockCount(): "Unexpected read lock is not allowed"; //$NON-NLS-1$
+		
 
 		// Bug 297641: Result cache of read only providers needs to be cleared.
+		int establishReadlockCount = getReadLockCount();
 		if (establishReadlockCount == 0) {
 			clearResultCache();
 		}
@@ -171,10 +178,23 @@ public class WritableCIndex extends CIndex implements IWritableIndex {
 		fWritableFragment.flush();
 	}
 
-	/* (non-Javadoc)
-	 * @see org.eclipse.cdt.internal.core.index.IWritableIndex#getDatabaseSizeBytes()
-	 */
 	public long getDatabaseSizeBytes() {
 		return fWritableFragment.getDatabaseSizeBytes();
 	}
+
+	public void transferIncluders(IIndexFragmentFile source, IIndexFragmentFile target) throws CoreException {
+		if (source == null || target == null || !isWritableFile(source) || !isWritableFile(target))
+			throw new IllegalArgumentException();
+		if (source.equals(target))
+			return;
+		target.transferIncluders(source);
+	}
+	
+	public void transferContext(IIndexFragmentFile source, IIndexFragmentFile target) throws CoreException {
+		if (source == null || target == null || !isWritableFile(source) || !isWritableFile(target))
+			throw new IllegalArgumentException();
+		if (source.equals(target))
+			return;
+		target.transferContext(source);
+	}
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/indexer/StandaloneIndexer.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/indexer/StandaloneIndexer.java
index dc38809eb7d..5203d4d7041 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/indexer/StandaloneIndexer.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/indexer/StandaloneIndexer.java
@@ -358,12 +358,12 @@ public abstract class StandaloneIndexer {
 	private void clearIndex() throws CoreException, InterruptedException {
 		IWritableIndex index= getIndex();
 		// First clear the pdom
-		index.acquireWriteLock(0);
+		index.acquireWriteLock();
 		try {
 			index.clear();
 		}
 		finally {
-			index.releaseWriteLock(0);
+			index.releaseWriteLock();
 		}
 	}
 	
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/indexer/StandaloneIndexerTask.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/indexer/StandaloneIndexerTask.java
index 082e4da6785..8cb4e0b6734 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/indexer/StandaloneIndexerTask.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/indexer/StandaloneIndexerTask.java
@@ -15,13 +15,8 @@ import java.text.NumberFormat;
 import java.util.Collection;
 import java.util.Iterator;
 
-import com.ibm.icu.text.MessageFormat;
-
 import org.eclipse.cdt.core.dom.ILinkage;
-import org.eclipse.cdt.core.model.AbstractLanguage;
-import org.eclipse.cdt.core.model.ILanguage;
 import org.eclipse.cdt.core.parser.IParserLogService;
-import org.eclipse.cdt.core.parser.IScannerInfo;
 import org.eclipse.cdt.internal.core.index.IWritableIndex;
 import org.eclipse.cdt.internal.core.pdom.AbstractIndexerTask;
 import org.eclipse.cdt.internal.core.pdom.IndexerProgress;
@@ -29,6 +24,8 @@ import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 
+import com.ibm.icu.text.MessageFormat;
+
 /**
  * A task for index updates.
  * 
@@ -112,15 +109,6 @@ public abstract class StandaloneIndexerTask extends AbstractIndexerTask {
 	}
 
 	@Override
-	final protected AbstractLanguage[] getLanguages(String filename) {
-		ILanguage l = fIndexer.getLanguageMapper().getLanguage(filename);
-		if (l instanceof AbstractLanguage) {
-			return new AbstractLanguage[] {(AbstractLanguage) l};
-		}
-		return new AbstractLanguage[0];
-	}
-	
-	@Override
 	protected final IWritableIndex createIndex() {
 		return fIndexer.getIndex();
 	}
@@ -249,20 +237,6 @@ public abstract class StandaloneIndexerTask extends AbstractIndexerTask {
 	protected void logException(Throwable e) {
 		trace(e.getMessage());
 	}
-
-	@SuppressWarnings("deprecation")
-	@Override
-	protected IScannerInfo createDefaultScannerConfig(int linkageID) {
-		IStandaloneScannerInfoProvider provider = fIndexer.getScannerInfoProvider();
-		if(provider != null)
-			return provider.getDefaultScannerInformation(linkageID);
-		
-		IScannerInfo scannerInfo = fIndexer.getScannerInfo();
-		if(scannerInfo != null)
-			return scannerInfo;
-		
-		return super.createDefaultScannerConfig(linkageID);
-	}
 	
 	/* (non-Javadoc)
 	 * @see org.eclipse.cdt.internal.core.pdom.AbstractIndexerTask#getLinkagesToParse()
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/CodeReaderFactoryAdapter.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/CodeReaderFactoryAdapter.java
index 39571347044..3ac9468aaab 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/CodeReaderFactoryAdapter.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/CodeReaderFactoryAdapter.java
@@ -45,7 +45,7 @@ public class CodeReaderFactoryAdapter extends AbstractCodeReaderFactory {
 	}
 
 	public org.eclipse.cdt.core.parser.CodeReader createCodeReaderForInclusion(String path) {
-		return CodeReaderAdapter.adapt(fDelegate.getContentForInclusion(path));
+		return CodeReaderAdapter.adapt(fDelegate.getContentForInclusion(path, null));
 	}
 
 	@Override
@@ -55,7 +55,7 @@ public class CodeReaderFactoryAdapter extends AbstractCodeReaderFactory {
 	}
 
 	public org.eclipse.cdt.core.parser.CodeReader createCodeReaderForTranslationUnit(String path) {
-		return CodeReaderAdapter.adapt(fDelegate.getContentForInclusion(path));
+		return CodeReaderAdapter.adapt(fDelegate.getContentForInclusion(path, null));
 	}
 
 	@Deprecated
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/EmptyFilesProvider.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/EmptyFilesProvider.java
index f016fcb7982..163488ec3e3 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/EmptyFilesProvider.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/EmptyFilesProvider.java
@@ -27,7 +27,8 @@ public class EmptyFilesProvider extends InternalFileContentProvider {
 	}
 
 	@Override
-	public InternalFileContent getContentForInclusion(String path) {
+	public InternalFileContent getContentForInclusion(String path, 
+			IMacroDictionary macroDictionary) {
 		if (!getInclusionExists(path))
 			return null;
 		
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/FileContentProviderAdapter.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/FileContentProviderAdapter.java
index 33d65e001f9..08406327aab 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/FileContentProviderAdapter.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/FileContentProviderAdapter.java
@@ -6,7 +6,7 @@
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
- *    Markus Schorn - initial API and implementation
+ *     Markus Schorn - initial API and implementation
  *******************************************************************************/ 
 package org.eclipse.cdt.internal.core.parser;
 
@@ -26,7 +26,7 @@ import org.eclipse.core.runtime.CoreException;
 public class FileContentProviderAdapter extends InternalFileContentProvider {
 
 	/**
-	 * @deprecated avoid using the adapter, its for backwards compatibility, only.
+	 * @deprecated avoid using the adapter, it's for backwards compatibility, only.
 	 */
 	@Deprecated
 	public static InternalFileContentProvider adapt(ICodeReaderFactory fileCreator) {
@@ -57,7 +57,7 @@ public class FileContentProviderAdapter extends InternalFileContentProvider {
 	}
 
 	@Override
-	public InternalFileContent getContentForInclusion(String path) {
+	public InternalFileContent getContentForInclusion(String path, IMacroDictionary macroDictionary) {
 		return (InternalFileContent) FileContent.adapt(fDelegate.createCodeReaderForInclusion(path));
 	}
 
@@ -72,5 +72,4 @@ public class FileContentProviderAdapter extends InternalFileContentProvider {
 		}
 		return null;
 	}
-
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/IMacroDictionary.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/IMacroDictionary.java
new file mode 100644
index 00000000000..a6f854960a2
--- /dev/null
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/IMacroDictionary.java
@@ -0,0 +1,23 @@
+/*******************************************************************************
+ * Copyright (c) 2011 Wind River Systems, Inc. and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Markus Schorn - initial API and implementation
+ *******************************************************************************/ 
+
+package org.eclipse.cdt.internal.core.parser;
+
+import org.eclipse.cdt.core.parser.ISignificantMacros;
+
+
+/**
+ * Interface for accessing the macro dictionary of the preprocessor.
+ */
+public interface IMacroDictionary {
+
+	boolean satisfies(ISignificantMacros significantMacros);
+}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/SavedFilesProvider.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/SavedFilesProvider.java
index 5dff2328055..0cea421a535 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/SavedFilesProvider.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/SavedFilesProvider.java
@@ -30,7 +30,8 @@ public class SavedFilesProvider extends InternalFileContentProvider {
 	}
 	
 	@Override
-	public InternalFileContent getContentForInclusion(String path) {
+	public InternalFileContent getContentForInclusion(String path,
+			IMacroDictionary macroDictionary) {
 		if (!getInclusionExists(path))
 			return null;
 		
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ASTPreprocessorNode.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ASTPreprocessorNode.java
index 23ca3939424..314e83a5751 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ASTPreprocessorNode.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ASTPreprocessorNode.java
@@ -6,7 +6,7 @@
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
- *    Markus Schorn - initial API and implementation
+ *     Markus Schorn - initial API and implementation
  *******************************************************************************/ 
 package org.eclipse.cdt.internal.core.parser.scanner;
 
@@ -40,11 +40,15 @@ import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit;
 import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit.IDependencyTree;
 import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit.IDependencyTree.IASTInclusionNode;
 import org.eclipse.cdt.core.dom.ast.IBinding;
+import org.eclipse.cdt.core.dom.ast.IFileNomination;
 import org.eclipse.cdt.core.dom.ast.IMacroBinding;
+import org.eclipse.cdt.core.index.IIndexFile;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.core.parser.IToken;
 import org.eclipse.cdt.core.parser.util.CharArrayUtils;
 import org.eclipse.cdt.internal.core.dom.parser.ASTNode;
 import org.eclipse.cdt.internal.core.dom.parser.ASTNodeSpecification;
+import org.eclipse.core.runtime.CoreException;
 
 /**
  * Models various AST-constructs obtained from the preprocessor.
@@ -188,7 +192,7 @@ class ASTIfndef extends ASTDirectiveWithCondition implements IASTPreprocessorIfn
 }
 
 class ASTIfdef extends ASTDirectiveWithCondition implements IASTPreprocessorIfdefStatement {
-	ASTMacroReferenceName fMacroRef;
+	private ASTMacroReferenceName fMacroRef;
 	public ASTIfdef(IASTTranslationUnit parent, int startNumber, int condNumber, int condEndNumber, boolean taken, IMacroBinding macro) {
 		super(parent, startNumber, condNumber, condEndNumber, taken);
 		if (macro != null) {
@@ -253,21 +257,33 @@ class ASTPragmaOperator extends ASTPragma {
 }
 
 class ASTInclusionStatement extends ASTPreprocessorNode implements IASTPreprocessorIncludeStatement {
+	private static final ISignificantMacros[] NO_VERSIONS = {};
+	
 	private final ASTPreprocessorName fName;
 	private final String fPath;
 	private final boolean fIsResolved;
 	private final boolean fIsSystemInclude;
 	private final boolean fFoundByHeuristics;
+	private final IFileNomination fNominationDelegate;
+	private boolean fPragmaOnce;
+	private boolean fCreatesAST;
+	private ISignificantMacros fSignificantMacros;
+	private ISignificantMacros[] fLoadedVersions = NO_VERSIONS;
+	private long fContentsHash;
 
 	public ASTInclusionStatement(IASTTranslationUnit parent, 
 			int startNumber, int nameStartNumber, int nameEndNumber, int endNumber,
-			char[] headerName, String filePath, boolean userInclude, boolean active, boolean heuristic) {
+			char[] headerName, String filePath, boolean userInclude, boolean active, boolean heuristic, 
+			IFileNomination nominationDelegate) {
 		super(parent, IASTTranslationUnit.PREPROCESSOR_STATEMENT, startNumber, endNumber);
-		fName= new ASTPreprocessorName(this, IASTPreprocessorIncludeStatement.INCLUDE_NAME, nameStartNumber, nameEndNumber, headerName, null);
+		fName= new ASTPreprocessorName(this, IASTPreprocessorIncludeStatement.INCLUDE_NAME,
+				nameStartNumber, nameEndNumber, headerName, null);
 		fPath= filePath == null ? "" : filePath; //$NON-NLS-1$
 		fIsResolved= filePath != null;
 		fIsSystemInclude= !userInclude;
 		fFoundByHeuristics= heuristic;
+		fSignificantMacros= ISignificantMacros.NONE;
+		fNominationDelegate= nominationDelegate;
 		if (!active) {
 			setInactive();
 		}
@@ -298,6 +314,69 @@ class ASTInclusionStatement extends ASTPreprocessorNode implements IASTPreproces
 	public boolean isResolvedByHeuristics() {
 		return fFoundByHeuristics;
 	}
+
+	public boolean hasPragmaOnceSemantics() {
+		if (fNominationDelegate != null) {
+			try {
+				return fNominationDelegate.hasPragmaOnceSemantics();
+			} catch (CoreException e) {
+			}
+		} 	
+		return fPragmaOnce;
+	}
+	
+	public void setPragamOnceSemantics(boolean value) {
+		assert fNominationDelegate == null;
+		fPragmaOnce= value;
+	}
+
+	public ISignificantMacros getSignificantMacros() {
+		if (fNominationDelegate != null) {
+			try {
+				return fNominationDelegate.getSignificantMacros();
+			} catch (CoreException e) {
+			}
+		} 	
+		return fSignificantMacros;
+	}
+	
+	public void setSignificantMacros(ISignificantMacros sig) {
+		assert sig != null;
+		assert fNominationDelegate == null;
+		fSignificantMacros= sig;
+	}
+
+	public void setLoadedVersions(ISignificantMacros[] versions) {
+		fLoadedVersions= versions;
+	}
+
+	public ISignificantMacros[] getLoadedVersions() {
+		return fLoadedVersions;
+	}
+	
+	public long getContentsHash() {
+		if (fNominationDelegate != null) {
+			return 0;
+		} 	
+		return fContentsHash;
+	}
+	
+	public void setContentsHash(long hash) {
+		assert fNominationDelegate == null;
+		fCreatesAST= true;
+		fContentsHash= hash;
+	}
+
+	public boolean createsAST() {
+		return fCreatesAST;
+	}
+	
+	public IIndexFile getImportedIndexFile() {
+		if (fNominationDelegate instanceof IIndexFile)
+			return (IIndexFile) fNominationDelegate;
+		
+		return null;
+	}
 }
 
 class ASTMacroDefinition extends ASTPreprocessorNode implements IASTPreprocessorObjectStyleMacroDefinition {
@@ -579,6 +658,10 @@ class ASTFileLocation implements IASTFileLocation {
 	public LocationCtxFile getLocationContext() {
 		return fLocationCtx;
 	}
+
+	public IASTPreprocessorIncludeStatement getContextInclusionStatement() {
+		return fLocationCtx.getInclusionStatement();
+	}
 }
 
 class ASTMacroExpansion extends ASTPreprocessorNode implements IASTPreprocessorMacroExpansion {
@@ -708,6 +791,10 @@ class ASTFileLocationForBuiltins implements IASTFileLocation {
 	public int getStartingLineNumber() {
 		return 0;
 	}
+
+	public IASTPreprocessorIncludeStatement getContextInclusionStatement() {
+		return null;
+	}
 }
 
 
@@ -723,4 +810,3 @@ class ASTImageLocation extends ASTFileLocationForBuiltins implements IASTImageLo
 		return fKind;
 	}
 }
-
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/CPreprocessor.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/CPreprocessor.java
index a832728cba2..3b3eeb9d3c4 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/CPreprocessor.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/CPreprocessor.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2004, 2010 IBM Corporation and others.
+ * Copyright (c) 2004, 2011 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -19,12 +19,17 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
+import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.dom.ast.IASTFileLocation;
 import org.eclipse.cdt.core.dom.ast.IASTName;
+import org.eclipse.cdt.core.dom.ast.IBinding;
+import org.eclipse.cdt.core.dom.ast.IFileNomination;
 import org.eclipse.cdt.core.dom.ast.IMacroBinding;
 import org.eclipse.cdt.core.dom.parser.IScannerExtensionConfiguration;
 import org.eclipse.cdt.core.index.IIndexMacro;
+import org.eclipse.cdt.core.parser.AbstractParserLogService;
 import org.eclipse.cdt.core.parser.EndOfFileException;
 import org.eclipse.cdt.core.parser.FileContent;
 import org.eclipse.cdt.core.parser.IExtendedScannerInfo;
@@ -34,6 +39,7 @@ import org.eclipse.cdt.core.parser.IPreprocessorDirective;
 import org.eclipse.cdt.core.parser.IProblem;
 import org.eclipse.cdt.core.parser.IScanner;
 import org.eclipse.cdt.core.parser.IScannerInfo;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.core.parser.IToken;
 import org.eclipse.cdt.core.parser.IncludeFileContentProvider;
 import org.eclipse.cdt.core.parser.Keywords;
@@ -42,16 +48,21 @@ import org.eclipse.cdt.core.parser.ParseError;
 import org.eclipse.cdt.core.parser.ParserLanguage;
 import org.eclipse.cdt.core.parser.util.CharArrayIntMap;
 import org.eclipse.cdt.core.parser.util.CharArrayMap;
+import org.eclipse.cdt.core.parser.util.CharArrayObjectMap;
+import org.eclipse.cdt.core.parser.util.CharArraySet;
 import org.eclipse.cdt.core.parser.util.CharArrayUtils;
 import org.eclipse.cdt.internal.core.dom.IIncludeFileResolutionHeuristics;
 import org.eclipse.cdt.internal.core.parser.EmptyFilesProvider;
+import org.eclipse.cdt.internal.core.parser.IMacroDictionary;
 import org.eclipse.cdt.internal.core.parser.scanner.ExpressionEvaluator.EvalException;
+import org.eclipse.cdt.internal.core.parser.scanner.InternalFileContent.FileVersion;
 import org.eclipse.cdt.internal.core.parser.scanner.InternalFileContent.InclusionKind;
 import org.eclipse.cdt.internal.core.parser.scanner.Lexer.LexerOptions;
 import org.eclipse.cdt.internal.core.parser.scanner.MacroDefinitionParser.InvalidMacroDefinitionException;
 import org.eclipse.cdt.internal.core.parser.scanner.ScannerContext.BranchKind;
 import org.eclipse.cdt.internal.core.parser.scanner.ScannerContext.CodeState;
 import org.eclipse.cdt.internal.core.parser.scanner.ScannerContext.Conditional;
+import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IAdaptable;
 
 /**
@@ -88,11 +99,42 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     private static final DynamicMacro __DATE__= new DateMacro("__DATE__".toCharArray()); //$NON-NLS-1$
     private static final DynamicMacro __TIME__ = new TimeMacro("__TIME__".toCharArray()); //$NON-NLS-1$
     private static final DynamicMacro __LINE__ = new LineMacro("__LINE__".toCharArray()); //$NON-NLS-1$
+	private static final char[] ONCE = "once".toCharArray(); //$NON-NLS-1$
 
-	private static final int NO_EXPANSION 		 = 0x01;
-	private static final int PROTECT_DEFINED 	 = 0x02;
-	private static final int STOP_AT_NL 		 = 0x04;
-	private static final int CHECK_NUMBERS 		 = 0x08;
+	static final int NO_EXPANSION 		 					= 0x01;
+	static final int PROTECT_DEFINED 	 					= 0x02;
+	static final int STOP_AT_NL 		 					= 0x04;
+	static final int CHECK_NUMBERS 		 					= 0x08;
+	static final int REPORT_SIGNIFICANT_MACROS 				= 0x10;
+	static final int IGNORE_UNDEFINED_SIGNIFICANT_MACROS 	= 0x20;
+
+	private static final int MAX_INCLUSION_DEPTH = 200;
+
+	private static final String TRACE_NO_GUARD = CCorePlugin.PLUGIN_ID + "/debug/scanner/missingIncludeGuards"; //$NON-NLS-1$
+
+
+	private final class MacroDictionary implements IMacroDictionary, ISignificantMacros.IVisitor {
+		public boolean satisfies(ISignificantMacros significantMacros) {
+			return significantMacros.accept(this);
+		}
+		
+		public boolean visitDefined(char[] macro) {
+			return isDefined(macro);
+		}
+
+		public boolean visitUndefined(char[] macro) {
+			return !isDefined(macro);
+		}
+
+		public boolean visitValue(char[] macro, char[] value) {
+			PreprocessorMacro m = fMacroDictionary.get(macro);
+			return m != null && CharArrayUtils.equals(m.getExpansion(), value);
+		}
+
+		private boolean isDefined(char[] macro) {
+			return fMacroDictionary.containsKey(macro);
+		}
+	}
 
 	private interface IIncludeFileTester<T> {
     	T checkFile(String path, boolean isHeuristicMatch, IncludeSearchPathElement onPath);
@@ -100,7 +142,13 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 
 	final private IIncludeFileTester<InternalFileContent> createCodeReaderTester= new IIncludeFileTester<InternalFileContent>() {
     	public InternalFileContent checkFile(String path, boolean isHeuristicMatch, IncludeSearchPathElement onPath) {
-			final InternalFileContent fc= fFileContentProvider.getContentForInclusion(path);
+			final InternalFileContent fc;
+			IFileNomination once= fFileContentProvider.isIncludedWithPragmaOnceSemantics(path);
+			if (once != null) {
+				fc= new InternalFileContent(path, InclusionKind.SKIP_FILE);
+			} else {
+				fc= fFileContentProvider.getContentForInclusion(path, fMacroDictionaryFacade);
+			}
 			if (fc != null) {
 				fc.setFoundByHeuristics(isHeuristicMatch);
 				fc.setFoundOnPath(onPath);
@@ -162,7 +210,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 	TokenSequence fInputToMacroExpansion= new TokenSequence(false);
 	TokenSequence fLineInputToMacroExpansion= new TokenSequence(true);
 
-    final private IParserLogService fLog;
+    final private AbstractParserLogService fLog;
     final private InternalFileContentProvider fFileContentProvider;
 
     private IIncludeFileResolutionHeuristics fIncludeFileResolutionHeuristics;
@@ -184,10 +232,9 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 
     // state information
     private final CharArrayMap<PreprocessorMacro> fMacroDictionary = new CharArrayMap<PreprocessorMacro>(512);
+	private final IMacroDictionary fMacroDictionaryFacade = new MacroDictionary();
     private final LocationMap fLocationMap;
-
-    /** Set of already included files */
-    private final HashSet<String> fAllIncludedFiles= new HashSet<String>();
+	private CharArraySet fPreventInclusion= new CharArraySet(0); 
 
 	private final Lexer fRootLexer;
 	private final ScannerContext fRootContext;
@@ -200,6 +247,12 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     private Token fLastToken;
 
 	private InternalFileContent fRootContent;
+	private boolean fHandledEndOfTranslationUnit;
+
+	// Detection of include guards used around an include directive
+	private char[] fExternIncludeGuard;
+	private Set<String> fTracedGuards; 
+
 
     public CPreprocessor(FileContent fileContent, IScannerInfo info, ParserLanguage language,
     		IParserLogService log, IScannerExtensionConfiguration configuration,
@@ -217,7 +270,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     		throw new IllegalArgumentException("Illegal file content object"); //$NON-NLS-1$
     	}
     		
-        fLog = log;
+        fLog = AbstractParserLogService.convert(log);
         fAdditionalNumericLiteralSuffixes= nonNull(configuration.supportAdditionalNumericLiteralSuffixes());
         fLexOptions.fSupportDollarInIdentifiers= configuration.support$InIdentifiers();
         fLexOptions.fSupportAtSignInIdentifiers= configuration.supportAtSignInIdentifiers();
@@ -239,17 +292,38 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
         setupMacroDictionary(configuration, info, language);		
 
         ILocationCtx ctx= fLocationMap.pushTranslationUnit(filePath, fRootContent.getSource());
-        fAllIncludedFiles.add(filePath);
-    	fFileContentProvider.reportTranslationUnitFile(filePath);
         fRootLexer= new Lexer(fRootContent.getSource(), fLexOptions, this, this);
         fRootContext= fCurrentContext= new ScannerContext(ctx, null, fRootLexer);
         if (info instanceof IExtendedScannerInfo) {
         	final IExtendedScannerInfo einfo= (IExtendedScannerInfo) info;
-        	fPreIncludedFiles= new String[][] {einfo.getMacroFiles(), einfo.getIncludeFiles()};
+        	fPreIncludedFiles= new String[][] { einfo.getMacroFiles(), einfo.getIncludeFiles() };
         }
+        fFileContentProvider.resetForTranslationUnit();
     }
+    
+	private char[] detectIncludeGuard(String filePath, AbstractCharArray source, ScannerContext ctx) {
+		final char[] guard = IncludeGuardDetection.detectIncludeGuard(source, fLexOptions, fPPKeywords);
+		if (guard != null) {
+			IFileNomination nom= fLocationMap.reportPragmaOnceSemantics(ctx.getLocationCtx());
+ 			fFileContentProvider.reportPragmaOnceSemantics(filePath, nom);
+			ctx.internalModification(guard);
+			ctx.setPragmaOnce(true);
+			return guard;
+		} else {
+			ctx.trackSignificantMacros();
+		}
+		if (ctx != fRootContext) {
+			if (fLog.isTracing(TRACE_NO_GUARD)) {
+				if (fTracedGuards == null)
+					fTracedGuards= new HashSet<String>();
+				if (fTracedGuards.add(filePath))
+					fLog.traceLog(TRACE_NO_GUARD, "No include guard in " + filePath); //$NON-NLS-1$
+			}
+		}
+		return null;
+	}
 
-    public void setSplitShiftROperator(boolean val) {
+	public void setSplitShiftROperator(boolean val) {
     	fSplitShiftRightOperator= val;
     }
 
@@ -371,15 +445,19 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 
 	private void beforeFirstFetchToken() {
 		if (fPreIncludedFiles != null) {
-    		handlePreIncludedFiles();
-    	}
-		final String location = fLocationMap.getTranslationUnitPath();
-		InternalFileContent content= fFileContentProvider.getContentForContextToHeaderGap(location);
+			handlePreIncludedFiles();
+			fPreIncludedFiles= null;
+		}
+        final String location = fLocationMap.getTranslationUnitPath();
+		InternalFileContent content= fFileContentProvider.getContentForContextToHeaderGap(location,
+				fMacroDictionaryFacade);
 		if (content != null && content.getKind() == InclusionKind.FOUND_IN_INDEX) {
-			processInclusionFromIndex(0, location, content);
+			processInclusionFromIndex(0, location, content, false);
 		}
-		fLocationMap.replacingFile(fFileContentProvider, fRootContent);
-		fRootContent= null;
+		
+        detectIncludeGuard(location, fRootContent.getSource(), fRootContext);
+		fLocationMap.parsingFile(fFileContentProvider, fRootContent);
+		fRootContent= null;		
 	}
 
     private void handlePreIncludedFiles() {
@@ -726,11 +804,23 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
         		
         	case IToken.tEND_OF_INPUT:
         		if (fCurrentContext == uptoEndOfCtx || uptoEndOfCtx == null) {
+        			if (fCurrentContext == fRootContext && !fHandledEndOfTranslationUnit 
+        					&& (options & STOP_AT_NL) == 0) {
+        				fHandledEndOfTranslationUnit= true;
+        				fLocationMap.endTranslationUnit(ppToken.getEndOffset(), fCurrentContext.getSignificantMacros()); 
+        			}
         			return ppToken;
         		}
-            	final ILocationCtx locationCtx = fCurrentContext.getLocationCtx();
+        		
+        		final ILocationCtx locationCtx = fCurrentContext.getLocationCtx();
+    			ASTInclusionStatement inc = locationCtx.getInclusionStatement();
+        		if (inc != null) {
+        			completeInclusion(inc); 
+        		}
             	fLocationMap.popContext(locationCtx);
-        		fCurrentContext= fCurrentContext.getParent();
+
+            	fCurrentContext.propagateSignificantMacros();
+				fCurrentContext= fCurrentContext.getParent();
         		assert fCurrentContext != null;
             	
         		ppToken= fCurrentContext.currentLexerToken();
@@ -781,7 +871,21 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
         }
     }
 
-    private void checkNumber(Token number, final boolean isFloat) {
+	private void completeInclusion(ASTInclusionStatement inc) {
+		final ISignificantMacros sig;
+		CharArrayObjectMap<char[]> sigMacros= fCurrentContext.getSignificantMacros();
+		if (sigMacros == null || sigMacros.isEmpty()) {
+			sig = ISignificantMacros.NONE;
+		} else {
+			sig = new SignificantMacros(sigMacros);
+		}
+		inc.setSignificantMacros(sig);
+		if (!inc.hasPragmaOnceSemantics()) {
+			fFileContentProvider.addLoadedVersions(inc.getPath(), fCurrentContext.getLoadedVersionCount(), sig);
+		}
+	}
+
+	private void checkNumber(Token number, final boolean isFloat) {
         final char[] image= number.getCharImage();
         boolean hasExponent = false;
 
@@ -1151,7 +1255,8 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     		}
     		break;
     	case IPreprocessorDirective.ppPragma:
-    		condOffset= lexer.nextToken().getOffset();
+    		Token pragmaToken= lexer.nextToken();
+    		condOffset= pragmaToken.getOffset();
     		condEndOffset= lexer.consumeLine(ORIGIN_PREPROCESSOR_DIRECTIVE);
     		// Missing argument
 			if (condEndOffset < condOffset) {
@@ -1160,6 +1265,10 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     		if (fCurrentContext.getCodeState() == CodeState.eActive) {
     			int endOffset= lexer.currentToken().getEndOffset();
     			fLocationMap.encounterPoundPragma(startOffset, condOffset, condEndOffset, endOffset);
+    			if (CharArrayUtils.equals(ONCE, pragmaToken.getCharImage())) {
+    				IFileNomination nom= fLocationMap.reportPragmaOnceSemantics(fCurrentContext.getLocationCtx());
+    				fFileContentProvider.reportPragmaOnceSemantics(getCurrentFilename(), nom);
+    			}
     		}
     		break;
     	case IPreprocessorDirective.ppIgnore:
@@ -1175,16 +1284,12 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     	}
     }
 
-    private boolean hasFileBeenIncluded(String location) {
-    	Boolean itHas= fFileContentProvider.hasFileBeenIncludedInCurrentTranslationUnit(location);
-    	if (itHas != null) {
-    		return itHas.booleanValue();
-    	}
-    	return fAllIncludedFiles.contains(location);
-    }
-    
 	private void executeInclude(final Lexer lexer, int poundOffset, boolean include_next,
 			boolean active, boolean withinExpansion) throws OffsetLimitReachedException {
+		// Make sure to clear the extern include guard.
+		final char[] externGuard= fExternIncludeGuard;
+		fExternIncludeGuard= null;
+
 		if (withinExpansion) {
 			final char[] name= lexer.currentToken().getCharImage();
 			final int endOffset = lexer.consumeLine(ORIGIN_PREPROCESSOR_DIRECTIVE);
@@ -1258,71 +1363,129 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 	    	}
 			return;
 		}
-
-		String path= null;
-		boolean reported= false;
-		boolean isHeuristic= false;
+		
+		if (active && fCurrentContext.getDepth() == MAX_INCLUSION_DEPTH || fPreventInclusion.containsKey(headerName)) {
+			handleProblem(IProblem.PREPROCESSOR_EXCEEDS_MAXIMUM_INCLUSION_DEPTH,
+            		lexer.getInputChars(poundOffset, condEndOffset), poundOffset, condEndOffset);
+			fPreventInclusion.put(headerName);
+			return;
+		}
 		
 		final String includeDirective = new String(headerName);
 		if (!active) {
-			// test if the include is inactive just because it was included before (bug 167100)
-			final IncludeResolution resolved= findInclusion(includeDirective, userInclude, include_next,
-					getCurrentFilename(), createPathTester);
-			if (resolved != null && hasFileBeenIncluded(resolved.fLocation)) {
-				path= resolved.fLocation;
-				isHeuristic= resolved.fHeuristic;
-			}
-		} else {
-			final InternalFileContent fi= findInclusion(includeDirective, userInclude, include_next,
-					getCurrentFilename(), createCodeReaderTester);
-			if (fi != null) {
-				path= fi.getFileLocation();
-				isHeuristic= fi.isFoundByHeuristics();
-				switch (fi.getKind()) {
-				case FOUND_IN_INDEX:
-					processInclusionFromIndex(poundOffset, path, fi);
-					break;
-				case USE_SOURCE:
-					AbstractCharArray source= fi.getSource();
-					if (source != null && !isCircularInclusion(path)) {
-						reported= true;
-						fAllIncludedFiles.add(path);
-						ILocationCtx ctx= fLocationMap.pushInclusion(poundOffset, nameOffsets[0], nameOffsets[1],
-								condEndOffset, source, path, headerName, userInclude, isHeuristic, fi.isSource());
-						ScannerContext fctx= new ScannerContext(ctx, fCurrentContext,
-								new Lexer(source, fLexOptions, this, this));
-						fctx.setFoundOnPath(fi.getFoundOnPath(), includeDirective);
-						fCurrentContext= fctx;
+			// Inactive include 
+			String path= null;
+			boolean isHeuristic= false;
+			IFileNomination nominationDelegate= null;
+			
+			if (externGuard != null) {
+				// #ifndef GUARD
+				//    #include "file.h"
+				// #endif
+				// When the extern guard matches we need to resolve the inclusion. We don't actually
+				// check whether the guard matches.
+				final IncludeResolution resolved= findInclusion(includeDirective, userInclude, include_next,
+						getCurrentFilename(), createPathTester);
+				if (resolved != null) {
+					nominationDelegate = fFileContentProvider.isIncludedWithPragmaOnceSemantics(resolved.fLocation);
+					if (nominationDelegate != null) {
+						path= resolved.fLocation;
+						isHeuristic= resolved.fHeuristic;
 					}
-					fLocationMap.replacingFile(fFileContentProvider, fi);
-					break;
-					
-				case SKIP_FILE:
-					break;
 				}
-			} else {
-				final int len = headerName.length + 2;
-				StringBuilder name= new StringBuilder(len);
-				name.append(userInclude ? '"' : '<');
-				name.append(headerName);
-				name.append(userInclude ? '"' : '>');
-
-				final char[] nameChars= new char[len];
-				name.getChars(0, len, nameChars, 0);
-				handleProblem(IProblem.PREPROCESSOR_INCLUSION_NOT_FOUND, nameChars, poundOffset, condEndOffset);
 			}
+			fLocationMap.encounterPoundInclude(poundOffset, nameOffsets[0], nameOffsets[1],
+					condEndOffset, headerName, path, userInclude, active, isHeuristic, nominationDelegate);
+			return;
 		}
-
-		if (!reported) {
+		
+		// Active include
+		final InternalFileContent fi= findInclusion(includeDirective, userInclude, include_next,
+				getCurrentFilename(), createCodeReaderTester);
+		if (fi == null) {
+			// Unresolved active include
+			final int len = headerName.length + 2;
+			StringBuilder name= new StringBuilder(len);
+			name.append(userInclude ? '"' : '<');
+			name.append(headerName);
+			name.append(userInclude ? '"' : '>');
+
+			final char[] nameChars= new char[len];
+			name.getChars(0, len, nameChars, 0);
+			handleProblem(IProblem.PREPROCESSOR_INCLUSION_NOT_FOUND, nameChars, poundOffset, condEndOffset);
 			fLocationMap.encounterPoundInclude(poundOffset, nameOffsets[0], nameOffsets[1],
-					condEndOffset, headerName, path, userInclude, active, isHeuristic);
+					condEndOffset, headerName, null, userInclude, active, false, null);
+			return;
+		}
+
+		// Resolved active include
+		final String path= fi.getFileLocation();
+		final boolean isHeuristic= fi.isFoundByHeuristics();
+		final boolean pragmaOnceContext= fCurrentContext.isPragmaOnce();
+
+		IFileNomination nominationDelegate= null;
+		ASTInclusionStatement stmt= null;
+		List<ISignificantMacros> loadedVerisons = null;
+		switch (fi.getKind()) {
+		case FOUND_IN_INDEX:
+			// Pulled in from index
+			nominationDelegate= fi.getFilesIncluded().get(0);
+			try {
+				ISignificantMacros sm = nominationDelegate.getSignificantMacros();
+				fCurrentContext.addSignificantMacros(sm);
+				if (pragmaOnceContext && !nominationDelegate.hasPragmaOnceSemantics()) 
+					loadedVerisons= fFileContentProvider.getLoadedVersions(path);
+			} catch (CoreException e) {
+			}
+			
+			processInclusionFromIndex(poundOffset, path, fi, true);
+			break;
+		case USE_SOURCE:
+			// Will be parsed
+			AbstractCharArray source= fi.getSource();
+			if (source != null) {
+				ILocationCtx ctx= fLocationMap.pushInclusion(poundOffset, nameOffsets[0], nameOffsets[1],
+						condEndOffset, source, path, headerName, userInclude, isHeuristic, fi.isSource());
+				ScannerContext fctx= new ScannerContext(ctx, fCurrentContext,
+						new Lexer(source, fLexOptions, this, this));
+				fctx.setFoundOnPath(fi.getFoundOnPath(), includeDirective);
+				detectIncludeGuard(path, source, fctx);
+				fCurrentContext= fctx;
+				stmt= ctx.getInclusionStatement();
+				stmt.setContentsHash(source.getContentsHash());
+				if (!fCurrentContext.isPragmaOnce()) {
+					// Track the loaded version count, even in a non-pragma-once context.
+					loadedVerisons= fFileContentProvider.getLoadedVersions(path);
+					fctx.setLoadedVersionCount(loadedVerisons.size());
+				}
+			}
+			fLocationMap.parsingFile(fFileContentProvider, fi);
+			break;
+
+		case SKIP_FILE:
+			// Already included or fast parsing mode.
+			break;
+		}
+		if (stmt == null) {
+			// Found in index or skipped.
+			stmt= fLocationMap.encounterPoundInclude(poundOffset, nameOffsets[0], nameOffsets[1],
+					condEndOffset, headerName, path, userInclude, active, isHeuristic, nominationDelegate);
+		}
+		// In a pragma once context store loaded versions of this non-pragma-once include
+		if (pragmaOnceContext && loadedVerisons != null && !loadedVerisons.isEmpty()) {
+			stmt.setLoadedVersions(loadedVerisons.toArray(new ISignificantMacros[loadedVerisons.size()]));
 		}
 	}
 
-	private void processInclusionFromIndex(int offset, String path, InternalFileContent fi) {
+	private void processInclusionFromIndex(int offset, String path, InternalFileContent fi, boolean updateContext) {
 		List<IIndexMacro> mdefs= fi.getMacroDefinitions();
 		for (IIndexMacro macro : mdefs) {
 			addMacroDefinition(macro);
+			if (updateContext)
+				fCurrentContext.internalModification(macro.getNameCharArray());
+		}
+		for (FileVersion version : fi.getNonPragmaOnceVersions()) {
+			fFileContentProvider.addLoadedVersions(version.fPath, Integer.MAX_VALUE, version.fSigMacros);
 		}
 		fLocationMap.skippedFile(fLocationMap.getSequenceNumberForOffset(offset), fi);
 	}
@@ -1346,24 +1509,15 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 		return headerName;
 	}
 	
-	private boolean isCircularInclusion(String filename) {
-		ILocationCtx checkContext= fCurrentContext.getLocationCtx();
-		while (checkContext != null) {
-			if (filename.equals(checkContext.getFilePath())) {
-				return true;
-			}
-			checkContext= checkContext.getParent();
-		}
-		return false;
-	}
-
-
     private void executeDefine(final Lexer lexer, int startOffset, boolean isActive)
     		throws OffsetLimitReachedException {
 		try {
 			ObjectStyleMacro macrodef = fMacroDefinitionParser.parseMacroDefinition(lexer, this);
-			if (isActive)
-				fMacroDictionary.put(macrodef.getNameCharArray(), macrodef);
+			if (isActive) {
+				final char[] macroName = macrodef.getNameCharArray();
+				fMacroDictionary.put(macroName, macrodef);
+				fCurrentContext.internalModification(macroName);
+			}
 			
 			final Token name= fMacroDefinitionParser.getNameToken();
 			fLocationMap.encounterPoundDefine(startOffset, name.getOffset(), name.getEndOffset(),
@@ -1393,6 +1547,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     	PreprocessorMacro definition;
     	if (isActive) {
     		definition= fMacroDictionary.remove(namechars, 0, namechars.length);
+    		fCurrentContext.internalModification(namechars);
     	} else {
     		definition= fMacroDictionary.get(namechars);
     	}
@@ -1422,10 +1577,18 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 	    		handleProblem(IProblem.PREPROCESSOR_DEFINITION_NOT_FOUND, name.getCharImage(), offset, nameEndOffset);
 	    	} else {
 	    		final char[] namechars= name.getCharImage();
+				if (isIfndef) {
+	    			if (IncludeGuardDetection.detectIncludeEndif(lexer)) {
+	    				fExternIncludeGuard= namechars;
+	    			}
+	    		}
 	    		macro= fMacroDictionary.get(namechars);
 	    		isTaken= (macro == null) == isIfndef;
 	    		if (macro == null) {
 	    			macro = new UndefinedMacro(namechars);
+	    			fCurrentContext.significantMacroUndefined(namechars);
+	    		} else {
+	    			fCurrentContext.significantMacroDefined(namechars);
 	    		}
 	    	}
 		}
@@ -1442,7 +1605,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 		return fCurrentContext.setBranchState(conditional, isTaken, withinExpansion, offset);
     }
 
-    private CodeState executeIf(Lexer lexer, int startOffset, boolean isElif,
+	private CodeState executeIf(Lexer lexer, int startOffset, boolean isElif,
     		boolean withinExpansion) throws OffsetLimitReachedException {
 		Conditional cond= fCurrentContext.newBranch(isElif ? BranchKind.eElif : BranchKind.eIf, withinExpansion);
 		if (cond == null) {
@@ -1458,6 +1621,11 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 		int condEndOffset, endOffset;
 
 		if (cond.canHaveActiveBranch(withinExpansion)) {
+			char[] macro= IncludeGuardDetection.detectIfNotDefinedIncludeEndif(lexer);
+			if (macro != null) {
+    			fExternIncludeGuard= macro;
+    		}
+
 			TokenList condition= new TokenList();
 			condEndOffset= getTokensWithinPPDirective(true, condition, withinExpansion);
 			endOffset= lexer.currentToken().getEndOffset();
@@ -1469,6 +1637,14 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 					fExpressionEvaluator.clearMacrosInDefinedExpression();
 					isTaken= fExpressionEvaluator.evaluate(condition, fMacroDictionary, fLocationMap);
 					refs = fExpressionEvaluator.clearMacrosInDefinedExpression();
+					for (IASTName iastName : refs) {
+						IBinding mb= iastName.getBinding();
+						if (mb instanceof UndefinedMacro) {
+							fCurrentContext.significantMacroUndefined(iastName.toCharArray());
+						} else {
+							fCurrentContext.significantMacroDefined(iastName.toCharArray());
+						}
+					}
 				} catch (EvalException e) {
 					handleProblem(e.getProblemID(), e.getProblemArg(), condOffset, endOffset);
 				}
@@ -1531,7 +1707,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     		boolean withinExpansion) throws OffsetLimitReachedException {
     	final ScannerContext scannerCtx= fCurrentContext;
     	scannerCtx.clearInactiveCodeMarkerToken();
-    	int options= STOP_AT_NL;
+    	int options= STOP_AT_NL | REPORT_SIGNIFICANT_MACROS;
     	if (isCondition)
     		options |= PROTECT_DEFINED;
     	
@@ -1545,10 +1721,9 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     		case Lexer.tNEWLINE:
     			break loop;
     		case IToken.tIDENTIFIER:
-    			if (isCondition && CharArrayUtils.equals(Keywords.cDEFINED, t.getCharImage())) {
-    				t.setType(CPreprocessor.tDEFINED);
-    				options |= NO_EXPANSION;	
-    			}
+    			break;
+    		case tDEFINED:
+    			options |= NO_EXPANSION;
     			break;
     		case IToken.tLPAREN:
     			break;
@@ -1639,9 +1814,16 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 	 */
 	private boolean expandMacro(final Token identifier, Lexer lexer, int options,
 			boolean withinExpansion) throws OffsetLimitReachedException {
+		final boolean reportSignificant = (options & REPORT_SIGNIFICANT_MACROS) != 0;
 		final char[] name= identifier.getCharImage();
+		if ((options & PROTECT_DEFINED) != 0 && CharArrayUtils.equals(name, Keywords.cDEFINED)) {
+			identifier.setType(tDEFINED);
+			return false;
+		}
         PreprocessorMacro macro= fMacroDictionary.get(name);
         if (macro == null) {
+        	if (reportSignificant && (options & IGNORE_UNDEFINED_SIGNIFICANT_MACROS) == 0) 
+        		fCurrentContext.significantMacroUndefined(name);
         	return false;
         }
         boolean stopAtNewline= (options & STOP_AT_NL) != 0;
@@ -1653,6 +1835,8 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     			}
     		}
     		if (t.getType() != IToken.tLPAREN) {
+            	if (reportSignificant) 
+            		fCurrentContext.significantMacro(macro);
     			return false;
     		}
         }
@@ -1660,8 +1844,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
         final ITokenSequence input= stopAtNewline ? fLineInputToMacroExpansion : fInputToMacroExpansion;
 		final MacroExpander expander = withinExpansion ? new MacroExpander(this, fMacroDictionary,
 				fLocationMap, fLexOptions) : fMacroExpander;
-        TokenList replacement= expander.expand(input, (options & PROTECT_DEFINED) != 0, macro,
-        		identifier, contentAssist);
+        TokenList replacement= expander.expand(input, options, macro, identifier, contentAssist, fCurrentContext);
     	final IASTName[] expansions= expander.clearImplicitExpansions();
     	final ImageLocationInfo[] ili= expander.clearImageLocationInfos();
     	final Token last= replacement.last();
@@ -1679,5 +1862,5 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 			return fMacroExpander;
 		}
 		return null;
-	}
+	}	
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ExpressionEvaluator.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ExpressionEvaluator.java
index fba757060a2..09ccfce9787 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ExpressionEvaluator.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ExpressionEvaluator.java
@@ -299,11 +299,13 @@ public class ExpressionEvaluator {
     	if (LA() != IToken.tIDENTIFIER) {
     		throw new EvalException(IProblem.SCANNER_ILLEGAL_IDENTIFIER, null);
     	}
-    	PreprocessorMacro macro= fDictionary.get(fTokens.getCharImage());
-    	if (macro != null) {
-    		fMacrosInDefinedExpressions.add(fLocationMap.encounterDefinedExpression(macro, fTokens.getOffset(), fTokens.getEndOffset()));
-    	}
+    	final char[] macroName = fTokens.getCharImage();
+		PreprocessorMacro macro= fDictionary.get(macroName);
     	int result= macro != null ? 1 : 0;
+    	if (macro == null)
+    		macro= new UndefinedMacro(macroName);
+
+    	fMacrosInDefinedExpressions.add(fLocationMap.encounterDefinedExpression(macro, fTokens.getOffset(), fTokens.getEndOffset()));
     	consume();
     	if (parenthesis) {
     		if (LA() != IToken.tRPAREN) {
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ILocationCtx.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ILocationCtx.java
index ac52538bea4..2d9ac67ff07 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ILocationCtx.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ILocationCtx.java
@@ -30,4 +30,8 @@ public interface ILocationCtx {
 	 */
 	ILocationCtx getParent();
 
+	/**
+	 * Returns inclusion statement that created this context, or <code>null</code>.
+	 */
+	ASTInclusionStatement getInclusionStatement();
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ISkippedIndexedFilesListener.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ISkippedIndexedFilesListener.java
index 607e1fd784d..6e913d46d4d 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ISkippedIndexedFilesListener.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ISkippedIndexedFilesListener.java
@@ -28,5 +28,5 @@ public interface ISkippedIndexedFilesListener {
 	/**
 	 * Notifies the listeners that a file is being parsed.
 	 */
-	void replacingFile(InternalFileContentProvider fileContentProvider, InternalFileContent fileContent);
+	void parsingFile(InternalFileContentProvider fileContentProvider, InternalFileContent fileContent);
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/IncludeGuardDetection.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/IncludeGuardDetection.java
new file mode 100644
index 00000000000..2674e80e36a
--- /dev/null
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/IncludeGuardDetection.java
@@ -0,0 +1,165 @@
+/*******************************************************************************
+ * Copyright (c) 2011 Wind River Systems, Inc. and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Markus Schorn - initial API and implementation
+ *******************************************************************************/ 
+
+package org.eclipse.cdt.internal.core.parser.scanner;
+
+import static org.eclipse.cdt.core.parser.OffsetLimitReachedException.ORIGIN_PREPROCESSOR_DIRECTIVE;
+
+import org.eclipse.cdt.core.parser.IPreprocessorDirective;
+import org.eclipse.cdt.core.parser.IToken;
+import org.eclipse.cdt.core.parser.Keywords;
+import org.eclipse.cdt.core.parser.OffsetLimitReachedException;
+import org.eclipse.cdt.core.parser.util.CharArrayIntMap;
+import org.eclipse.cdt.core.parser.util.CharArrayUtils;
+
+/**
+ * Helper class for detecting include guards 
+ */
+public class IncludeGuardDetection {
+	public static char[] detectIncludeGuard(AbstractCharArray content, Lexer.LexerOptions lexOptions, CharArrayIntMap ppKeywords) {
+		Lexer l= new Lexer(content, lexOptions, ILexerLog.NULL, null);
+		char[] guard= findIncludeGuard(l, ppKeywords);
+		if (guard != null && currentIfSpansFile(l, ppKeywords)) {
+			return guard;
+		}
+		return null;
+	}
+
+	private static char[] findIncludeGuard(Lexer l, CharArrayIntMap ppKeywords) {
+ 		try {
+  			if (skipAll(l, Lexer.tNEWLINE).getType() == IToken.tPOUND) { 
+				Token t = l.nextToken();
+				if (t.getType() == IToken.tIDENTIFIER) {
+					char[] guard= null;
+					switch(ppKeywords.get(t.getCharImage())) {
+					case IPreprocessorDirective.ppIfndef:
+						// #ifndef GUARD
+						t= l.nextToken();
+						if (t.getType() == IToken.tIDENTIFIER) {
+							guard= t.getCharImage();
+						}
+						break;
+					case IPreprocessorDirective.ppIf:
+						// #if !defined GUARD
+						// #if ((!((defined (GUARD)))))
+						guard = findNotDefined(l); 
+						break;
+					}
+					if (guard != null) {
+						// #define GUARD
+						l.consumeLine(ORIGIN_PREPROCESSOR_DIRECTIVE);
+						if (skipAll(l, Lexer.tNEWLINE).getType() == IToken.tPOUND
+								&& checkToken(l.nextToken(), Keywords.cDEFINE)
+								&& checkToken(l.nextToken(), guard)) {
+							l.consumeLine(ORIGIN_PREPROCESSOR_DIRECTIVE);
+							return guard;
+						}
+					}
+				}
+  			}
+ 		} catch (OffsetLimitReachedException e) {
+ 		}
+ 		return null;
+ 	}
+
+	private static char[] findNotDefined(Lexer l) throws OffsetLimitReachedException {
+		Token t;
+		if (skipAll(l, IToken.tLPAREN).getType() == IToken.tNOT
+				&& checkToken(skipAll(l, IToken.tLPAREN), Keywords.cDEFINED)) {
+			t= l.nextToken(); // only a single parenthesis is allowed
+			if (t.getType() == IToken.tLPAREN)
+				t= l.nextToken();
+			if (t.getType() == IToken.tIDENTIFIER) {
+				char[] guard= t.getCharImage();
+				if (skipAll(l, IToken.tRPAREN).getType() == Lexer.tNEWLINE)
+					return guard;
+			}
+		}
+		return null;
+	}
+
+	private static boolean checkToken(Token t, char[] image) throws OffsetLimitReachedException {
+		return CharArrayUtils.equals(t.getCharImage(), image);
+	}
+	
+	private static boolean currentIfSpansFile(Lexer l, CharArrayIntMap ppKeywords) {
+		// Check if the #ifndef spans the entire file
+		try {
+			int nesting= 1;
+			while (nesting > 0) {
+				Token t= l.nextDirective();
+				if (t.getType() == IToken.tEND_OF_INPUT)
+					return true;
+				switch(ppKeywords.get(l.nextToken().getCharImage())) {
+				case IPreprocessorDirective.ppIf:
+				case IPreprocessorDirective.ppIfdef:
+				case IPreprocessorDirective.ppIfndef:
+					nesting++;
+					break;
+				case IPreprocessorDirective.ppEndif:
+					nesting--;
+					break;
+				}
+			}
+			l.consumeLine(ORIGIN_PREPROCESSOR_DIRECTIVE);
+			return skipAll(l, Lexer.tNEWLINE).getType() == IToken.tEND_OF_INPUT;
+		} catch (OffsetLimitReachedException e) {
+		}
+		return true;
+	}
+	
+	private static Token skipAll(Lexer l, int kind) throws OffsetLimitReachedException {
+		// Skip empty lines
+		Token t= l.nextToken();
+		while (t.getType() == kind)
+			t= l.nextToken();
+		return t;
+	}
+
+	
+	public static boolean detectIncludeEndif(Lexer l) {
+		l.saveState();
+		try {
+			return findIncludeEndif(l);
+		} catch (OffsetLimitReachedException e) {
+		} finally {
+			l.restoreState();
+		}
+		return false;
+	}
+
+	private static boolean findIncludeEndif(Lexer l) throws OffsetLimitReachedException {
+		if (skipAll(l, Lexer.tNEWLINE).getType() != IToken.tPOUND)
+			return false;
+		if (!checkToken(l.nextToken(), Keywords.cINCLUDE))
+			return false;
+		l.consumeLine(ORIGIN_PREPROCESSOR_DIRECTIVE);
+		if (skipAll(l, Lexer.tNEWLINE).getType() != IToken.tPOUND)
+			return false;
+		if (!checkToken(l.nextToken(), Keywords.cENDIF))
+			return false;
+		
+		return true;
+	}
+
+	public static char[] detectIfNotDefinedIncludeEndif(Lexer l) {
+		l.saveState();
+		try {
+			char[] guard= findNotDefined(l);
+			if (guard != null && findIncludeEndif(l))
+				return guard;
+		} catch (OffsetLimitReachedException e) {
+		} finally {
+			l.restoreState();
+		}
+		return null;
+	}
+}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/InternalFileContent.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/InternalFileContent.java
index ccfacf5ece7..56534886481 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/InternalFileContent.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/InternalFileContent.java
@@ -17,6 +17,7 @@ import org.eclipse.cdt.core.dom.ast.cpp.ICPPUsingDirective;
 import org.eclipse.cdt.core.index.IIndexFile;
 import org.eclipse.cdt.core.index.IIndexMacro;
 import org.eclipse.cdt.core.parser.FileContent;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 
 /**
  * Instructs the preprocessor on how to handle a file-inclusion.
@@ -38,11 +39,21 @@ public class InternalFileContent extends FileContent {
 		USE_SOURCE
 	}
 
+	public static class FileVersion {
+		public final String fPath;
+		public final ISignificantMacros fSigMacros;
+		public FileVersion(String path, ISignificantMacros sig) {
+			fPath= path;
+			fSigMacros= sig;
+		}
+	}
+	
 	private final InclusionKind fKind;
 	private final AbstractCharArray fSource;
 	private final List<IIndexMacro> fMacroDefinitions;
 	private final List<ICPPUsingDirective> fUsingDirectives;
 	private final String fFileLocation;
+	private final List<FileVersion> fNonPragmaOnceFiles;
 	private boolean fHeuristic;
 	private boolean fIsSource= false;
 	private List<IIndexFile> fFiles;
@@ -64,6 +75,7 @@ public class InternalFileContent extends FileContent {
 		fMacroDefinitions= null;
 		fUsingDirectives= null;
 		fSource= null;
+		fNonPragmaOnceFiles= null;
 	}
 
 	/**
@@ -79,6 +91,7 @@ public class InternalFileContent extends FileContent {
 		fSource= content;
 		fMacroDefinitions= null;
 		fUsingDirectives= null;
+		fNonPragmaOnceFiles= null;
 		if (fFileLocation == null) {
 			throw new IllegalArgumentException();
 		}
@@ -92,13 +105,14 @@ public class InternalFileContent extends FileContent {
 	 * @throws IllegalArgumentException in case the fileLocation or the macroDefinitions are <code>null</code>.
 	 */
 	public InternalFileContent(String fileLocation, List<IIndexMacro> macroDefinitions, List<ICPPUsingDirective> usingDirectives,
-			List<IIndexFile> files) {
+			List<IIndexFile> files, List<FileVersion> nonPragmaOnceVersions) {
 		fKind= InclusionKind.FOUND_IN_INDEX;
 		fFileLocation= fileLocation;
 		fSource= null;
 		fUsingDirectives= usingDirectives;
 		fMacroDefinitions= macroDefinitions;
 		fFiles= files;
+		fNonPragmaOnceFiles= nonPragmaOnceVersions;
 	}
 
 	/**
@@ -155,6 +169,10 @@ public class InternalFileContent extends FileContent {
 	public List<IIndexFile> getFilesIncluded() {
 		return fFiles;
 	}
+	
+	public List<FileVersion> getNonPragmaOnceVersions() {
+		return fNonPragmaOnceFiles;
+	}
 
 	/**
 	 * Returns whether this inclusion was found by a heuristics.
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/InternalFileContentProvider.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/InternalFileContentProvider.java
index 17c9e046bd3..82668c6293b 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/InternalFileContentProvider.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/InternalFileContentProvider.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2009 Wind River Systems, Inc. and others.
+ * Copyright (c) 2009, 2011 Wind River Systems, Inc. and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -7,14 +7,25 @@
  *
  * Contributors:
  *     Markus Schorn - initial API and implementation
+ *     Sergey Prigogin (Google)
  *******************************************************************************/ 
 package org.eclipse.cdt.internal.core.parser.scanner;
 
 import java.io.File;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 
+import org.eclipse.cdt.core.dom.ast.IASTPreprocessorIncludeStatement;
+import org.eclipse.cdt.core.dom.ast.IFileNomination;
+import org.eclipse.cdt.core.index.IIndexFile;
 import org.eclipse.cdt.core.index.IIndexFileLocation;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.core.parser.IncludeFileContentProvider;
 import org.eclipse.cdt.internal.core.dom.IIncludeFileResolutionHeuristics;
+import org.eclipse.cdt.internal.core.parser.IMacroDictionary;
 import org.eclipse.cdt.internal.core.parser.scanner.InternalFileContent.InclusionKind;
 
 /**
@@ -22,20 +33,25 @@ import org.eclipse.cdt.internal.core.parser.scanner.InternalFileContent.Inclusio
  */
 public abstract class InternalFileContentProvider extends IncludeFileContentProvider {
 	private IIncludeFileResolutionHeuristics fIncludeResolutionHeuristics;
+    private final Map<String, IFileNomination> fPragmaOnce= new HashMap<String, IFileNomination>();
+    private final Map<String, List<ISignificantMacros>> fLoadedVersions= new HashMap<String, List<ISignificantMacros>>();
 
 	/**
-	 * Check whether the specified inclusion exists.
+	 * Checks whether the specified inclusion exists.
 	 */
 	public boolean getInclusionExists(String path) {
 		return new File(path).exists();
 	}
 
 	/**
-	 * Create an InclusionContent object for the given location.
-     * return an inclusion content or <code>null</code> if the location does not exist.
+	 * Creates an InclusionContent object for the given location.
+	 * @param filePath the absolute location of the file.
+	 * @param macroDictionary macros defined at the inclusion point.
+     * @return Returns an inclusion content, or <code>null</code> if the location does not exist.
 	 * @see InternalFileContent
 	 */
-	public abstract InternalFileContent getContentForInclusion(String path);
+	public abstract InternalFileContent getContentForInclusion(String filePath,
+			IMacroDictionary macroDictionary);
 
 	/** 
 	 * Called only when used as a delegate of the index file content provider.
@@ -46,28 +62,38 @@ public abstract class InternalFileContentProvider extends IncludeFileContentProv
 	 * Returns a file-content object of kind {@link InclusionKind#FOUND_IN_INDEX}, representing
 	 * the content from the context of the given file up to where the file actually gets included,
 	 * or <code>null</code> if this cannot be done.
+	 * @param filePath the absolute location of the file.
+	 * @param macroDictionary macros defined at the inclusion point.
 	 */
-	public InternalFileContent getContentForContextToHeaderGap(String location) {
+	public InternalFileContent getContentForContextToHeaderGap(String filePath,
+			IMacroDictionary macroDictionary) {
 		return null;
 	}
 
-	/**
-	 * Reports the path of the translation unit, such that it is known as included.
+	public void resetForTranslationUnit() {
+		fPragmaOnce.clear();
+		fLoadedVersions.clear();
+	}
+
+	/** 
+	 * Reports detection of pragma once semantics.
 	 */
-	public void reportTranslationUnitFile(String filePath) {
+	public void reportPragmaOnceSemantics(String file, IFileNomination nomination) {
+		fPragmaOnce.put(file, nomination);
 	}
-	
+
 	/**
-	 * Returns whether or not the file has been included, or <code>null</code> if the content provider
-	 * does not track that.
+	 * Returns {@link IASTPreprocessorIncludeStatement} or {@link IIndexFile}, in
+	 * case the file has been included using pragma once semantics,
+	 * or <code>null</code> otherwise.
 	 */
-	public Boolean hasFileBeenIncludedInCurrentTranslationUnit(String location) {
-		return null;
+	public IFileNomination isIncludedWithPragmaOnceSemantics(String filePath) {
+		return fPragmaOnce.get(filePath);
 	}
 
 	/**
-	 * Returns a strategy for heuristically resolving includes, or <code>null</code> if this shall not
-	 * be done.
+	 * Returns a strategy for heuristically resolving includes, or <code>null</code> if this shall
+	 * not be done.
 	 */
 	public final IIncludeFileResolutionHeuristics getIncludeHeuristics() {
 		return fIncludeResolutionHeuristics;
@@ -76,4 +102,26 @@ public abstract class InternalFileContentProvider extends IncludeFileContentProv
 	public final void setIncludeResolutionHeuristics(IIncludeFileResolutionHeuristics heuristics) {
 		fIncludeResolutionHeuristics= heuristics;
 	}
+
+	public List<ISignificantMacros> getLoadedVersions(String path) {
+		List<ISignificantMacros> result = fLoadedVersions.get(path);
+		return result == null ? Collections.<ISignificantMacros>emptyList() : result;
+	}
+
+	public void addLoadedVersions(String path, int reduceVersions, ISignificantMacros sig) {
+		List<ISignificantMacros> list= fLoadedVersions.get(path);
+		if (list == null || reduceVersions == 0) {
+			fLoadedVersions.put(path, Collections.singletonList(sig));
+		} else if (!list.contains(sig)) {
+			if (list.size() == 1) {
+				ISignificantMacros first = list.get(0);
+				list= new ArrayList<ISignificantMacros>(2);
+				list.add(first);
+				fLoadedVersions.put(path, list);
+			} else if (reduceVersions > 0 && reduceVersions < list.size()) {
+				list.subList(reduceVersions, list.size()).clear();
+			}
+			list.add(sig);
+		}
+	}		
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/Lexer.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/Lexer.java
index 2bf70b1e2f8..441c2907d1b 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/Lexer.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/Lexer.java
@@ -85,10 +85,14 @@ final public class Lexer implements ITokenSequence {
 	private Token fToken;
 	private Token fLastToken;
 	
-	// for the few cases where we have to lookahead more than one character
+	// For the few cases where we have to lookahead more than one character
 	private int fMarkOffset;
 	private int fMarkEndOffset;
 	private int fMarkPrefetchedChar;
+	// To store the entire state.
+	private boolean fMarkInsideIncludeDirective;
+	private Token fMarkToken;
+	private Token fMarkLastToken;
 	
 	public Lexer(char[] input, LexerOptions options, ILexerLog log, Object source) {
 		this(new CharArray(input), 0, input.length, options, log, source);
@@ -1256,4 +1260,22 @@ final public class Lexer implements ITokenSequence {
 		restorePhase3();
 		return result;
 	}
+
+	public void saveState() {
+		fMarkOffset= fOffset;
+		fMarkEndOffset= fEndOffset;
+		fMarkPrefetchedChar= fCharPhase3;
+		fMarkInsideIncludeDirective= fInsideIncludeDirective;
+		fMarkToken= fToken;
+		fMarkLastToken= fLastToken;
+	}
+
+	public void restoreState() {
+		fOffset= fMarkOffset;
+		fEndOffset= fMarkEndOffset;
+		fCharPhase3= fMarkPrefetchedChar;
+		fInsideIncludeDirective= fMarkInsideIncludeDirective;
+		fToken= fMarkToken;
+		fLastToken= fMarkLastToken;
+	}
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationCtxContainer.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationCtxContainer.java
index 61e76bf99b5..bd4e98ad844 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationCtxContainer.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationCtxContainer.java
@@ -259,4 +259,9 @@ class LocationCtxContainer extends LocationCtx {
 		}
 		return result;
 	}
+	
+	@Override
+	public String toString() {
+		return "<synthetic>"; //$NON-NLS-1$
+	}
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationCtxFile.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationCtxFile.java
index 8964b2bf755..a33b6195dbc 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationCtxFile.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationCtxFile.java
@@ -131,4 +131,9 @@ class LocationCtxFile extends LocationCtxContainer {
 	public boolean isSourceFile() {
 		return fIsSource;
 	}
+	
+	@Override
+	public String toString() {
+		return fFilename;
+	}
 }
\ No newline at end of file
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationCtxMacroExpansion.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationCtxMacroExpansion.java
index ed92105bffc..9e37e56a97f 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationCtxMacroExpansion.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationCtxMacroExpansion.java
@@ -105,4 +105,9 @@ class LocationCtxMacroExpansion extends LocationCtx {
 	public ASTPreprocessorName[] getNestedMacroReferences() {
 		return fLocationMap.getNestedMacroReferences((ASTMacroExpansion) fExpansionName.getParent());
 	}
+	
+	@Override
+	public String toString() {
+		return "Expansion of " + fExpansionName.toString(); //$NON-NLS-1$
+	}
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationMap.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationMap.java
index 23141ad545e..1e849f2b4f5 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationMap.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/LocationMap.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2007, 2010 Wind River Systems, Inc. and others.
+ * Copyright (c) 2007, 2011 Wind River Systems, Inc. and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -30,8 +30,12 @@ import org.eclipse.cdt.core.dom.ast.IASTProblem;
 import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit;
 import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit.IDependencyTree;
 import org.eclipse.cdt.core.dom.ast.IBinding;
+import org.eclipse.cdt.core.dom.ast.IFileNomination;
 import org.eclipse.cdt.core.dom.ast.IMacroBinding;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
+import org.eclipse.cdt.core.parser.util.CharArrayObjectMap;
 import org.eclipse.cdt.core.parser.util.CharArrayUtils;
+import org.eclipse.cdt.internal.core.dom.parser.ASTNode;
 import org.eclipse.cdt.internal.core.dom.parser.ASTNodeSpecification;
 import org.eclipse.cdt.internal.core.dom.parser.ASTProblem;
 import org.eclipse.cdt.internal.core.parser.scanner.Lexer.LexerOptions;
@@ -130,7 +134,7 @@ public class LocationMap implements ILocationResolver {
 		int nameEndNumber= getSequenceNumberForOffset(nameEndOffset);
 		int endNumber= getSequenceNumberForOffset(endOffset);
 		final ASTInclusionStatement inclusionStatement= 
-			new ASTInclusionStatement(fTranslationUnit, startNumber, nameNumber, nameEndNumber, endNumber, name, filename, userInclude, true, heuristic);
+			new ASTInclusionStatement(fTranslationUnit, startNumber, nameNumber, nameEndNumber, endNumber, name, filename, userInclude, true, heuristic, null);
 		fDirectives.add(inclusionStatement);
 		fCurrentContext= new LocationCtxFile((LocationCtxContainer) fCurrentContext, filename, buffer, startOffset, endOffset, endNumber, inclusionStatement, isSource);
 		fLastChildInsertionOffset= 0;
@@ -226,14 +230,17 @@ public class LocationMap implements ILocationResolver {
 	 * @param userInclude <code>true</code> when specified with double-quotes.
 	 * @param active <code>true</code> when include appears in active code.
 	 */
-	public void encounterPoundInclude(int startOffset, int nameOffset, int nameEndOffset, int endOffset,
-			char[] name, String filename, boolean userInclude, boolean active, boolean heuristic) {
+	public ASTInclusionStatement encounterPoundInclude(int startOffset, int nameOffset, int nameEndOffset, int endOffset,
+			char[] name, String filename, boolean userInclude, boolean active, boolean heuristic,
+			IFileNomination nominationDelegate) {
 		startOffset= getSequenceNumberForOffset(startOffset);	
 		nameOffset= getSequenceNumberForOffset(nameOffset);		
 		nameEndOffset= getSequenceNumberForOffset(nameEndOffset);
 		endOffset= getSequenceNumberForOffset(endOffset);
-		fDirectives.add(new ASTInclusionStatement(fTranslationUnit, startOffset, nameOffset,
-				nameEndOffset, endOffset, name, filename, userInclude, active, heuristic));
+		final ASTInclusionStatement inc = new ASTInclusionStatement(fTranslationUnit, startOffset, nameOffset,
+				nameEndOffset, endOffset, name, filename, userInclude, active, heuristic, nominationDelegate);
+		fDirectives.add(inc);
+		return inc;
 	}
 
 	public void encounteredComment(int offset, int endOffset, boolean isBlockComment) {
@@ -743,10 +750,39 @@ public class LocationMap implements ILocationResolver {
 		}
 	}
 	
-	public void replacingFile(InternalFileContentProvider fileContentProvider, 
+	public void parsingFile(InternalFileContentProvider fileContentProvider, 
 			InternalFileContent fileContent) {
 		for (ISkippedIndexedFilesListener l : fSkippedFilesListeners) {
-			l.replacingFile(fileContentProvider, fileContent);
+			l.parsingFile(fileContentProvider, fileContent);
 		}
-	}		
+	}
+
+	public IFileNomination reportPragmaOnceSemantics(ILocationCtx locationCtx) {
+		if (locationCtx == fRootContext) {
+			if (fTranslationUnit != null) {
+				fTranslationUnit.setPragmaOnceSemantics(true);
+			}
+			return fTranslationUnit;
+		} else if (locationCtx instanceof LocationCtxFile) {
+			ASTInclusionStatement stmt = ((LocationCtxFile) locationCtx).getInclusionStatement();
+			if (stmt != null) {
+				stmt.setPragamOnceSemantics(true);
+			}
+			return stmt;
+		}
+		return null;
+	}
+
+	public void endTranslationUnit(int endOffset, CharArrayObjectMap<char[]> sigMacros) {
+		if (fTranslationUnit != null) {
+			int offset= getSequenceNumberForOffset(endOffset);
+			((ASTNode) fTranslationUnit).setLength(offset);
+
+			if (sigMacros != null) {
+				ISignificantMacros sig = sigMacros.isEmpty() ? ISignificantMacros.NONE 
+						: new SignificantMacros(sigMacros);
+				fTranslationUnit.setSignificantMacros(sig);
+			}
+		}
+	}
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/MacroExpander.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/MacroExpander.java
index b3a05055682..9667a1ea3cc 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/MacroExpander.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/MacroExpander.java
@@ -136,6 +136,8 @@ public class MacroExpander {
 	private String fFixedCurrentFilename;
 	private int fFixedLineNumber;
 	private char[] fFixedInput;
+	private ScannerContext fReportMacros;
+	private boolean fReportUndefined;
 	
 	public MacroExpander(ILexerLog log, CharArrayMap<PreprocessorMacro> macroDictionary, LocationMap locationMap, LexerOptions lexOptions) {
 		fDictionary= macroDictionary;
@@ -147,8 +149,19 @@ public class MacroExpander {
 	
 	/** 
 	 * Expects that the identifier has been consumed, stores the result in the list provided.
+	 * @param scannerContext 
 	 */
-	public TokenList expand(ITokenSequence lexer, final boolean isPPCondition, PreprocessorMacro macro, Token identifier, boolean completionMode) throws OffsetLimitReachedException {
+	public TokenList expand(ITokenSequence lexer, final int ppOptions,
+			PreprocessorMacro macro, Token identifier, boolean completionMode,
+			ScannerContext scannerContext) throws OffsetLimitReachedException {
+		final boolean protectDefined= (ppOptions & CPreprocessor.PROTECT_DEFINED) != 0;
+		if ((ppOptions & CPreprocessor.REPORT_SIGNIFICANT_MACROS) != 0) {
+			fReportMacros= scannerContext;
+			fReportUndefined= (ppOptions & CPreprocessor.IGNORE_UNDEFINED_SIGNIFICANT_MACROS) == 0;
+		} else {
+			fReportMacros= null;
+		}
+		
 		fImplicitMacroExpansions.clear();
 		fImageLocationInfos.clear();
 		
@@ -170,7 +183,7 @@ public class MacroExpander {
 
 			input.prepend(firstExpansion);
 
-			result= expandAll(input, forbidden, isPPCondition, null);
+			result= expandAll(input, forbidden, protectDefined, null);
 		} catch (CompletionInMacroExpansionException e) {
 			// for content assist in macro expansions, we return the list of tokens of the 
 			// parameter at the current cursor position and hope that they make sense if 
@@ -180,6 +193,7 @@ public class MacroExpander {
 			result= e.getParameterTokens().cloneTokens();
 		}
 		postProcessTokens(result);
+		fReportMacros= null;
 		return result;
 	}
 
@@ -193,6 +207,7 @@ public class MacroExpander {
 		fFixedInput= beforeExpansion.toCharArray();
 		fFixedCurrentFilename= filePath;
 		fFixedLineNumber= lineNumber;
+		fReportMacros= null;
 		Lexer lexer= new Lexer(fFixedInput, fLexOptions, fLog, this);
 		
 		try {
@@ -240,6 +255,9 @@ public class MacroExpander {
 			IdentityHashMap<PreprocessorMacro, PreprocessorMacro> forbidden, TokenSource input, TokenList result,
 			MacroExpansionTracker tracker) 
 			throws OffsetLimitReachedException {
+		if (fReportMacros != null)
+			fReportMacros.significantMacro(macro);
+		
 		if (macro.isFunctionStyle()) {
 			final int paramCount = macro.getParameterPlaceholderList().length;
 			final TokenSource[] argInputs= new TokenSource[paramCount];
@@ -351,6 +369,13 @@ public class MacroExpander {
 					protect= true;
 				} else if (macro == null || (macro.isFunctionStyle() && !input.findLParenthesis())) {
 					// Tricky: Don't mark function-style macros if you don't find the left parenthesis
+					if (fReportMacros != null) {
+						if (macro != null) {
+							fReportMacros.significantMacro(macro);
+						} else if (fReportUndefined){
+							fReportMacros.significantMacroUndefined(image);
+						}
+					}
 					result.append(t);
 				} else if (forbidden.containsKey(macro)) {
 					t.setType(CPreprocessor.tEXPANDED_IDENTIFIER); // prevent any further expansion
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/MultiMacroExpansionExplorer.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/MultiMacroExpansionExplorer.java
index a307d673c4b..89deea45e9e 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/MultiMacroExpansionExplorer.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/MultiMacroExpansionExplorer.java
@@ -22,6 +22,7 @@ import org.eclipse.cdt.core.dom.ast.IASTNode;
 import org.eclipse.cdt.core.dom.ast.IASTNodeSelector;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorElifStatement;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorIfStatement;
+import org.eclipse.cdt.core.dom.ast.IASTPreprocessorIncludeStatement;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorMacroDefinition;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorMacroExpansion;
 import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit;
@@ -48,13 +49,14 @@ public class MultiMacroExpansionExplorer extends MacroExpansionExplorer {
 			fOffset= offset;
 			fLength= length;
 		}
-		public int getNodeOffset() {return fOffset;}
-		public int getNodeLength() {return fLength;}
-		public String getFileName() {return fFilePath;}
-
-		public int getStartingLineNumber() {return 0;}
-		public int getEndingLineNumber() {return 0;}
-		public IASTFileLocation asFileLocation() {return this;}
+		public int getNodeOffset() { return fOffset; }
+		public int getNodeLength() { return fLength; }
+		public String getFileName() { return fFilePath; }
+
+		public int getStartingLineNumber() { return 0; }
+		public int getEndingLineNumber() { return 0; }
+		public IASTFileLocation asFileLocation() { return this; }
+		public IASTPreprocessorIncludeStatement getContextInclusionStatement() { return null; }
 	}
 
 	private final char[] fSource;
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ScannerContext.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ScannerContext.java
index b032956b7d8..256fb07825e 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ScannerContext.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/ScannerContext.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2007, 2009 Wind River Systems, Inc. and others.
+ * Copyright (c) 2007, 2011 Wind River Systems, Inc. and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -12,8 +12,12 @@ package org.eclipse.cdt.internal.core.parser.scanner;
 
 import java.util.ArrayList;
 
+import org.eclipse.cdt.core.dom.ast.IMacroBinding;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.core.parser.IToken;
 import org.eclipse.cdt.core.parser.OffsetLimitReachedException;
+import org.eclipse.cdt.core.parser.util.CharArrayObjectMap;
+import org.eclipse.cdt.core.parser.util.CharArraySet;
 
 /**
  * Represents part of the input to the preprocessor. This may be a file or the result of a macro expansion.
@@ -43,6 +47,7 @@ final class ScannerContext {
 	}
 	
 	private CodeState fInactiveState= CodeState.eSkipInactive;
+	private final int fDepth;
 	private final ILocationCtx fLocationCtx;
 	private final ScannerContext fParent;
 	private final Lexer fLexer;
@@ -51,6 +56,11 @@ final class ScannerContext {
 	private CodeState fCurrentState= CodeState.eActive;
 	private IncludeSearchPathElement fFoundOnPath;
 	private String fFoundViaDirective;
+	private CharArraySet fInternalModifications;
+	private CharArrayObjectMap<char[]> fSignificantMacros;
+	private boolean fPragmaOnce;
+	private int fLoadedVersionCount;
+	
 
 	/**
 	 * @param ctx 
@@ -60,6 +70,7 @@ final class ScannerContext {
 		fLocationCtx= ctx;
 		fParent= parent;
 		fLexer= lexer;
+		fDepth = parent == null ? 0 : parent.fDepth+1;
 	}
 	
 	public ScannerContext(ILocationCtx ctx, ScannerContext parent, TokenList tokens) {
@@ -88,6 +99,13 @@ final class ScannerContext {
 	}
 
 	/**
+	 * Returns the depth of this context, equals the number of parents of this context.
+	 */
+	public final int getDepth() {
+		return fDepth;
+	}
+	
+	/**
 	 * Returns the lexer for this context.
 	 */
 	public final Lexer getLexer() {
@@ -297,4 +315,123 @@ final class ScannerContext {
 		fFoundOnPath= foundOnPath;
 		fFoundViaDirective= viaDirective;
 	}
+	
+	public void trackSignificantMacros() {
+		fInternalModifications= new CharArraySet(5);
+		fSignificantMacros= new CharArrayObjectMap<char[]>(5);
+	}
+	
+	public void setPragmaOnce(boolean val) {
+		fPragmaOnce= val;
+	}
+	
+	public boolean isPragmaOnce() {
+		return fPragmaOnce;
+	}
+
+	public void internalModification(char[] macroName) {
+		if (fInternalModifications != null)
+			fInternalModifications.put(macroName);
+	}
+	
+	public void significantMacro(IMacroBinding macro) {
+		final char[] macroName= macro.getNameCharArray();
+		if (fInternalModifications != null && !fInternalModifications.containsKey(macroName)) {
+			fSignificantMacros.put(macroName, macro.getExpansion());
+		}
+	}
+	
+	public void significantMacroDefined(char[] macroName) {
+		if (fInternalModifications != null && !fInternalModifications.containsKey(macroName)) {
+			addSignificantMacroDefined(macroName);
+		}
+	}
+
+	private void addSignificantMacroDefined(char[] macroName) {
+		char[] old= fSignificantMacros.put(macroName, SignificantMacros.DEFINED);
+		if (old != null && old != SignificantMacros.DEFINED) {
+			// Put back more detailed condition
+			fSignificantMacros.put(macroName, old);
+		}
+	}
+	
+	public void significantMacroUndefined(char[] macroName) {
+		if (fInternalModifications != null && !fInternalModifications.containsKey(macroName)) {
+			fSignificantMacros.put(macroName, SignificantMacros.UNDEFINED);
+		}
+	}
+	
+	public CharArrayObjectMap<char[]> getSignificantMacros() {
+		return fSignificantMacros;
+	}
+
+	public void propagateSignificantMacros() {
+		if (fInternalModifications == null)
+			return;
+		
+		if (fParent != null) {
+			final CharArraySet local = fParent.fInternalModifications;
+			if (local != null) {
+				final CharArrayObjectMap<char[]> significant = fParent.fSignificantMacros;
+				for (int i=0; i<fSignificantMacros.size(); i++) {
+					final char[] name = fSignificantMacros.keyAt(i);
+					if (!local.containsKey(name)) {
+						final char[] value= fSignificantMacros.getAt(i);
+						if (value == SignificantMacros.DEFINED) {
+							if (!local.containsKey(name)) {
+								fParent.addSignificantMacroDefined(name);
+							}
+						} else {
+							significant.put(name, value);
+						}
+					}
+				}
+				local.addAll(fInternalModifications);
+			}
+		}
+		fInternalModifications= null;
+		fSignificantMacros= null;
+	}
+
+	public void addSignificantMacros(ISignificantMacros sm) {
+		if (fInternalModifications == null)
+			return;
+		
+		sm.accept(new ISignificantMacros.IVisitor() {
+			public boolean visitValue(char[] macro, char[] value) {
+				if (!fInternalModifications.containsKey(macro)) {
+					fSignificantMacros.put(macro, value);
+				}
+				return true;
+			}
+			public boolean visitUndefined(char[] macro) {
+				if (!fInternalModifications.containsKey(macro)) {
+					fSignificantMacros.put(macro, SignificantMacros.UNDEFINED);
+				}
+				return true;
+			}
+			public boolean visitDefined(char[] macro) {
+				if (!fInternalModifications.containsKey(macro)) {
+					fSignificantMacros.put(macro, SignificantMacros.DEFINED);
+				}
+				return true;
+			}
+		});
+	}
+
+	public int getLoadedVersionCount() {
+		return fLoadedVersionCount;
+	}
+
+	public void setLoadedVersionCount(int count) {
+		fLoadedVersionCount= count;
+	}
+	
+	@Override
+	public String toString() {
+		if (fParent == null)
+			return fLocationCtx.toString();
+		
+		return fParent.toString() + "\n" + fLocationCtx.toString(); //$NON-NLS-1$
+	}
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/SignificantMacros.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/SignificantMacros.java
new file mode 100644
index 00000000000..a997540fd5b
--- /dev/null
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/SignificantMacros.java
@@ -0,0 +1,169 @@
+/*******************************************************************************
+ * Copyright (c) 2011 Google, Inc and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ * 	   Sergey Prigogin (Google) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.internal.core.parser.scanner;
+
+import java.util.Arrays;
+import java.util.Comparator;
+
+import org.eclipse.cdt.core.parser.ISignificantMacros;
+import org.eclipse.cdt.core.parser.util.CharArrayObjectMap;
+import org.eclipse.cdt.core.parser.util.CharArrayUtils;
+
+/**
+ * A set of static methods to encode Map<String, String> as an array of characters and to decode
+ * it back.
+ *
+ * The map is encoded as:
+ * <code>&lt;number_of_entries&gt;,&lt;key1&gt;&lt;value1&gt;...&lt;keyN&gt;&lt;valueN&gt;</code>.
+ * <p>
+ * Each string is encoded as: <code>&lt;number_of_characters&gt;,&lt;characters&gt;</code>.
+ * A <code>null</code> string is encoded as a single comma.
+ */
+public class SignificantMacros implements ISignificantMacros {
+	public static final char[] UNDEFINED = {}; 
+	public static final char[] DEFINED = {};
+	private static final int ENCODED_UNDEFINED = Character.MAX_VALUE;
+	private static final int ENCODED_DEFINED = Character.MAX_VALUE-1;
+	private static final Comparator<Object> SORTER = new Comparator<Object>() {
+		public int compare(Object o1, Object o2) {
+			return CharArrayUtils.compare((char[])o1, (char[])o2);
+		}
+	}; 
+			
+	private final char[] fEncoded;
+	private int fHash;
+
+	public SignificantMacros(char[] encoded) {
+		assert encoded != null;
+		fEncoded= encoded;
+	}
+
+	public SignificantMacros(CharArrayObjectMap<char[]> sigMacros) {
+		fEncoded= encode(sigMacros);
+	}
+
+	private char[] encode(CharArrayObjectMap<char[]> sigMacros) {
+		StringBuilder buffer= new StringBuilder();
+		Object[] keys= sigMacros.keyArray();
+		Arrays.sort(keys, SORTER);
+		for (Object key : keys) {
+			char[] name= (char[]) key;
+			char[] value= sigMacros.get(name);
+			buffer.append((char) name.length).append(name);
+			if (value == DEFINED) {
+				buffer.append((char) ENCODED_DEFINED);
+			} else if (value == UNDEFINED) {
+				buffer.append((char) ENCODED_UNDEFINED);
+			} else {
+				buffer.append((char) value.length).append(value);
+			}
+		}
+		int len= buffer.length();
+		char[] result= new char[len];
+		buffer.getChars(0, len, result, 0);
+		return result;
+	}
+
+	@Override
+	public int hashCode() {
+		int h = fHash;
+		if (h == 0) {
+		    char val[] = fEncoded;
+		    int len = fEncoded.length;
+		    for (int i = 0; i < len; i++) {
+		    	h = 31*h + val[i];
+		    }
+		    fHash = h;
+		}
+		return h;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		return obj instanceof SignificantMacros 
+				&& hashCode() == obj.hashCode() 
+				&& CharArrayUtils.equals(fEncoded, ((SignificantMacros) obj).fEncoded);
+	}
+
+	public boolean accept(IVisitor visitor) {
+		final char[] encoded = fEncoded;
+		final int len = encoded.length;
+		int i= 0;
+		while (i < len) {
+			final int len1 = encoded[i++];
+			int v= i + len1;
+			if (v >= len) 
+				break;
+			
+			char[] macro= extract(encoded, i, len1);
+			final int len2 = encoded[v++];
+			switch(len2) {
+			case ENCODED_UNDEFINED:
+				i= v;
+				if (!visitor.visitUndefined(macro))
+					return false;
+				break;
+			case ENCODED_DEFINED:
+				i= v;
+				if (!visitor.visitDefined(macro))
+					return false;
+				break;
+			default:
+				i= v+len2;
+				if (i > len) 
+					break;
+				if (!visitor.visitValue(macro, extract(encoded, v, len2)))
+					return false;
+				break;
+			} 
+		}
+		return true;
+	}
+
+	public char[] extract(final char[] source, int from, final int length) {
+		char[] value= new char[length];
+		System.arraycopy(source, from, value, 0, length);
+		return value;
+	}
+
+	public char[] encode() {
+		return fEncoded;
+	}
+	
+	/**
+	 * For debugging purposes.
+	 */
+	@SuppressWarnings("nls")
+	@Override
+	public String toString() {
+		final StringBuilder buf= new StringBuilder();
+		buf.append('{');
+		accept(new IVisitor() {
+			public boolean visitValue(char[] macro, char[] value) {
+				buf.append(macro).append('=').append(value).append(',');
+				return true;
+			}
+			public boolean visitUndefined(char[] macro) {
+				buf.append(macro).append('=').append("null,");
+				return true;
+			}
+			public boolean visitDefined(char[] macro) {
+				buf.append(macro).append('=').append("*,");
+				return true;
+			}
+		});
+		int buflen = buf.length();
+		if (buflen > 1)
+			buf.setLength(buflen-1);
+		buf.append('}');
+		return buf.toString();
+	}
+}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/AbstractIndexerTask.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/AbstractIndexerTask.java
index 52c0ed51bdc..6f69f48146a 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/AbstractIndexerTask.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/AbstractIndexerTask.java
@@ -15,19 +15,18 @@ package org.eclipse.cdt.internal.core.pdom;
 import java.lang.reflect.InvocationTargetException;
 import java.net.URI;
 import java.util.ArrayList;
-import java.util.Arrays;
+import java.util.BitSet;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
+import java.util.LinkedHashSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
-import java.util.Map.Entry;
 
 import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.dom.IPDOMIndexerTask;
-import org.eclipse.cdt.core.dom.ast.IASTNode;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorIncludeStatement;
 import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit;
 import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit.IDependencyTree;
@@ -42,21 +41,20 @@ import org.eclipse.cdt.core.index.IndexLocationFactory;
 import org.eclipse.cdt.core.model.AbstractLanguage;
 import org.eclipse.cdt.core.model.ILanguage;
 import org.eclipse.cdt.core.parser.FileContent;
-import org.eclipse.cdt.core.parser.IExtendedScannerInfo;
 import org.eclipse.cdt.core.parser.IParserLogService;
 import org.eclipse.cdt.core.parser.IScannerInfo;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.core.parser.IncludeFileContentProvider;
 import org.eclipse.cdt.core.parser.ParserUtil;
-import org.eclipse.cdt.core.parser.ScannerInfo;
 import org.eclipse.cdt.internal.core.dom.IIncludeFileResolutionHeuristics;
+import org.eclipse.cdt.internal.core.index.FileContentKey;
 import org.eclipse.cdt.internal.core.index.IIndexFragment;
 import org.eclipse.cdt.internal.core.index.IIndexFragmentFile;
 import org.eclipse.cdt.internal.core.index.IWritableIndex;
 import org.eclipse.cdt.internal.core.index.IndexBasedFileContentProvider;
+import org.eclipse.cdt.internal.core.parser.IMacroDictionary;
 import org.eclipse.cdt.internal.core.parser.scanner.InternalFileContentProvider;
-import org.eclipse.cdt.internal.core.parser.scanner.StreamHasher;
 import org.eclipse.cdt.utils.EFSExtensionManager;
-import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IPath;
 import org.eclipse.core.runtime.IProgressMonitor;
@@ -74,55 +72,161 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 		skip, useDefaultLanguage, useAlternateLanguage, useBoth
 	}
 	private static final int MAX_ERRORS = 500;
-	
-	private static class FileKey {
-		final URI fUri;
+
+	private static enum UpdateKind {REQUIRED_SOURCE, REQUIRED_HEADER, OTHER_HEADER}
+	private static class LinkageTask {
 		final int fLinkageID;
+		private final Map<IIndexFileLocation, LocationTask> fLocationTasks;
 		
-		public FileKey(int linkageID, URI uri) {
-			fUri= uri;
+		LinkageTask(int linkageID) {
 			fLinkageID= linkageID;
+			fLocationTasks= new HashMap<IIndexFileLocation, LocationTask>();
+		}
+		
+		boolean requestUpdate(IIndexFileLocation ifl, IIndexFragmentFile ifile, Object tu,
+				UpdateKind kind) {
+			LocationTask locTask= fLocationTasks.get(ifl);
+			if (locTask == null) {
+				locTask= new LocationTask();
+				fLocationTasks.put(ifl, locTask);
+			}
+			return locTask.requestUpdate(ifile, tu, kind);
 		}
 
-		@Override
-		public int hashCode() {
-			return fUri.hashCode() * 31 + fLinkageID;
+		LocationTask find(IIndexFileLocation ifl) {
+			return fLocationTasks.get(ifl);
 		}
+	}
 
-		@Override
-		public boolean equals(Object obj) {
-			FileKey other = (FileKey) obj;
-			return fLinkageID == other.fLinkageID && fUri.equals(other.fUri);
+	private static class LocationTask {
+		private boolean fCountedUnknownVersion;
+		private boolean fStoredAVersion;
+		Object fTu;
+		UpdateKind fKind= UpdateKind.OTHER_HEADER;
+		private List<FileVersionTask> fVersionTasks= Collections.emptyList();
+
+		/**
+		 * Requests the update of a file, returns whether the total count needs to be updated.
+		 */
+		boolean requestUpdate(IIndexFragmentFile ifile, Object tu, UpdateKind kind) {
+			if (tu != null)
+				fTu= tu;
+			if (kind != null)
+				fKind= kind;
+			
+			if (ifile == null) {
+				assert fVersionTasks.isEmpty();
+				final boolean countRequest= !fCountedUnknownVersion;
+				fCountedUnknownVersion= true;
+				return countRequest;
+			}
+
+			return addVersionTask(ifile);
+		}
+
+		/**
+		 * Return whether the task needs to be counted.
+		 */
+		private boolean addVersionTask(IIndexFragmentFile ifile) {
+			FileVersionTask fc= findVersion(ifile);
+			if (fc != null) 
+				return false;
+
+			fc= new FileVersionTask(ifile);
+			boolean countRequest= true;
+			if (fCountedUnknownVersion) {
+				fCountedUnknownVersion= false;
+				countRequest= false;
+			}
+
+			switch (fVersionTasks.size()) {
+			case 0:
+				fVersionTasks= Collections.singletonList(fc);
+				break;
+			case 1:
+				List<FileVersionTask> newList= new ArrayList<FileVersionTask>(2);
+				newList.add(fVersionTasks.get(0));
+				newList.add(fc);
+				fVersionTasks= newList;
+				break;
+			default:
+				fVersionTasks.add(fc);
+				break;
+			}
+			return countRequest;
+		}
+		
+		void removeVersionTask(Iterator<FileVersionTask> it) {
+			if (fVersionTasks.size() == 1) {
+				fVersionTasks= Collections.emptyList();
+			} else {
+				it.remove();
+			}
+		}
+
+		private FileVersionTask findVersion(IIndexFile ifile) {
+			for (FileVersionTask fc : fVersionTasks) {
+				if (fc.fIndexFile.equals(ifile))
+					return fc;
+			}
+			return null;
+		}
+
+		FileVersionTask findVersion(ISignificantMacros sigMacros) throws CoreException {
+			for (FileVersionTask fc : fVersionTasks) {
+				if (sigMacros.equals(fc.fIndexFile.getSignificantMacros()))
+					return fc;
+			}
+			return null;
+		}
+
+		boolean isCompleted() {
+			for (FileVersionTask fc : fVersionTasks) {
+				if (fc.fOutdated)
+					return false;
+			}
+			if (fKind == UpdateKind.OTHER_HEADER)
+				return true;
+			
+			return fStoredAVersion;
+		}
+
+		public boolean needsVersion() {
+			if (fKind == UpdateKind.OTHER_HEADER)
+				return false;
+
+			return !fStoredAVersion;
 		}
 	}
 
+	public static class FileVersionTask {
+		private final IIndexFragmentFile fIndexFile;
+		private boolean fOutdated;
+
+		FileVersionTask(IIndexFragmentFile file) {
+			fIndexFile= file;
+			fOutdated= true;
+		}
+		
+		void setUpdated() {
+			fOutdated= false;
+		}
+	}
+		
 	public static class IndexFileContent {
-		private IIndexFile fIndexFile;
-		private boolean fRequestUpdate;
-		private boolean fRequestIsCounted= true;
-		private boolean fIsUpdated;
 		private Object[] fPreprocessingDirectives;
 		private ICPPUsingDirective[] fDirectives;
 
-		public IndexFileContent() {
-			fRequestIsCounted = true;
+		public IndexFileContent(IIndexFile ifile) throws CoreException {
+			setPreprocessorDirectives(ifile.getIncludes(), ifile.getMacros());
+			setUsingDirectives(ifile.getUsingDirectives());
 		}
 
 		public Object[] getPreprocessingDirectives() throws CoreException {
-			if (fPreprocessingDirectives == null) {
-				if (fIndexFile == null)
-					return new Object[0];
-				setPreprocessorDirectives(fIndexFile.getIncludes(), fIndexFile.getMacros());
-			}
 			return fPreprocessingDirectives;
 		}
 		
 		public ICPPUsingDirective[] getUsingDirectives() throws CoreException {
-			if (fDirectives == null) {
-				if (fIndexFile == null)
-					return ICPPUsingDirective.EMPTY_ARRAY;
-				setUsingDirectives(fIndexFile.getUsingDirectives());
-			}
 			return fDirectives;
 		}
 
@@ -134,11 +238,6 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 			fDirectives= usingDirectives;
 		}
 
-		public void clearCaches() {
-			fPreprocessingDirectives= null;
-			fDirectives= null;
-		}
-		
 		public static Object[] merge(IIndexInclude[] includes, IIndexMacro[] macros) throws CoreException {
 			Object[] merged= new Object[includes.length + macros.length];
 			int i= 0;
@@ -177,11 +276,12 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 	private int fUpdateFlags= IIndexManager.UPDATE_ALL;
 	private UnusedHeaderStrategy fIndexHeadersWithoutContext= UnusedHeaderStrategy.useDefaultLanguage;
 	private boolean fIndexFilesWithoutConfiguration= true;
-	private HashMap<FileKey, IndexFileContent> fFileInfos= new HashMap<FileKey, IndexFileContent>();
-
+	private List<LinkageTask> fRequestsPerLinkage= new ArrayList<LinkageTask>();
+	private Map<IIndexFile, IndexFileContent> fIndexContentCache= new HashMap<IIndexFile, IndexFileContent>();
+	private Map<IIndexFileLocation, IIndexFile[]> fIndexFilesCache= new HashMap<IIndexFileLocation, IIndexFile[]>();
+	
 	private Object[] fFilesToUpdate;
 	private List<Object> fFilesToRemove = new ArrayList<Object>();
-	private List<String> fFilesUpFront= new ArrayList<String>();
 	private int fASTOptions;
 	private int fForceNumberFiles= 0;
 	
@@ -197,7 +297,7 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 	 */
 	private final LinkedList<AbstractIndexerTask> fUrgentTasks;
 	boolean fTaskCompleted;
-
+	private IndexerProgress fInfo= new IndexerProgress();
 	public AbstractIndexerTask(Object[] filesToUpdate, Object[] filesToRemove,
 			IndexerInputAdapter resolver, boolean fastIndexer) {
 		super(resolver);
@@ -228,8 +328,8 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 		fUpdateFlags= flags;
 	}
 
+	// TODO(197989) remove
 	public final void setParseUpFront(String[] astFilePaths) {
-		fFilesUpFront.addAll(Arrays.asList(astFilePaths));
 	}
 
 	public final void setForceFirstFiles(int number) {
@@ -240,94 +340,120 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 		fFileSizeLimit= limit;
 	}
 
+	/**
+	 * @see IPDOMIndexerTask#acceptUrgentTask(IPDOMIndexerTask)
+	 */
+	public synchronized boolean acceptUrgentTask(IPDOMIndexerTask urgentTask) {
+		if (!(urgentTask instanceof AbstractIndexerTask)) {
+			return false;
+		}
+		AbstractIndexerTask task = (AbstractIndexerTask) urgentTask; 
+		if (task.fIsFastIndexer != fIsFastIndexer ||
+				task.fIndexFilesWithoutConfiguration != fIndexFilesWithoutConfiguration ||
+				(fIndexFilesWithoutConfiguration && task.fIndexHeadersWithoutContext != fIndexHeadersWithoutContext) ||
+				fTaskCompleted) {
+			// Reject the urgent work since this task is not capable of doing it, or it's too late.
+			return false;
+		}
+		if (task.fFilesToUpdate.length >
+				(fFilesToUpdate != null ? fFilesToUpdate.length : getProgressInformation().fRequestedFilesCount)) {
+			// Reject the urgent work since it's too heavy for this task.
+			return false;
+		}
+		fUrgentTasks.add(task);
+		return true;
+	}
+	
+	private synchronized boolean hasUrgentTasks() {
+		return !fUrgentTasks.isEmpty();
+	}
+
+	/**
+	 * Retrieves the first urgent task from the queue of urgent tasks.
+	 * @return An urgent task, or {@code null} if there are no urgent tasks.
+	 */
+	private synchronized AbstractIndexerTask getUrgentTask() {
+		return fUrgentTasks.poll();
+	}
+
 	protected abstract IWritableIndex createIndex();
 	protected abstract IIncludeFileResolutionHeuristics createIncludeHeuristics();
 	protected abstract IncludeFileContentProvider createReaderFactory();
-	protected abstract AbstractLanguage[] getLanguages(String fileName);
-
 	protected ITodoTaskUpdater createTodoTaskUpdater() {
 		return null;
 	}
-	
-	protected IScannerInfo createDefaultScannerConfig(int linkageID) {
-		return new ScannerInfo();
+		
+	/**
+	 * @return array of linkage IDs that shall be parsed
+	 */
+	protected int[] getLinkagesToParse() {
+		return PDOMManager.IDS_FOR_LINKAGES_TO_INDEX;
 	}
-	
-	protected String getASTPathForParsingUpFront() {
-		return "______"; //$NON-NLS-1$
+
+	protected IParserLogService getLogService() {
+		return ParserUtil.getParserLogService();
+	}
+
+	protected void logError(IStatus s) {
+		CCorePlugin.log(s);
+	}
+
+	protected void logException(Throwable e) {
+		CCorePlugin.log(e);
 	}
 
-	private final IASTTranslationUnit createAST(String code, AbstractLanguage lang, IScannerInfo scanInfo,
-			int options, IProgressMonitor monitor) throws CoreException {
-		String dummyName= getASTPathForParsingUpFront();
-		if (dummyName != null) {
-			IIndexFileLocation dummyLoc= fResolver.resolveASTPath(dummyName);
-			setIndexed(lang.getLinkageID(), dummyLoc);
-			FileContent codeReader= FileContent.create(dummyName, code.toCharArray());
-			return createAST(lang, codeReader, scanInfo, options, false, monitor);
+	protected String getMessage(MessageKind kind, Object... arguments) {
+		switch (kind) {
+		case parsingFileTask:
+			return NLS.bind(Messages.AbstractIndexerTask_parsingFileTask, arguments);
+		case errorWhileParsing:
+			return NLS.bind(Messages.AbstractIndexerTask_errorWhileParsing, arguments);
+		case tooManyIndexProblems:
+			return Messages.AbstractIndexerTask_tooManyIndexProblems;
 		}
 		return null;
 	}
-	
 
-	private final IASTTranslationUnit createAST(Object tu, AbstractLanguage language, FileContent codeReader,
-			IScannerInfo scanInfo, int options, boolean inContext, IProgressMonitor pm) throws CoreException {
-		if (codeReader == null) {
-			return null;
-		}
-		if (fResolver.isSourceUnit(tu)) {
-			options |= ILanguage.OPTION_IS_SOURCE_UNIT;
+	/**
+	 * Makes a copy of the current progress information and returns it.
+	 * @since 4.0
+	 */
+	public IndexerProgress getProgressInformation() {
+		synchronized (fInfo) {
+			return new IndexerProgress(fInfo);
 		}
-		return createAST(language, codeReader, scanInfo, options, inContext, pm);
 	}
 
-	private final IASTTranslationUnit createAST(AbstractLanguage language, FileContent codeReader,
-			IScannerInfo scanInfo, int options, boolean inContext, IProgressMonitor pm) throws CoreException {
-		if (fFileSizeLimit > 0 && fResolver.getFileSize(codeReader.getFileLocation()) > fFileSizeLimit) {
-			if (fShowActivity) {
-				trace("Indexer: Skipping large file " + codeReader.getFileLocation());  //$NON-NLS-1$ 
-			}
-			return null;
+	/**
+	 * Updates current progress information with the provided delta.
+	 */
+	private final void updateFileCount(int sources, int primaryHeader, int header) {
+		synchronized (fInfo) {
+			fInfo.fCompletedSources += sources;
+			fInfo.fPrimaryHeaderCount += primaryHeader;
+			fInfo.fCompletedHeaders += header;
 		}
-		if (fCodeReaderFactory == null) {
-			InternalFileContentProvider fileContentProvider = createInternalFileContentProvider();
-			if (fIsFastIndexer) {
-				IndexBasedFileContentProvider ibfcp = new IndexBasedFileContentProvider(fIndex, fResolver,
-						language.getLinkageID(), fileContentProvider, this);
-				ibfcp.setSupportFillGapFromContextToHeader(inContext);
-				ibfcp.setFileSizeLimit(fFileSizeLimit);
-				fCodeReaderFactory= ibfcp;
+	}
+	
+	private final void reportFile(boolean wasCounted, UpdateKind kind) {
+		if (wasCounted) {
+			if (kind == UpdateKind.REQUIRED_SOURCE) {
+				updateFileCount(1, 0, 0);
 			} else {
-				fCodeReaderFactory= fileContentProvider;
-			}
-		} else if (fIsFastIndexer) {
-			((IndexBasedFileContentProvider) fCodeReaderFactory).setLinkage(language.getLinkageID());
-		}
-		fCodeReaderFactory.setIncludeResolutionHeuristics(createIncludeHeuristics());
-		try {
-			IASTTranslationUnit ast= language.getASTTranslationUnit(codeReader, scanInfo, fCodeReaderFactory,
-					fIndex, options, getLogService());
-			if (pm.isCanceled()) {
-				return null;
-			}
-			return ast;
-		} finally {
-			if (fIsFastIndexer) {
-				((IndexBasedFileContentProvider) fCodeReaderFactory).cleanupAfterTranslationUnit();
+				updateFileCount(0, 1, 1);
 			}
+		} else {
+			updateFileCount(0, 0, 1);
 		}
 	}
 
-	private InternalFileContentProvider createInternalFileContentProvider() {
-		final IncludeFileContentProvider fileContentProvider = createReaderFactory();
-		if (fileContentProvider instanceof InternalFileContentProvider)
-			return (InternalFileContentProvider) fileContentProvider;
-		
-		throw new IllegalArgumentException("Invalid file content provider"); //$NON-NLS-1$
-	}
-
-	protected IParserLogService getLogService() {
-		return ParserUtil.getParserLogService();
+	/**
+	 * Updates current progress information with the provided delta.
+	 */
+	private final void incrementRequestedFilesCount(int delta) {
+		synchronized (fInfo) {
+			fInfo.fRequestedFilesCount += delta;
+		}
 	}
 
 	public final void runTask(IProgressMonitor monitor) throws InterruptedException {
@@ -354,7 +480,7 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 			try {
 				try {
 					// Split into sources and headers, remove excluded sources.
-					HashMap<Integer, List<Object>> files= new HashMap<Integer, List<Object>>();
+					HashMap<Integer, List<IIndexFileLocation>> files= new HashMap<Integer, List<IIndexFileLocation>>();
 					final ArrayList<IIndexFragmentFile> indexFilesToRemove= new ArrayList<IIndexFragmentFile>();
 					extractFiles(files, indexFilesToRemove, monitor);
 	
@@ -362,13 +488,16 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 	
 					// Remove files from index
 					removeFilesInIndex(fFilesToRemove, indexFilesToRemove, monitor);
-	
-					parseFilesUpFront(monitor);
 
-					HashMap<Integer, List<Object>> moreFiles= null;
+					HashMap<Integer, List<IIndexFileLocation>> moreFiles= null;
 					while (true) {
 						for (int linkageID : getLinkagesToParse()) {
-							parseLinkage(linkageID, files, monitor);
+							final List<IIndexFileLocation> filesForLinkage = files.get(linkageID);
+							if (filesForLinkage != null) {
+								parseLinkage(linkageID, filesForLinkage, monitor);
+								fIndexContentCache.clear();
+								fIndexFilesCache.clear();
+							}
 							if (hasUrgentTasks())
 								break;
 						}
@@ -390,8 +519,8 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 							if (moreFiles == null) {
 								moreFiles = files;
 							} else {
-								for (Map.Entry<Integer, List<Object>> entry : files.entrySet()) {
-									List<Object> list= moreFiles.get(entry.getKey());
+								for (Map.Entry<Integer, List<IIndexFileLocation>> entry : files.entrySet()) {
+									List<IIndexFileLocation> list= moreFiles.get(entry.getKey());
 									if (list == null) {
 										moreFiles.put(entry.getKey(), entry.getValue());
 									} else {
@@ -400,7 +529,7 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 								}							
 							}
 							// Extract files from the urgent task.
-							files = new HashMap<Integer, List<Object>>();
+							files = new HashMap<Integer, List<IIndexFileLocation>>();
 							fFilesToUpdate = urgentTask.fFilesToUpdate;
 							fForceNumberFiles = urgentTask.fForceNumberFiles;
 							fFilesToRemove = urgentTask.fFilesToRemove;
@@ -427,49 +556,24 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 		}
 	}
 
-	/**
-	 * @see IPDOMIndexerTask#acceptUrgentTask(IPDOMIndexerTask)
-	 */
-	public synchronized boolean acceptUrgentTask(IPDOMIndexerTask urgentTask) {
-		if (!(urgentTask instanceof AbstractIndexerTask)) {
-			return false;
-		}
-		AbstractIndexerTask task = (AbstractIndexerTask) urgentTask; 
-		if (!task.fFilesUpFront.isEmpty() ||
-				task.fIsFastIndexer != fIsFastIndexer ||
-				task.fIndexFilesWithoutConfiguration != fIndexFilesWithoutConfiguration ||
-				(fIndexFilesWithoutConfiguration && task.fIndexHeadersWithoutContext != fIndexHeadersWithoutContext) ||
-				fTaskCompleted) {
-			// Reject the urgent work since this task is not capable of doing it, or it's too late.
-			return false;
-		}
-		if (task.fFilesToUpdate.length >
-				(fFilesToUpdate != null ? fFilesToUpdate.length : getProgressInformation().fRequestedFilesCount)) {
-			// Reject the urgent work since it's too heavy for this task.
-			return false;
-		}
-		fUrgentTasks.add(task);
-		return true;
-	}
-
 	private void setResume(boolean value) throws InterruptedException, CoreException {
-		fIndex.acquireWriteLock(1);
+		fIndex.acquireWriteLock();
 		try {
 			fIndex.getWritableFragment().setProperty(IIndexFragment.PROPERTY_RESUME_INDEXER, String.valueOf(value)); 
 		} finally {
-			fIndex.releaseWriteLock(1);
+			fIndex.releaseWriteLock();
 		}
 	}
 
-	private void extractFiles(HashMap<Integer, List<Object>> files, List<IIndexFragmentFile> iFilesToRemove,
+	private void extractFiles(HashMap<Integer, List<IIndexFileLocation>> files, List<IIndexFragmentFile> iFilesToRemove,
 			IProgressMonitor monitor) throws CoreException {
 		final boolean forceAll= (fUpdateFlags & IIndexManager.UPDATE_ALL) != 0;
 		final boolean checkTimestamps= (fUpdateFlags & IIndexManager.UPDATE_CHECK_TIMESTAMPS) != 0;
 		final boolean checkFileContentsHash = (fUpdateFlags & IIndexManager.UPDATE_CHECK_CONTENTS_HASH) != 0;
-		final boolean checkConfig= (fUpdateFlags & IIndexManager.UPDATE_CHECK_CONFIGURATION) != 0;
 
 		int count= 0;
 		int forceFirst= fForceNumberFiles;
+		BitSet linkages= new BitSet();
 		for (final Object tu : fFilesToUpdate) {
 			if (monitor.isCanceled())
 				return;
@@ -480,39 +584,35 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 				continue;
 			
 			final IIndexFragmentFile[] indexFiles= fIndex.getWritableFiles(ifl);
-			if (!fResolver.isIndexedOnlyIfIncluded(tu)) {
-				final boolean isSourceUnit= fResolver.isSourceUnit(tu);
-				final boolean isExcludedSource= isSourceUnit && !fIndexFilesWithoutConfiguration && !fResolver.isFileBuildConfigured(tu);
-
-				if ((isSourceUnit && !isExcludedSource) || fIndexHeadersWithoutContext != UnusedHeaderStrategy.skip ||
-						fResolver.isIndexedUnconditionally(ifl)) {
-					// Headers or sources required with a specific linkage
-					AbstractLanguage[] langs= fResolver.getLanguages(tu, fIndexHeadersWithoutContext == UnusedHeaderStrategy.useBoth);
-					for (AbstractLanguage lang : langs) {
-						int linkageID = lang.getLinkageID();
-						IIndexFragmentFile ifile= getFile(linkageID, indexFiles);
-						if (ifile == null || !ifile.hasContent()) {
-							store(tu, linkageID, isSourceUnit, files);
-							requestUpdate(linkageID, ifl, null);
-							count++;
-						} else {
-							takeFile(ifile, indexFiles);
-							boolean update= false;
-							if (checkConfig) {
-								update= isSourceUnit ? isSourceUnitConfigChange(tu, ifile) : isHeaderConfigChange(tu, ifile);
-							}
-							update= update || force || isModified(checkTimestamps, checkFileContentsHash, ifl, tu, ifile);
-							if (update) {
-								requestUpdate(linkageID, ifl, ifile);
-								store(tu, linkageID, isSourceUnit, files);
+			final boolean isSourceUnit= fResolver.isSourceUnit(tu);
+			linkages.clear();
+			if (isRequiredInIndex(tu, ifl, isSourceUnit)) {
+				// Headers or sources required with a specific linkage
+				final UpdateKind updateKind = isSourceUnit ? UpdateKind.REQUIRED_SOURCE : UpdateKind.REQUIRED_HEADER;
+				AbstractLanguage[] langs= fResolver.getLanguages(tu, fIndexHeadersWithoutContext == UnusedHeaderStrategy.useBoth);
+				for (AbstractLanguage lang : langs) {
+					int linkageID = lang.getLinkageID();
+					boolean foundInLinkage = false;
+					for (int i = 0; i < indexFiles.length; i++) {
+						IIndexFragmentFile ifile = indexFiles[i];
+						if (ifile != null && ifile.getLinkageID() == linkageID && ifile.hasContent()) {
+							foundInLinkage = true;
+							indexFiles[i]= null;  // Take the file.
+							boolean update= force || isModified(checkTimestamps, checkFileContentsHash, ifl, tu, ifile);
+							if (update && requestUpdate(linkageID, ifl, ifile, tu, updateKind)) {
 								count++;
+								linkages.set(linkageID);
 							}
 						}
 					}
+					if (!foundInLinkage && requestUpdate(linkageID, ifl, null, tu, updateKind)) {
+						linkages.set(linkageID);
+						count++;
+					}
 				}
 			}
 			
-			// handle other files present in index
+			// Handle other files present in index.
 			for (IIndexFragmentFile ifile : indexFiles) {
 				if (ifile != null) {
 					IIndexInclude ctx= ifile.getParsedInContext();
@@ -520,20 +620,18 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 						iFilesToRemove.add(ifile);
 						count++;
 					} else {
-						boolean update= false;
-						if (checkConfig) {
-							update= isHeaderConfigChange(tu, ifile);
-						}
-						update= update || force || isModified(checkTimestamps, checkFileContentsHash, ifl, tu, ifile);
-						if (update) {
-							final int linkageID = ifile.getLinkageID();
-							requestUpdate(linkageID, ifl, ifile);
-							store(tu, linkageID, false, files);
+						boolean update= force || isModified(checkTimestamps, checkFileContentsHash, ifl, tu, ifile);
+						final int linkageID = ifile.getLinkageID();
+						if (update && requestUpdate(linkageID, ifl, ifile, tu, UpdateKind.OTHER_HEADER)) {
 							count++;
+							linkages.set(linkageID);
 						}
 					}
 				}
 			}
+			for (int lid = linkages.nextSetBit(0); lid >= 0; lid= linkages.nextSetBit(lid+1)) {
+				addPerLinkage(lid, ifl, files);
+			}
 		}
 		synchronized (this) {
 			incrementRequestedFilesCount(count - fFilesToUpdate.length);
@@ -541,6 +639,36 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 		}
 	}
 
+	private void addPerLinkage(int linkageID, IIndexFileLocation ifl, HashMap<Integer, List<IIndexFileLocation>> files) {
+		List<IIndexFileLocation> list= files.get(linkageID);
+		if (list == null) {
+			list= new LinkedList<IIndexFileLocation>();
+			files.put(linkageID, list);
+		}
+		list.add(ifl);
+	}
+
+	private boolean isRequiredInIndex(Object tu, IIndexFileLocation ifl, boolean isSourceUnit) {
+		// External files are never required
+		if (fResolver.isIndexedOnlyIfIncluded(tu)) 
+			return false;
+		
+		// User preference to require all
+		if (fIndexHeadersWithoutContext != UnusedHeaderStrategy.skip)
+			return true;
+		
+		// File required because it is open in the editor.
+		if (fResolver.isIndexedUnconditionally(ifl))
+			return true;
+		
+		// Source file
+		if (isSourceUnit) {
+			if (fIndexFilesWithoutConfiguration || fResolver.isFileBuildConfigured(tu))
+				return true;
+		}
+		return false;
+	}
+
 	private boolean isModified(boolean checkTimestamps, boolean checkFileContentsHash, IIndexFileLocation ifl,
 			Object tu, IIndexFragmentFile file)	throws CoreException {
 		if (checkTimestamps) {
@@ -555,84 +683,64 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 		return false;
 	}
 
-	private void requestUpdate(int linkageID, IIndexFileLocation ifl, IIndexFragmentFile ifile) {
-		FileKey key= new FileKey(linkageID, ifl.getURI());
-		IndexFileContent info= fFileInfos.get(key);
-		if (info == null) {
-			info= createFileInfo(key, null);
-		}
-		info.fIndexFile= ifile;
-		info.fRequestUpdate= true;
-		info.fIsUpdated= false;
-	}
-	
-	private void setIndexed(int linkageID, IIndexFileLocation ifl) {
-		FileKey key= new FileKey(linkageID, ifl.getURI());
-		IndexFileContent info= fFileInfos.get(key);
-		if (info == null) {
-			info= createFileInfo(key, null);
-		}
-		info.fIsUpdated= true;
-		info.clearCaches();
-	}
-
-	private IndexFileContent createFileInfo(FileKey key, IIndexFile ifile) {
-		IndexFileContent info = new IndexFileContent();
-		fFileInfos.put(key, info);
-		info.fIndexFile= ifile;
-		return info;
-	}
-
-	private IndexFileContent getFileInfo(int linkageID, IIndexFileLocation ifl) {
-		FileKey key= new FileKey(linkageID, ifl.getURI());
-		return fFileInfos.get(key);
-	}
-
-	private boolean isSourceUnitConfigChange(Object tu, IIndexFragmentFile ifile) {
-		return false;
+	private long computeFileContentsHash(Object tu) {
+		FileContent codeReader= fResolver.getCodeReader(tu);
+		return codeReader != null ? codeReader.getContentsHash() : 0;
 	}
 
-	private boolean isHeaderConfigChange(Object tu, IIndexFragmentFile ifile) {
-		return false;
+	private boolean requestUpdate(int linkageID, IIndexFileLocation ifl, IIndexFragmentFile ifile, Object tu, UpdateKind kind) {
+		LinkageTask fileMap= createRequestMap(linkageID);
+		return fileMap.requestUpdate(ifl, ifile, tu, kind);
 	}
 	
-	private IIndexFragmentFile getFile(int linkageID, IIndexFragmentFile[] indexFiles) throws CoreException {
-		for (IIndexFragmentFile ifile : indexFiles) {
-			if (ifile != null && ifile.getLinkageID() == linkageID) {
-				return ifile;
-			}
+	private LinkageTask createRequestMap(int linkageID) {
+		LinkageTask map= findRequestMap(linkageID);
+		if (map == null) {
+			map= new LinkageTask(linkageID);
+			fRequestsPerLinkage.add(map);
 		}
-		return null;
+		return map;
 	}
 
-	private void takeFile(IIndexFragmentFile ifile, IIndexFragmentFile[] indexFiles) {
-		for (int i = 0; i < indexFiles.length; i++) {
-			if (indexFiles[i] == ifile) {
-				indexFiles[i]= null;
-				return;
-			}
+	private LinkageTask findRequestMap(int linkageID) {
+		for (LinkageTask map : fRequestsPerLinkage) {
+			if (map.fLinkageID == linkageID)
+				return map;
 		}
+		return null;
 	}
-
-	private void store(Object tu, int linkageID, boolean isSourceUnit, HashMap<Integer, List<Object>> files) {
-		Integer key = getFileListKey(linkageID, isSourceUnit);
-		List<Object> list= files.get(key);
-		if (list == null) {
-			list= new LinkedList<Object>();
-			files.put(key, list);
+	
+	@Override
+	protected void reportFileWrittenToIndex(FileInAST file, IIndexFragmentFile ifile) throws CoreException {
+		final FileContentKey fck = file.fFileContentKey;
+		boolean wasCounted= false;
+		UpdateKind kind= UpdateKind.OTHER_HEADER;
+		LinkageTask map = findRequestMap(fck.getLinkageID());
+		if (map != null) {
+			LocationTask locTask = map.find(fck.getLocation());
+			if (locTask != null) {
+				kind= locTask.fKind;
+				FileVersionTask v = locTask.findVersion(ifile);
+				if (v != null) {
+					wasCounted= v.fOutdated;
+					v.setUpdated();
+				} else {
+					// We have added a version, the request is fulfilled.
+					wasCounted= locTask.fCountedUnknownVersion;
+					locTask.fCountedUnknownVersion= false;
+				}
+				locTask.fStoredAVersion= true;
+			}
 		}
-		list.add(tu);
-	}
-
-	private Integer getFileListKey(int linkageID, boolean isSourceUnit) {
-		Integer key= new Integer(linkageID * 2 + (isSourceUnit ? 0 : 1));
-		return key;
+		fIndexContentCache.remove(ifile);
+		fIndexFilesCache.remove(file.fFileContentKey.getLocation());
+		reportFile(wasCounted, kind);
 	}
 
 	private void removeFilesInIndex(List<Object> filesToRemove, List<IIndexFragmentFile> indexFilesToRemove,
 			IProgressMonitor monitor) throws InterruptedException, CoreException {
 		if (!filesToRemove.isEmpty() || !indexFilesToRemove.isEmpty()) {
-			fIndex.acquireWriteLock(1);
+			fIndex.acquireWriteLock();
 			try {
 				for (Object tu : filesToRemove) {
 					if (monitor.isCanceled()) {
@@ -643,7 +751,7 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 						continue;
 					IIndexFragmentFile[] ifiles= fIndex.getWritableFiles(ifl);
 					for (IIndexFragmentFile ifile : ifiles) {
-						fIndex.clearFile(ifile, null);
+						fIndex.clearFile(ifile);
 					}
 					incrementRequestedFilesCount(-1);
 				}
@@ -651,205 +759,182 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 					if (monitor.isCanceled()) {
 						return;
 					}
-					fIndex.clearFile(ifile, null);
+					fIndex.clearFile(ifile);
 					incrementRequestedFilesCount(-1);
 				}
 			} finally {
-				fIndex.releaseWriteLock(1);
+				fIndex.releaseWriteLock();
 			}
 		}
 		filesToRemove.clear();
 	}
 	
-	private void parseFilesUpFront(IProgressMonitor monitor) throws CoreException {
-		for (String upfront : fFilesUpFront) {
-			if (monitor.isCanceled()) {
-				return;
-			}
-			String filePath = upfront;
-			filePath= filePath.trim();
-			if (filePath.length() == 0) {
-				continue;
-			}
-			final IPath path= new Path(filePath);
-			final String fileName = path.lastSegment();
-			try {
-				monitor.subTask(getMessage(MessageKind.parsingFileTask,
-						fileName, path.removeLastSegments(1).toString()));
-				
-				AbstractLanguage[] langs= getLanguages(fileName);
-				for (AbstractLanguage lang : langs) {
-					if (fShowActivity) {
-						trace("Indexer: " + lang.getName() + ": Parsing " + filePath + " up front");  //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
-					}
-					int linkageID= lang.getLinkageID();
-					String code= "#include \"" + filePath + "\"\n";  //$NON-NLS-1$ //$NON-NLS-2$
-					
-					IScannerInfo scanInfo= createDefaultScannerConfig(linkageID);
-					if (scanInfo != null) {
-						long start= System.currentTimeMillis();
-						IASTTranslationUnit ast= createAST(code, lang, scanInfo, fASTOptions, monitor);
-						fStatistics.fParsingTime += System.currentTimeMillis() - start;
-						if (ast != null) {
-							if (fShowActivity || fShowInclusionProblems) {
-								IASTNode node= ast.getNodeSelector(null).findEnclosingNode(0,6);
-								if (node instanceof IASTPreprocessorIncludeStatement) {
-									IASTPreprocessorIncludeStatement p= (IASTPreprocessorIncludeStatement) node;
-									String found= p.getPath();
-									if (found != null) {
-										IIndexFileLocation ifl= fResolver.resolveASTPath(found);
-										IndexFileContent fileinfo = getFileInfo(linkageID, ifl);
-										if (fileinfo != null) {
-											if (fileinfo.fIndexFile != null) {
-												trace(filePath + " was not properly parsed up front for " + lang.getName()); //$NON-NLS-1$
-											}
-										}
-									}
-								}
-							}
-							writeToIndex(linkageID, ast, StreamHasher.hash(code), computeHashCode(scanInfo),
-									monitor);
-							updateFileCount(0, 0, 1);
-						}
-					}
-				}
-			} catch (Exception e) {
-				swallowError(path, e);
-			} catch (Error e) {
-				swallowError(path, e);
-			}
-		}
-		fFilesUpFront.clear();
-	}
-	
-	private void parseLinkage(int linkageID, Map<Integer, List<Object>> fileListMap, IProgressMonitor monitor)
+	private void parseLinkage(int linkageID, List<IIndexFileLocation> files, IProgressMonitor monitor)
 			throws CoreException, InterruptedException {
-		// Sources
-		List<Object> files= fileListMap.get(getFileListKey(linkageID, true));
-		if (files != null) {
-			for (Iterator<Object> iter = files.iterator(); iter.hasNext();) {
-				Object tu = iter.next();
+		LinkageTask map = findRequestMap(linkageID);
+		if (map == null || files == null || files.isEmpty())
+			return;
+		
+		// First parse the required sources
+		for (Iterator<IIndexFileLocation> it= files.iterator(); it.hasNext();) {
+			IIndexFileLocation ifl= it.next();
+			LocationTask locTask = map.find(ifl);
+			if (locTask == null || locTask.isCompleted()) {
+				it.remove();
+			} else if (locTask.fKind == UpdateKind.REQUIRED_SOURCE) {
 				if (monitor.isCanceled() || hasUrgentTasks())
 					return;
-
-				final IIndexFileLocation ifl = fResolver.resolveFile(tu);
-				if (ifl != null) {
-					final IndexFileContent info= getFileInfo(linkageID, ifl);
-					if (info != null && info.fRequestUpdate && !info.fIsUpdated) {
-						info.fRequestIsCounted= false;
-						final IScannerInfo scannerInfo= fResolver.getBuildConfiguration(linkageID, tu);
-						parseFile(tu, linkageID, ifl, scannerInfo, false, monitor);
-						if (info.fIsUpdated) {
-							updateFileCount(1, 0, 0);	// a source file was parsed
-						}
+				final Object tu = locTask.fTu;
+				final IScannerInfo scannerInfo= fResolver.getBuildConfiguration(linkageID, tu);
+				parseFile(tu, linkageID, ifl, scannerInfo, null, monitor);
+			}
+		}
+		
+		// Files with context
+		for (Iterator<IIndexFileLocation> it= files.iterator(); it.hasNext();) {
+			IIndexFileLocation ifl= it.next();
+			LocationTask locTask = map.find(ifl);
+			if (locTask == null || locTask.isCompleted()) {
+				it.remove();
+			} else {
+				for (FileVersionTask versionTask : locTask.fVersionTasks) {
+					if (versionTask.fOutdated) {
+						if (monitor.isCanceled() || hasUrgentTasks())
+							return;
+						parseVersionInContext(linkageID, map, ifl, versionTask, locTask.fTu,
+								new LinkedHashSet<IIndexFile>(), monitor);
 					}
 				}
-				iter.remove();
 			}
 		}
 		
-		// Headers with context
-		HashMap<IIndexFragmentFile, Object> contextMap= new HashMap<IIndexFragmentFile, Object>();
-		files= fileListMap.get(getFileListKey(linkageID, false));
-		if (files != null) {
-			for (Iterator<Object> iter = files.iterator(); iter.hasNext();) {
-				if (monitor.isCanceled() || hasUrgentTasks())
-					return;
-
-				final Object header= iter.next();
-				final IIndexFileLocation ifl = fResolver.resolveFile(header);
-				final IndexFileContent info= getFileInfo(linkageID, ifl);
-				if (info != null && info.fRequestUpdate && !info.fIsUpdated) {
-					if (info.fIndexFile != null && fIndex.isWritableFile(info.fIndexFile)) {
-						Object tu= findContext(linkageID, (IIndexFragmentFile) info.fIndexFile, contextMap);
-						if (tu != null) {
-							final IScannerInfo scannerInfo= fResolver.getBuildConfiguration(linkageID, tu);
-							info.fRequestIsCounted= false;
-							parseFile(header, linkageID, ifl, scannerInfo, true, monitor);
-							if (info.fIsUpdated) {
-								updateFileCount(0, 1, 1);	// a header was parsed in context
-								iter.remove();
-							}
-						}
-					}
-				} else {
-					// The file has been parsed already.
-					iter.remove();
+		// Files without context
+		for (Iterator<IIndexFileLocation> it= files.iterator(); it.hasNext();) {
+			IIndexFileLocation ifl= it.next();
+			LocationTask locTask = map.find(ifl);
+			if (locTask == null || locTask.isCompleted()) {
+				it.remove();
+			} else {
+				if (locTask.needsVersion()) {
+					if (monitor.isCanceled() || hasUrgentTasks())
+						return;
+					final Object tu = locTask.fTu;
+					final IScannerInfo scannerInfo= fResolver.getBuildConfiguration(linkageID, tu);
+					parseFile(tu, linkageID, ifl, scannerInfo, null, monitor);
+					if (locTask.isCompleted())
+						it.remove();
+					
 				}
 			}
+		}
 
-			// Headers without context
-			contextMap= null;
-			for (Iterator<Object> iter = files.iterator(); iter.hasNext();) {
-				if (monitor.isCanceled() || hasUrgentTasks())
-					return;
-
-				final Object header= iter.next();
-				final IIndexFileLocation ifl = fResolver.resolveFile(header);
-				final IndexFileContent info= getFileInfo(linkageID, ifl);
-				if (info != null && info.fRequestUpdate && !info.fIsUpdated) {
-					info.fRequestIsCounted= false;
-					final IScannerInfo scannerInfo= fResolver.getBuildConfiguration(linkageID, header);
-					parseFile(header, linkageID, ifl, scannerInfo, false, monitor);
-					if (info.fIsUpdated) {
-						updateFileCount(0, 1, 1);	// a header was parsed without context
+		// Delete remaining files.
+		fIndex.acquireWriteLock();
+		try {
+			for (IIndexFileLocation ifl : files) {
+				LocationTask locTask = map.find(ifl);
+				if (locTask != null && !locTask.isCompleted()) {
+					if (!locTask.needsVersion()) {
+						if (monitor.isCanceled() || hasUrgentTasks())
+							return;
+						Iterator<FileVersionTask> it= locTask.fVersionTasks.iterator();	
+						while (it.hasNext()) {
+							FileVersionTask v = it.next();
+							if (v.fOutdated) {
+								fIndex.clearFile(v.fIndexFile);
+								reportFile(true, locTask.fKind);
+								locTask.removeVersionTask(it);
+								fIndexContentCache.remove(v.fIndexFile);
+								fIndexFilesCache.remove(ifl);
+							}
+						}
 					}
 				}
-				iter.remove();
 			}
+		} finally {
+			fIndex.releaseWriteLock();
 		}
 	}
 
-	private synchronized boolean hasUrgentTasks() {
-		return !fUrgentTasks.isEmpty();
-	}
+	private void parseVersionInContext(int linkageID, LinkageTask map, IIndexFileLocation ifl,
+			final FileVersionTask versionTask, Object tu, LinkedHashSet<IIndexFile> safeGuard,
+			IProgressMonitor monitor) throws CoreException, InterruptedException {
+		final IIndexFragmentFile headerFile = versionTask.fIndexFile;
+		
+		final int safeguardSize= safeGuard.size();
+		for(;;) {
+			// Look for a context and parse the file
+			IIndexFragmentFile ctxFile = findContextFile(linkageID, map, versionTask, safeGuard, monitor);
+			if (ctxFile == null || ctxFile == headerFile) 
+				return;
+				
+			Object contextTu= fResolver.getInputFile(ctxFile.getLocation());
+			if (contextTu == null) 
+				return;
+			
+			final IScannerInfo scannerInfo= fResolver.getBuildConfiguration(linkageID, contextTu);
+			FileContext ctx= new FileContext(ctxFile, headerFile);
+			parseFile(tu, linkageID, ifl, scannerInfo, ctx, monitor);
+			if (!ctx.fLostPragmaOnceSemantics) 
+				return;
 
-	/**
-	 * Retrieves the first urgent task from the queue of urgent tasks.
-	 * @return An urgent task, or {@code null} if there are no urgent tasks.
-	 */
-	private synchronized AbstractIndexerTask getUrgentTask() {
-		return fUrgentTasks.poll();
+			// Try the next context
+			restoreSet(safeGuard, safeguardSize);
+		}	
 	}
 
-	private static final Object NO_CONTEXT= new Object();
-	
-	private Object findContext(int linkageID, IIndexFragmentFile ifile, HashMap<IIndexFragmentFile, Object> contextMap) {
-		Object cachedContext= contextMap.get(ifile);
-		if (cachedContext != null) {
-			return cachedContext == NO_CONTEXT ? null : cachedContext;
+	private void restoreSet(LinkedHashSet<?> set, int restoreSize) {
+		for (Iterator<?> it = set.iterator(); it.hasNext();) {
+			it.next();
+			if (restoreSize == 0) {
+				it.remove();
+			} else {
+				restoreSize--;
+			} 
 		}
-		try {
-			Object context= fResolver.getInputFile(ifile.getLocation());
-			if (context != null && fResolver.isSourceUnit(context)) {
-				contextMap.put(ifile, context);
-				return context;
-			}
+	}
 
-			contextMap.put(ifile, NO_CONTEXT); // prevent recursion
-			final IIndexInclude contextInclude= ifile.getParsedInContext();
-			if (contextInclude != null) {
-				// in case we are in context of another file that will be indexed, just wait.
-				final IndexFileContent info= getFileInfo(linkageID, contextInclude.getIncludedByLocation());
-				if (info != null && info.fRequestUpdate) {
-					return null;
-				}
-				final IIndexFragmentFile contextIFile= (IIndexFragmentFile) contextInclude.getIncludedBy();
-				context= findContext(linkageID, contextIFile, contextMap);
-				if (context != null) {
-					contextMap.put(ifile, context);
-					return context;
+	private IIndexFragmentFile findContextFile(int linkageID, LinkageTask map,
+			final FileVersionTask versionTask, LinkedHashSet<IIndexFile> safeGuard, IProgressMonitor monitor)
+			throws CoreException, InterruptedException {
+		IIndexFragmentFile ctxFile= versionTask.fIndexFile;
+		for(;;) {
+			IIndexInclude ctxInclude= ctxFile.getParsedInContext();
+			if (ctxInclude == null) 
+				return ctxFile;
+
+			IIndexFragmentFile nextCtx= (IIndexFragmentFile) ctxInclude.getIncludedBy();
+			if (!fIndex.isWritableFile(nextCtx)) 
+				return ctxFile;
+
+			// Found a recursion
+			if (!safeGuard.add(nextCtx)) 
+				return null;
+				
+			final IIndexFileLocation ctxIfl = nextCtx.getLocation();
+			LocationTask ctxTask= map.find(ctxIfl);
+			if (ctxTask != null) {
+				FileVersionTask ctxVersionTask = ctxTask.findVersion(nextCtx);
+				if (ctxVersionTask != null && ctxVersionTask.fOutdated) {
+					// Handle the context first.
+					parseVersionInContext(linkageID, map, ctxIfl, ctxVersionTask, ctxTask.fTu,
+							safeGuard, monitor);
+					if (ctxVersionTask.fOutdated 		// This is unexpected.
+							|| !versionTask.fOutdated) 	// Our file was parsed.
+						return null;
+
+					// The file is no longer a context, look for a different one.
+					nextCtx= ctxFile;
 				}
 			}
-		} catch (CoreException e) {
-			CCorePlugin.log(e);
+			ctxFile= nextCtx;
 		}
-		return null;
 	}
 
+
 	private void parseFile(Object tu, int linkageID, IIndexFileLocation ifl, IScannerInfo scanInfo,
-			boolean inContext, IProgressMonitor pm) throws CoreException, InterruptedException {
-		IPath path= getPathForLabel(ifl);
+			FileContext ctx, IProgressMonitor pm) throws CoreException, InterruptedException {
+		IPath path= getLabel(ifl);
 		AbstractLanguage[] langs= fResolver.getLanguages(tu, true);
 		AbstractLanguage lang= null;
 		for (AbstractLanguage lang2 : langs) {
@@ -871,10 +956,12 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 					path.lastSegment(), path.removeLastSegments(1).toString()));
 			long start= System.currentTimeMillis();
 			FileContent codeReader= fResolver.getCodeReader(tu);
-			IASTTranslationUnit ast= createAST(tu, lang, codeReader, scanInfo, fASTOptions, inContext, pm);
+			IIndexFile[] ctxFiles = ctx == null ? null : new IIndexFile[] {ctx.fContext, ctx.fOldFile};
+
+			IASTTranslationUnit ast= createAST(tu, lang, codeReader, scanInfo, fASTOptions, ctxFiles, pm);
 			fStatistics.fParsingTime += System.currentTimeMillis() - start;
 			if (ast != null) {
-				writeToIndex(linkageID, ast, codeReader.getContentsHash(), computeHashCode(scanInfo), pm);
+				writeToIndex(linkageID, ast, codeReader.getContentsHash(), ctx, pm);
 			}
 		} catch (CoreException e) {
 			th= e;
@@ -894,80 +981,7 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 		}
 	}
 	
-	private void writeToIndex(final int linkageID, IASTTranslationUnit ast, long fileContentsHash,
-			int configHash, IProgressMonitor pm) throws CoreException, InterruptedException {
-		HashSet<IIndexFileLocation> enteredFiles= new HashSet<IIndexFileLocation>();
-		ArrayList<IIndexFileLocation> orderedIFLs= new ArrayList<IIndexFileLocation>();
-		
-		final IIndexFileLocation topIfl = fResolver.resolveASTPath(ast.getFilePath());
-		enteredFiles.add(topIfl);
-		IDependencyTree tree= ast.getDependencyTree();
-		IASTInclusionNode[] inclusions= tree.getInclusions();
-		for (IASTInclusionNode inclusion : inclusions) {
-			collectOrderedIFLs(linkageID, inclusion, enteredFiles, orderedIFLs);
-		}
-		
-		IndexFileContent info= getFileInfo(linkageID, topIfl);
-		if (info != null && info.fRequestUpdate && !info.fIsUpdated) {
-			orderedIFLs.add(topIfl);
-		}
-		
-		IIndexFileLocation[] ifls= orderedIFLs.toArray(new IIndexFileLocation[orderedIFLs.size()]);
-		try {
-			addSymbols(ast, ifls, fIndex, 1, false, fileContentsHash, configHash, fTodoTaskUpdater, pm);
-		} finally {
-			// mark as updated in any case, to avoid parsing files that caused an exception to be thrown.
-			for (IIndexFileLocation ifl : ifls) {
-				info= getFileInfo(linkageID, ifl);
-				Assert.isNotNull(info);
-				info.fIsUpdated= true;
-			}
-		}
-	}
-
-	private void collectOrderedIFLs(final int linkageID, IASTInclusionNode inclusion,
-			HashSet<IIndexFileLocation> enteredFiles, ArrayList<IIndexFileLocation> orderedIFLs) throws CoreException {
-		final IASTPreprocessorIncludeStatement id= inclusion.getIncludeDirective();
-		if (id.isActive() && id.isResolved()) {
-			final IIndexFileLocation ifl= fResolver.resolveASTPath(id.getPath());
-			final boolean isFirstEntry= enteredFiles.add(ifl);
-			IASTInclusionNode[] nested= inclusion.getNestedInclusions();
-			for (IASTInclusionNode element : nested) {
-				collectOrderedIFLs(linkageID, element, enteredFiles, orderedIFLs);
-			}
-			if (isFirstEntry && needToUpdateHeader(linkageID, ifl)) {
-				orderedIFLs.add(ifl);
-			}
-		}
-	}
-
-	public final boolean needToUpdateHeader(int linkageID, IIndexFileLocation ifl) throws CoreException {
-		IndexFileContent info= getFileInfo(linkageID, ifl);
-		if (info == null) {
-			IIndexFile ifile= null;
-			if (fResolver.canBePartOfSDK(ifl)) {
-				ifile= fIndex.getFile(linkageID, ifl);
-			} else {
-				IIndexFragmentFile fragFile= fIndex.getWritableFile(linkageID, ifl);
-				if (fragFile != null && fragFile.hasContent()) {
-					ifile= fragFile;
-				}
-			}
-			info= createFileInfo(new FileKey(linkageID, ifl.getURI()), ifile);
-			if (ifile == null) {
-				info.fRequestIsCounted= false;
-				info.fRequestUpdate= true;
-			}
-		}
-		final boolean needUpdate= !info.fIsUpdated && info.fRequestUpdate;
-		if (needUpdate && info.fRequestIsCounted) {
-			updateFileCount(0, 1, 0);	// total headers will be counted when written to db
-			info.fRequestIsCounted= false;
-		}
-		return needUpdate;
-	}
-
-	private IPath getPathForLabel(IIndexFileLocation ifl) {
+	private IPath getLabel(IIndexFileLocation ifl) {
 		String fullPath= ifl.getFullPath();
 		if (fullPath != null) {
 			return new Path(fullPath);
@@ -992,7 +1006,7 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 				if (CCorePlugin.PLUGIN_ID.equals(s.getPlugin()))
 					throw (CoreException) e;
 			}
-
+	
 			// mask errors in order to avoid dialog from platform
 			Throwable exception = s.getException();
 			if (exception != null) {
@@ -1021,100 +1035,226 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 		}
 		return e;
 	}
-	
-	protected void logError(IStatus s) {
-		CCorePlugin.log(s);
-	}
-	
-	protected void logException(Throwable e) {
-		CCorePlugin.log(e);
-	}
 
-	private static int computeHashCode(IScannerInfo scannerInfo) {
-		int result= 0;
-		Map<String, String> macros= scannerInfo.getDefinedSymbols();
-		if (macros != null) {
-			for (Entry<String, String> entry : macros.entrySet()) {
-				String key = entry.getKey();
-				String value = entry.getValue();
-				result= addToHashcode(result, key);
-				if (value != null && value.length() > 0) {
-					result= addToHashcode(result, value);
-				}
+	private final IASTTranslationUnit createAST(Object tu, AbstractLanguage language,
+			FileContent codeReader, IScannerInfo scanInfo, int options,
+			IIndexFile[] ctx2header, IProgressMonitor pm) throws CoreException {
+		if (codeReader == null) {
+			return null;
+		}
+		if (fResolver.isSourceUnit(tu)) {
+			options |= ILanguage.OPTION_IS_SOURCE_UNIT;
+		}
+		if (fFileSizeLimit > 0 && fResolver.getFileSize(codeReader.getFileLocation()) > fFileSizeLimit) {
+			if (fShowActivity) {
+				trace("Indexer: Skipping large file " + codeReader.getFileLocation());  //$NON-NLS-1$ 
 			}
+			return null;
 		}
-		String[] a= scannerInfo.getIncludePaths();
-		if (a != null) {
-			for (String element : a) {
-				result= addToHashcode(result, element);
-
+		if (fCodeReaderFactory == null) {
+			InternalFileContentProvider fileContentProvider = createInternalFileContentProvider();
+			if (fIsFastIndexer) {
+				IndexBasedFileContentProvider ibfcp = new IndexBasedFileContentProvider(fIndex, fResolver,
+						language.getLinkageID(), fileContentProvider, this);
+				ibfcp.setContextToHeaderGap(ctx2header);
+				ibfcp.setFileSizeLimit(fFileSizeLimit);
+				fCodeReaderFactory= ibfcp;
+			} else {
+				fCodeReaderFactory= fileContentProvider;
 			}
+			fCodeReaderFactory.setIncludeResolutionHeuristics(createIncludeHeuristics());
+		} else if (fIsFastIndexer) {
+			final IndexBasedFileContentProvider ibfcp = (IndexBasedFileContentProvider) fCodeReaderFactory;
+			ibfcp.setContextToHeaderGap(ctx2header);
+			ibfcp.setLinkage(language.getLinkageID());
+		}
+		
+		IASTTranslationUnit ast= language.getASTTranslationUnit(codeReader, scanInfo, fCodeReaderFactory,
+				fIndex, options, getLogService());
+		if (pm.isCanceled()) {
+			return null;
 		}
-		if (scannerInfo instanceof IExtendedScannerInfo) {
-			IExtendedScannerInfo esi= (IExtendedScannerInfo) scannerInfo;
-			a= esi.getIncludeFiles();
-			if (a != null) {
-				for (String element : a) {
-					result= addToHashcode(result, element);
+		return ast;
+	}
 
-				}
-			}			
-			a= esi.getLocalIncludePath();
-			if (a != null) {
-				for (String element : a) {
-					result= addToHashcode(result, element);
-				}
-			}		
-			a= esi.getMacroFiles();
-			if (a != null) {
-				for (String element : a) {
-					result= addToHashcode(result, element);
-				}
-			}		
+	private InternalFileContentProvider createInternalFileContentProvider() {
+		final IncludeFileContentProvider fileContentProvider = createReaderFactory();
+		if (fileContentProvider instanceof InternalFileContentProvider)
+			return (InternalFileContentProvider) fileContentProvider;
+		
+		throw new IllegalArgumentException("Invalid file content provider"); //$NON-NLS-1$
+	}
+
+	private void writeToIndex(final int linkageID, IASTTranslationUnit ast, long fileContentsHash,
+			FileContext ctx, IProgressMonitor pm) throws CoreException, InterruptedException {
+		HashSet<FileContentKey> enteredFiles= new HashSet<FileContentKey>();
+		ArrayList<FileInAST> orderedFileKeys= new ArrayList<FileInAST>();
+		
+		final IIndexFileLocation topIfl = fResolver.resolveASTPath(ast.getFilePath());
+		FileContentKey topKey = new FileContentKey(linkageID, topIfl, ast.getSignificantMacros());
+		enteredFiles.add(topKey);
+		IDependencyTree tree= ast.getDependencyTree();
+		IASTInclusionNode[] inclusions= tree.getInclusions();
+		for (IASTInclusionNode inclusion : inclusions) {
+			collectOrderedFileKeys(linkageID, inclusion, enteredFiles, orderedFileKeys);
+		}
+		
+		IIndexFile newFile= selectIndexFile(linkageID, topIfl, ast.getSignificantMacros());
+		if (ctx != null) {
+			orderedFileKeys.add(new FileInAST(null, topKey, fileContentsHash));
+			if (newFile != null && fIndex.isWritableFile(newFile)) {
+				// File can be reused
+				ctx.fNewFile= (IIndexFragmentFile) newFile;
+			} 
+		} else if (newFile == null) {
+			orderedFileKeys.add(new FileInAST(null, topKey, fileContentsHash));
+		}
+			
+		FileInAST[] fileKeys= orderedFileKeys.toArray(new FileInAST[orderedFileKeys.size()]);
+		try {
+			addSymbols(ast, fileKeys, fIndex, false, ctx, fTodoTaskUpdater, pm);
+		} catch (CoreException e) {
+			// Avoid parsing files again, that caused an exception to be thrown.
+			withdrawRequests(linkageID, fileKeys);
+			throw e;
+		} catch (RuntimeException e) {
+			withdrawRequests(linkageID, fileKeys);
+			throw e;
+		} catch (Error e) {
+			withdrawRequests(linkageID, fileKeys);
+			throw e;
 		}
-		return result;
 	}
 
-	private static int addToHashcode(int result, String key) {
-		return result * 31 + key.hashCode();
+	private void collectOrderedFileKeys(final int linkageID, IASTInclusionNode inclusion,
+			HashSet<FileContentKey> enteredFiles, ArrayList<FileInAST> orderedFileKeys) throws CoreException {
+		final IASTPreprocessorIncludeStatement include= inclusion.getIncludeDirective();
+		if (include.createsAST()) {
+			final IIndexFileLocation ifl= fResolver.resolveASTPath(include.getPath());
+			FileContentKey fileKey = new FileContentKey(linkageID, ifl, include.getSignificantMacros());
+			final boolean isFirstEntry= enteredFiles.add(fileKey);
+			IASTInclusionNode[] nested= inclusion.getNestedInclusions();
+			for (IASTInclusionNode element : nested) {
+				collectOrderedFileKeys(linkageID, element, enteredFiles, orderedFileKeys);
+			}
+			if (isFirstEntry && selectIndexFile(linkageID, ifl, include.getSignificantMacros()) == null) {
+				orderedFileKeys.add(new FileInAST(include, fileKey, include.getContentsHash()));
+			}
+		}
 	}
 
-	private long computeFileContentsHash(Object tu) {
-		FileContent codeReader= fResolver.getCodeReader(tu);
-		return codeReader != null ? codeReader.getContentsHash() : 0;
+	private void withdrawRequests(int linkageID, FileInAST[] fileKeys) {
+		LinkageTask map = findRequestMap(linkageID);
+		if (map != null) {
+			for (FileInAST fileKey : fileKeys) {
+				LocationTask locTask = map.find(fileKey.fFileContentKey.getLocation());
+				if (locTask != null) {
+					if (locTask.fCountedUnknownVersion) {
+						locTask.fCountedUnknownVersion= false;
+						reportFile(true, locTask.fKind);
+					} else {
+						for (FileVersionTask fc : locTask.fVersionTasks) {
+							if (fc.fOutdated) {
+								reportFile(true, locTask.fKind);
+								fc.setUpdated();
+							}
+						}
+					}
+				}
+			}
+		}
 	}
 
-	public final IndexFileContent getFileContent(int linkageID, IIndexFileLocation ifl) throws CoreException {
-		if (!needToUpdateHeader(linkageID, ifl)) {
-			IndexFileContent info= getFileInfo(linkageID, ifl);
-			Assert.isNotNull(info);
-			if (info.fIndexFile == null) {
-				info.fIndexFile= fIndex.getFile(linkageID, ifl);
-				if (info.fIndexFile == null) {
+	public final IndexFileContent getFileContent(int linkageID, IIndexFileLocation ifl,
+			IIndexFile file) throws CoreException {
+		LinkageTask map = findRequestMap(linkageID);
+		if (map != null) {
+			LocationTask request= map.find(ifl);
+			if (request != null) {
+				FileVersionTask task= request.findVersion(file);
+				if (task != null && task.fOutdated)
 					return null;
+			}
+		}
+		IndexFileContent fc= fIndexContentCache.get(file);
+		if (fc == null) {
+			fc= new IndexFileContent(file);
+			fIndexContentCache.put(file, fc);
+		}
+		return fc;
+	}
+	
+	IIndexFile selectIndexFile(int linkageID, IIndexFileLocation ifl, ISignificantMacros sigMacros) throws CoreException {
+		LinkageTask map = findRequestMap(linkageID);
+		if (map != null) {
+			LocationTask locTask= map.find(ifl);
+			if (locTask != null) {
+				FileVersionTask task = locTask.findVersion(sigMacros);
+				if (task != null) {
+					return task.fOutdated ? null : task.fIndexFile;
 				}
 			}
-			return info;
+		}
+		
+		IIndexFile[] files = getAvailableIndexFiles(linkageID, ifl);
+		for (IIndexFile file : files) {
+			if (sigMacros.equals(file.getSignificantMacros()))
+				return file;
 		}
 		return null;
 	}
-	
-	protected String getMessage(MessageKind kind, Object... arguments) {
-		switch (kind) {
-		case parsingFileTask:
-			return NLS.bind(Messages.AbstractIndexerTask_parsingFileTask, arguments);
-		case errorWhileParsing:
-			return NLS.bind(Messages.AbstractIndexerTask_errorWhileParsing, arguments);
-		case tooManyIndexProblems:
-			return Messages.AbstractIndexerTask_tooManyIndexProblems;
+
+	public IIndexFile selectIndexFile(int linkageID, IIndexFileLocation ifl, IMacroDictionary md) throws CoreException {
+		LinkageTask map = findRequestMap(linkageID);
+		if (map != null) {
+			LocationTask request= map.find(ifl);
+			if (request != null) {
+				for (FileVersionTask fileVersion : request.fVersionTasks) {
+					final IIndexFile indexFile = fileVersion.fIndexFile;
+					if (md.satisfies(indexFile.getSignificantMacros())) {
+						if (fileVersion.fOutdated)
+							return null;
+						return indexFile;
+					}
+				}
+			}
+		}
+		
+		IIndexFile[] files = getAvailableIndexFiles(linkageID, ifl);
+		for (IIndexFile indexFile : files) {
+			if (md.satisfies(indexFile.getSignificantMacros())) {
+				return indexFile;
+			}
 		}
 		return null;
 	}
 
-	/**
-	 * @return array of linkage IDs that should be parsed
-	 */
-	protected int[] getLinkagesToParse() {
-		return PDOMManager.IDS_FOR_LINKAGES_TO_INDEX;
+	public IIndexFile[] getAvailableIndexFiles(int linkageID, IIndexFileLocation ifl)
+			throws CoreException {
+		IIndexFile[] files= fIndexFilesCache.get(ifl);
+		if (files == null) {
+			if (fResolver.canBePartOfSDK(ifl)) {
+				// Check for a version in potentially another pdom.
+				files= fIndex.getFiles(linkageID, ifl);
+			} else {
+				IIndexFragmentFile[] fragFiles = fIndex.getWritableFiles(linkageID, ifl);
+				int j= 0;
+				for (int i = 0; i < fragFiles.length; i++) {
+					if (fragFiles[i].hasContent()) {
+						if (j != i)
+							fragFiles[j]= fragFiles[i];
+						j++;
+					}
+				}
+				if (j == fragFiles.length) {
+					files= fragFiles;
+				} else {
+					files= new IIndexFile[j];
+					System.arraycopy(fragFiles, 0, files, 0, j);
+				} 
+			}
+			fIndexFilesCache.put(ifl, files);
+		}
+		return files;
 	}
-}
\ No newline at end of file
+}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java
index 0c1d82decf1..019c75bc4c6 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOM.java
@@ -56,6 +56,7 @@ import org.eclipse.cdt.core.index.IIndexLocationConverter;
 import org.eclipse.cdt.core.index.IIndexMacro;
 import org.eclipse.cdt.core.index.IIndexMacroContainer;
 import org.eclipse.cdt.core.index.IndexFilter;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.core.parser.util.ArrayUtil;
 import org.eclipse.cdt.core.parser.util.CharArrayUtils;
 import org.eclipse.cdt.internal.core.dom.Linkage;
@@ -210,10 +211,11 @@ public class PDOM extends PlatformObject implements IPDOM {
 	 *  CDT 8.1 development (versions not supported on teh 8.0.x branch)
 	 *  120.0 - Enumerators in global index, bug 356235
 	 *  120.1 - Specializations of using declarations, bug 357293.
+	 *  121.0 - Multiple variants of included header file, bug 197989.
 	 */
-	private static final int MIN_SUPPORTED_VERSION= version(120, 0);
-	private static final int MAX_SUPPORTED_VERSION= version(120, Short.MAX_VALUE);
-	private static final int DEFAULT_VERSION = version(120, 1);
+	private static final int MIN_SUPPORTED_VERSION= version(121, 0);
+	private static final int MAX_SUPPORTED_VERSION= version(121, Short.MAX_VALUE);
+	private static final int DEFAULT_VERSION = version(121, 0);
 
 	private static int version(int major, int minor) {
 		return (major << 16) + minor;
@@ -419,6 +421,7 @@ public class PDOM extends PlatformObject implements IPDOM {
 		return fileIndex;
 	}
 
+	@Deprecated
 	public PDOMFile getFile(int linkageID, IIndexFileLocation location) throws CoreException {
 		PDOMLinkage linkage= getLinkage(linkageID);
 		if (linkage == null)
@@ -426,8 +429,25 @@ public class PDOM extends PlatformObject implements IPDOM {
 		return PDOMFile.findFile(linkage, getFileIndex(), location, locationConverter);
 	}
 
-	public PDOMFile getFile(PDOMLinkage linkage, IIndexFileLocation location) throws CoreException {
-		return PDOMFile.findFile(linkage, getFileIndex(), location, locationConverter);
+	public PDOMFile getFile(int linkageID, IIndexFileLocation location,
+			ISignificantMacros macroDictionary) throws CoreException {
+		PDOMLinkage linkage= getLinkage(linkageID);
+		if (linkage == null)
+			return null;
+		return PDOMFile.findFile(linkage, getFileIndex(), location, locationConverter,
+				macroDictionary);
+	}
+
+	public PDOMFile getFile(PDOMLinkage linkage, IIndexFileLocation location,
+			ISignificantMacros macroDictionary) throws CoreException {
+		return PDOMFile.findFile(linkage, getFileIndex(), location, locationConverter, macroDictionary);
+	}
+
+	public IIndexFragmentFile[] getFiles(int linkageID, IIndexFileLocation location) throws CoreException {
+		PDOMLinkage linkage= getLinkage(linkageID);
+		if (linkage == null)
+			return IIndexFragmentFile.EMPTY_ARRAY;
+		return PDOMFile.findFiles(linkage, getFileIndex(), location, locationConverter);
 	}
 
 	public IIndexFragmentFile[] getFiles(IIndexFileLocation location) throws CoreException {
@@ -436,7 +456,7 @@ public class PDOM extends PlatformObject implements IPDOM {
 
 	public IIndexFragmentFile[] getAllFiles() throws CoreException {
 		final List<PDOMFile> locations = new ArrayList<PDOMFile>();
-		getFileIndex().accept(new IBTreeVisitor(){
+		getFileIndex().accept(new IBTreeVisitor() {
 			public int compare(long record) throws CoreException {
 				return 0;
 			}
@@ -449,11 +469,12 @@ public class PDOM extends PlatformObject implements IPDOM {
 		return locations.toArray(new IIndexFragmentFile[locations.size()]);
 	}
 
-	protected IIndexFragmentFile addFile(int linkageID, IIndexFileLocation location) throws CoreException {
+	protected IIndexFragmentFile addFile(int linkageID, IIndexFileLocation location,
+			ISignificantMacros sigMacros) throws CoreException {
 		PDOMLinkage linkage= createLinkage(linkageID);
-		IIndexFragmentFile file = getFile(linkage, location);
+		IIndexFragmentFile file = getFile(linkage, location, sigMacros);
 		if (file == null) {
-			PDOMFile pdomFile = new PDOMFile(linkage, location, linkageID);
+			PDOMFile pdomFile = new PDOMFile(linkage, location, linkageID, sigMacros);
 			getFileIndex().insert(pdomFile.getRecord());
 			file= pdomFile;
 			fEvent.setHasNewFiles();
@@ -1077,7 +1098,7 @@ public class PDOM extends PlatformObject implements IPDOM {
 			return (PDOMFile) file;
 		}
 
-		return getFile(file.getLinkageID(), file.getLocation());
+		return getFile(file.getLinkageID(), file.getLocation(), file.getSignificantMacros());
 	}
 
 	public File getPath() {
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMFileSet.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMFileSet.java
index bf00566c876..fa836eda9fb 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMFileSet.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMFileSet.java
@@ -28,6 +28,11 @@ public class PDOMFileSet implements IIndexFragmentFileSet {
 		fFileIDs.add(pdomFile.getRecord());
 	}
 
+	public void remove(IIndexFragmentFile fragFile) {
+		PDOMFile pdomFile= (PDOMFile) fragFile;
+		fFileIDs.remove(pdomFile.getRecord());
+	}
+
 	public boolean containsFileOfLocalBinding(IIndexFragmentBinding fb) throws CoreException {
 		PDOMBinding pdomBinding= (PDOMBinding) fb;
 		return fFileIDs.contains(pdomBinding.getLocalToFileRec());
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMManager.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMManager.java
index e9d85a73bd2..16abe010082 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMManager.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMManager.java
@@ -1091,12 +1091,14 @@ public class PDOMManager implements IWritableIndexManager, IListener {
 		assert monitor != null;
 		Thread th= null;
 		if (waitMaxMillis != FOREVER) {
+			final Thread callingThread= Thread.currentThread();
 			th= new Thread() {
 				@Override
 				public void run() {
 					try {
 						Thread.sleep(waitMaxMillis);
 						monitor.setCanceled(true);
+						callingThread.interrupt();
 					} catch (InterruptedException e) {
 					}
 				}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMProxy.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMProxy.java
index f7684b13de8..0604bc2e191 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMProxy.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMProxy.java
@@ -24,6 +24,7 @@ import org.eclipse.cdt.core.index.IIndexFileLocation;
 import org.eclipse.cdt.core.index.IIndexLinkage;
 import org.eclipse.cdt.core.index.IIndexMacro;
 import org.eclipse.cdt.core.index.IndexFilter;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.internal.core.index.IIndexFragmentBinding;
 import org.eclipse.cdt.internal.core.index.IIndexFragmentFile;
 import org.eclipse.cdt.internal.core.index.IIndexFragmentFileSet;
@@ -53,6 +54,7 @@ public class PDOMProxy implements IPDOM {
 			fLockDebugging= new HashMap<Thread, DebugLockInfo>();
 		}
 	}
+
 	public synchronized void acquireReadLock() throws InterruptedException {
 		if (fDelegate != null) {
 			fDelegate.acquireReadLock();
@@ -152,6 +154,7 @@ public class PDOMProxy implements IPDOM {
 		return 0;
 	}
 
+	@Deprecated
 	public synchronized IIndexFragmentFile getFile(int linkageID, IIndexFileLocation location) throws CoreException {
 		if (fDelegate != null)
 			return fDelegate.getFile(linkageID, location);
@@ -159,6 +162,22 @@ public class PDOMProxy implements IPDOM {
 		return null;
 	}
 
+	public IIndexFragmentFile getFile(int linkageID, IIndexFileLocation location,
+			ISignificantMacros sigMacros) throws CoreException {
+		if (fDelegate != null)
+			return fDelegate.getFile(linkageID, location, sigMacros);
+
+		return null;
+	}
+
+	public IIndexFragmentFile[] getFiles(int linkageID, IIndexFileLocation location)
+			throws CoreException {
+		if (fDelegate != null)
+			return fDelegate.getFiles(linkageID, location);
+
+		return IIndexFragmentFile.EMPTY_ARRAY;
+	}
+
 	public synchronized IIndexFragmentFile[] getFiles(IIndexFileLocation location) throws CoreException {
 		if (fDelegate != null)
 			return fDelegate.getFiles(location);
@@ -289,10 +308,12 @@ public class PDOMProxy implements IPDOM {
 	public Object putCachedResult(Object key, Object value, boolean replace) {
 		return value;
 	}
+
 	public void clearResultCache() {
 		if (fDelegate != null)
 			fDelegate.clearResultCache();
 	}
+
 	/* (non-Javadoc)
 	 * @see org.eclipse.cdt.internal.core.index.IIndexFragment#getInlineNamespaces()
 	 */
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMWriter.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMWriter.java
index b435461ca37..7bf753147d3 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMWriter.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMWriter.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2007, 2010 Wind River Systems, Inc. and others.
+ * Copyright (c) 2007, 2011 Wind River Systems, Inc. and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -13,8 +13,6 @@
 package org.eclipse.cdt.internal.core.pdom;
 
 import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -47,11 +45,14 @@ import org.eclipse.cdt.core.dom.ast.cpp.ICPPFunctionTemplate;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPNamespace;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPNamespaceAlias;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPTemplateParameter;
+import org.eclipse.cdt.core.index.IIndexFile;
 import org.eclipse.cdt.core.index.IIndexFileLocation;
 import org.eclipse.cdt.core.index.IIndexInclude;
 import org.eclipse.cdt.core.parser.IProblem;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.internal.core.dom.parser.ASTInternal;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.ICPPUnknownBinding;
+import org.eclipse.cdt.internal.core.index.FileContentKey;
 import org.eclipse.cdt.internal.core.index.IIndexFragmentFile;
 import org.eclipse.cdt.internal.core.index.IWritableIndex;
 import org.eclipse.cdt.internal.core.index.IWritableIndex.IncludeInformation;
@@ -70,6 +71,36 @@ import org.eclipse.osgi.util.NLS;
  * @since 4.0
  */
 abstract public class PDOMWriter {
+	public static class FileInAST {
+		final IASTPreprocessorIncludeStatement fIncludeStatement;
+		final FileContentKey fFileContentKey;
+		final long fContentsHash;
+
+		public FileInAST(IASTPreprocessorIncludeStatement includeStmt, FileContentKey key, long contentsHash) {
+			fIncludeStatement= includeStmt;
+			fFileContentKey= key;
+			fContentsHash= contentsHash;
+		}
+		
+		@Override
+		public String toString() {
+			return fFileContentKey.toString();
+		}
+	}
+	
+	public static class FileContext {
+		final IIndexFragmentFile fContext;
+		final IIndexFragmentFile fOldFile;
+		IIndexFragmentFile fNewFile;
+		public boolean fLostPragmaOnceSemantics;
+		
+		public FileContext(IIndexFragmentFile context, IIndexFragmentFile oldFile) {
+			fContext= context;
+			fOldFile= oldFile;
+			fNewFile= null;
+		}
+	}
+
 	public static int SKIP_ALL_REFERENCES= -1;
 	public static int SKIP_TYPE_REFERENCES= 1;
 	public static int SKIP_MACRO_REFERENCES= 2;
@@ -77,9 +108,24 @@ abstract public class PDOMWriter {
 	public static int SKIP_NO_REFERENCES= 0;
 
 	private static class Symbols {
-		ArrayList<IASTName[]> fNames= new ArrayList<IASTName[]>();
-		ArrayList<IASTPreprocessorStatement> fMacros= new ArrayList<IASTPreprocessorStatement>();
-		ArrayList<IASTPreprocessorIncludeStatement> fIncludes= new ArrayList<IASTPreprocessorIncludeStatement>();
+		final ArrayList<IASTName[]> fNames= new ArrayList<IASTName[]>();
+		final ArrayList<IASTPreprocessorStatement> fMacros= new ArrayList<IASTPreprocessorStatement>();
+		final ArrayList<IASTPreprocessorIncludeStatement> fIncludes= new ArrayList<IASTPreprocessorIncludeStatement>();
+	}
+	
+	private static class Data {
+		final IASTTranslationUnit fAST;
+		final FileInAST[] fSelectedFiles;
+		final IWritableIndex fIndex;
+		final Map<IASTPreprocessorIncludeStatement, Symbols> fSymbolMap = new HashMap<IASTPreprocessorIncludeStatement, Symbols>();
+		final Set<IASTPreprocessorIncludeStatement> fContextIncludes = new HashSet<IASTPreprocessorIncludeStatement>();
+		final List<IStatus> fStati= new ArrayList<IStatus>();
+		
+		public Data(IASTTranslationUnit ast, FileInAST[] selectedFiles, IWritableIndex index) {
+			fAST= ast;
+			fSelectedFiles= selectedFiles;
+			fIndex= index;
+		}
 	}
 
 	private boolean fShowProblems;
@@ -90,7 +136,6 @@ abstract public class PDOMWriter {
 	protected final IndexerStatistics fStatistics;
 	protected final IndexerInputAdapter fResolver;
 
-	private IndexerProgress fInfo= new IndexerProgress();
 	private int fSkipReferences= SKIP_NO_REFERENCES;
 
 	public PDOMWriter(IndexerInputAdapter resolver) {
@@ -140,39 +185,45 @@ abstract public class PDOMWriter {
 	 * 
 	 * When flushIndex is set to <code>false</code>, you must make sure to flush 
 	 * the index after your last write operation.
-	 * @since 4.0
 	 */
-	public void addSymbols(IASTTranslationUnit ast, IIndexFileLocation[] ifls, IWritableIndex index,
-			int readlockCount, boolean flushIndex, long fileContentsHash, int configHash,
-			ITodoTaskUpdater taskUpdater, IProgressMonitor pm) throws InterruptedException, CoreException {
+	final protected void addSymbols(IASTTranslationUnit ast, FileInAST[] selectedFiles,
+			IWritableIndex index, boolean flushIndex, FileContext ctx,
+			ITodoTaskUpdater taskUpdater, IProgressMonitor pm) throws InterruptedException,
+			CoreException {
 		if (fShowProblems) {
 			fShowInclusionProblems= true;
 			fShowScannerProblems= true;
 			fShowSyntaxProblems= true;
 		}
-		final Map<IIndexFileLocation, Symbols> symbolMap= new HashMap<IIndexFileLocation, Symbols>();
-		for (IIndexFileLocation ifl : ifls) {
-			prepareInMap(symbolMap, ifl);
+		
+		Data data= new Data(ast, selectedFiles, index);
+		for (FileInAST file : selectedFiles) {
+			data.fSymbolMap.put(file.fIncludeStatement, new Symbols());
 		}
-		ArrayList<IStatus> stati= new ArrayList<IStatus>();
+		
 
-		HashSet<IASTPreprocessorIncludeStatement> contextIncludes= new HashSet<IASTPreprocessorIncludeStatement>();
-		extractSymbols(ast, symbolMap, contextIncludes);
+		// Extract symbols from AST
+		extractSymbols(data);
 
-		// name resolution
-		resolveNames(symbolMap, ifls, stati, pm);
+		// Name resolution
+		resolveNames(data, pm);
 
-		// index update
-		storeSymbolsInIndex(symbolMap, ifls, ast.getLinkage().getLinkageID(), fileContentsHash,
-				configHash, contextIncludes, index, readlockCount, flushIndex, stati, pm);
+		// Index update
+		storeSymbolsInIndex(data, ctx, flushIndex, pm);
 
+		// Tasks update
 		if (taskUpdater != null) {
-			taskUpdater.updateTasks(ast.getComments(), ifls);
+			Set<IIndexFileLocation> locations= new HashSet<IIndexFileLocation>();
+			for (FileInAST file : selectedFiles) {
+				locations.add(file.fFileContentKey.getLocation());
+			}
+			taskUpdater.updateTasks(ast.getComments(), locations.toArray(new IIndexFileLocation[locations.size()]));
 		}
-		if (!stati.isEmpty()) {
+		if (!data.fStati.isEmpty()) {
+			List<IStatus> stati = data.fStati;
 			String path= null;
-			if (ifls.length > 0) {
-				path= ifls[ifls.length - 1].getURI().getPath();
+			if (selectedFiles.length > 0) {
+				path= selectedFiles[selectedFiles.length - 1].fFileContentKey.getLocation().getURI().getPath();
 			} else {
 				path= ast.getFilePath().toString();
 			}
@@ -190,60 +241,73 @@ abstract public class PDOMWriter {
 		}
 	}
 
-	private void storeSymbolsInIndex(final Map<IIndexFileLocation, Symbols> symbolMap, IIndexFileLocation[] ifls,
-			int linkageID, long fileContentsHash, int configHash,
-			HashSet<IASTPreprocessorIncludeStatement> contextIncludes, IWritableIndex index, int readlockCount,
-			boolean flushIndex, ArrayList<IStatus> stati, IProgressMonitor pm)
+	private void storeSymbolsInIndex(final Data data, FileContext ctx, boolean flushIndex, IProgressMonitor pm)
 			throws InterruptedException, CoreException {
-		for (int i= 0; i < ifls.length; i++) {
+		final IIndexFragmentFile newFile= ctx == null ? null : ctx.fNewFile;
+		final int linkageID= data.fAST.getLinkage().getLinkageID();
+		for (int i= 0; i < data.fSelectedFiles.length; i++) {
 			if (pm.isCanceled())
 				return;
 
-			final IIndexFileLocation ifl= ifls[i];
-			if (ifl != null) {
+			final FileInAST fileInAST= data.fSelectedFiles[i];
+			if (fileInAST != null) {
 				if (fShowActivity) {
-					trace("Indexer: adding " + ifl.getURI());  //$NON-NLS-1$
+					trace("Indexer: adding " + fileInAST.fFileContentKey.getLocation().getURI());  //$NON-NLS-1$
 				}
 				Throwable th= null;
-				YieldableIndexLock lock = new YieldableIndexLock(index, readlockCount, flushIndex);
+				YieldableIndexLock lock = new YieldableIndexLock(data.fIndex, flushIndex);
 				lock.acquire();
 				try {
-					storeFileInIndex(index, ifl, symbolMap, linkageID, fileContentsHash, configHash,
-							contextIncludes, lock);
-				} catch (RuntimeException e) {
+					final boolean isReplacement= ctx != null && fileInAST.fIncludeStatement == null;
+					IIndexFragmentFile ifile= null;
+					if (!isReplacement || newFile == null) {
+						ifile= storeFileInIndex(data, fileInAST, linkageID, lock);
+						reportFileWrittenToIndex(fileInAST, ifile);
+					} 
+					
+					if (isReplacement) {
+						if (ifile == null)
+							ifile= newFile;
+						if (ctx != null && !ctx.fOldFile.equals(ifile) && ifile != null) {
+							if (ctx.fOldFile.hasPragmaOnceSemantics() &&
+									!ifile.hasPragmaOnceSemantics()) {
+								data.fIndex.transferContext(ctx.fOldFile, ifile);
+								ctx.fLostPragmaOnceSemantics= true;
+							} else {
+								data.fIndex.transferIncluders(ctx.fOldFile, ifile);
+							}
+						}
+					} 
+					} catch (RuntimeException e) {
 					th= e;
 				} catch (StackOverflowError e) {
 					th= e;
 				} catch (AssertionError e) {
 					th= e;
 				} finally {
-					// When the caller holds a read-lock, the result cache of the index is never cleared.
+					// Because the caller holds a read-lock, the result cache of the index is never cleared.
 					// ==> Before releasing the lock for the last time in this ast, we clear the result cache.
-					if (readlockCount > 0  && i == ifls.length-1) {
-						index.clearResultCache();
+					if (i == data.fSelectedFiles.length-1) {
+						data.fIndex.clearResultCache();
 					}
 					lock.release();
 				}
 				if (th != null) {
-					stati.add(createStatus(NLS.bind(Messages.PDOMWriter_errorWhileParsing,
-							ifl.getURI().getPath()), th));
-				}
-				if (i < ifls.length - 1) {
-					updateFileCount(0, 0, 1); // update header count
+					data.fStati.add(createStatus(NLS.bind(Messages.PDOMWriter_errorWhileParsing,
+							fileInAST.fFileContentKey.getLocation().getURI().getPath()), th));
 				}
 				fStatistics.fAddToIndexTime += lock.getCumulativeLockTime();
 			}
 		}
 	}
 
-	private void resolveNames(final Map<IIndexFileLocation, Symbols> symbolMap, IIndexFileLocation[] ifls,
-			ArrayList<IStatus> stati, IProgressMonitor pm) {
+	private void resolveNames(Data data, IProgressMonitor pm) {
 		long start= System.currentTimeMillis();
-		for (IIndexFileLocation path : ifls) {
+		for (FileInAST file : data.fSelectedFiles) {
 			if (pm.isCanceled()) {
 				return;
 			}
-			Symbols symbols= symbolMap.get(path);
+			Symbols symbols= data.fSymbolMap.get(file.fIncludeStatement);
 
 			final ArrayList<IASTName[]> names= symbols.fNames;
 			boolean reported= false;
@@ -286,8 +350,8 @@ abstract public class PDOMWriter {
 					}
 					if (th != null) {
 						if (!reported) {
-							stati.add(CCorePlugin.createStatus(NLS.bind(Messages.PDOMWriter_errorResolvingName,
-									name.toString(), path.getURI().getPath()), th));
+							data.fStati.add(CCorePlugin.createStatus(NLS.bind(Messages.PDOMWriter_errorResolvingName,
+									name.toString(), file.fFileContentKey.getLocation().getURI().getPath()), th));
 						}
 						reported= true;
 						j.remove();
@@ -298,45 +362,44 @@ abstract public class PDOMWriter {
 		fStatistics.fResolutionTime += System.currentTimeMillis()-start;
 	}
 
-	private void extractSymbols(IASTTranslationUnit ast, final Map<IIndexFileLocation, Symbols> symbolMap,
-			Collection<IASTPreprocessorIncludeStatement> contextIncludes) throws CoreException {
-		final HashSet<IIndexFileLocation> contextIFLs= new HashSet<IIndexFileLocation>();
-		final IIndexFileLocation astIFL = fResolver.resolveASTPath(ast.getFilePath());
-
+	private void extractSymbols(Data data) throws CoreException {
 		int unresolvedIncludes= 0;
+		final IASTTranslationUnit ast = data.fAST;
+		final Map<IASTPreprocessorIncludeStatement, Symbols> symbolMap = data.fSymbolMap;
+
 		IASTPreprocessorStatement[] stmts = ast.getAllPreprocessorStatements();
 		for (final IASTPreprocessorStatement stmt : stmts) {
-			// includes
+			// Includes.
 			if (stmt instanceof IASTPreprocessorIncludeStatement) {
 				IASTPreprocessorIncludeStatement include= (IASTPreprocessorIncludeStatement) stmt;
 
 				final IASTFileLocation astLoc= include.getFileLocation();
-				final IIndexFileLocation sourceIFL= astLoc != null ? fResolver.resolveASTPath(astLoc.getFileName()) : astIFL; // command-line includes
-				final boolean updateSource= symbolMap.containsKey(sourceIFL);
+				IASTPreprocessorIncludeStatement owner = astLoc.getContextInclusionStatement();
+				final boolean updateSource= symbolMap.containsKey(owner);
 				if (updateSource) {
-					addToMap(symbolMap, sourceIFL, include);
+					addToMap(symbolMap, owner, include);
 				}
 				if (include.isActive()) {
 					if (!include.isResolved()) {
 						unresolvedIncludes++;
 					} else if (updateSource) {
-						// the include was parsed, check if we want to update the included file in the index
-						final IIndexFileLocation targetIFL= fResolver.resolveASTPath(include.getPath());
-						if (symbolMap.containsKey(targetIFL) && contextIFLs.add(targetIFL)) {
-							contextIncludes.add(include);
+						// The include was parsed, check if we want to update the included file in the index.
+						if (symbolMap.containsKey(include)) {
+							data.fContextIncludes.add(include);
 						}
 					}
 				}
-			} else if (stmt.isActive() && (stmt instanceof IASTPreprocessorUndefStatement || stmt instanceof IASTPreprocessorMacroDefinition)) {
+			} else if (stmt.isActive() &&
+					(stmt instanceof IASTPreprocessorUndefStatement || stmt instanceof IASTPreprocessorMacroDefinition)) {
 				IASTFileLocation sourceLoc = stmt.getFileLocation();
 				if (sourceLoc != null) { // skip built-ins and command line macros
-					IIndexFileLocation path2 = fResolver.resolveASTPath(sourceLoc.getFileName());
-					addToMap(symbolMap, path2, stmt);
+					IASTPreprocessorIncludeStatement owner = sourceLoc.getContextInclusionStatement();
+					addToMap(symbolMap, owner, stmt);
 				}
 			}
 		}
 
-		// names
+		// Names.
 		final IndexerASTVisitor visitor = new IndexerASTVisitor((fSkipReferences & SKIP_IMPLICIT_REFERENCES) == 0) {
 			@Override
 			public void visit(IASTName name, IASTName caller) {
@@ -348,13 +411,13 @@ abstract public class PDOMWriter {
 					}
 				}
 
-				// assign a location to anonymous types.
+				// Assign a location to anonymous types.
 				name= PDOMASTAdapter.getAdapterIfAnonymous(name);
 				if (name != null) {
 					IASTFileLocation nameLoc = name.getFileLocation();
 					if (nameLoc != null) {
-						IIndexFileLocation location = fResolver.resolveASTPath(nameLoc.getFileName());
-						addToMap(symbolMap, location, new IASTName[]{name, caller});
+						IASTPreprocessorIncludeStatement owner= nameLoc.getContextInclusionStatement();
+						addToMap(symbolMap, owner, new IASTName[] { name, caller });
 					}
 				}
 			}
@@ -368,8 +431,8 @@ abstract public class PDOMWriter {
 				for (IASTName name : refs) {
 					IASTFileLocation nameLoc = name.getFileLocation();
 					if (nameLoc != null) {
-						IIndexFileLocation location = fResolver.resolveASTPath(nameLoc.getFileName());
-						addToMap(symbolMap, location, new IASTName[]{name, null});
+						IASTPreprocessorIncludeStatement owner= nameLoc.getContextInclusionStatement();
+						addToMap(symbolMap, owner, new IASTName[] { name, null });
 					}
 				}
 			}
@@ -426,57 +489,45 @@ abstract public class PDOMWriter {
 		return false;
 	}
 
-	private void addToMap(Map<IIndexFileLocation, Symbols> map, IIndexFileLocation location, IASTName[] thing) {
-		Symbols lists= map.get(location);
+	private void addToMap(Map<IASTPreprocessorIncludeStatement, Symbols> symbolMap, IASTPreprocessorIncludeStatement owner, IASTName[] thing) {
+		Symbols lists= symbolMap.get(owner);
 		if (lists != null)
 			lists.fNames.add(thing);
 	}
 
-	private void addToMap(Map<IIndexFileLocation, Symbols> map, IIndexFileLocation location,
-			IASTPreprocessorIncludeStatement thing) {
-		Symbols lists= map.get(location);
+	private void addToMap(Map<IASTPreprocessorIncludeStatement, Symbols> symbolMap, IASTPreprocessorIncludeStatement owner, IASTPreprocessorIncludeStatement thing) {
+		Symbols lists= symbolMap.get(owner);
 		if (lists != null)
 			lists.fIncludes.add(thing);
 	}
 
-	private void addToMap(Map<IIndexFileLocation, Symbols> map, IIndexFileLocation location,
-			IASTPreprocessorStatement thing) {
-		Symbols lists= map.get(location);
+	private void addToMap(Map<IASTPreprocessorIncludeStatement, Symbols> symbolMap,
+			IASTPreprocessorIncludeStatement owner, IASTPreprocessorStatement thing) {
+		Symbols lists= symbolMap.get(owner);
 		if (lists != null)
 			lists.fMacros.add(thing);
 	}
 
-	private boolean prepareInMap(Map<IIndexFileLocation, Symbols> map, IIndexFileLocation location) {
-		if (map.get(location) == null) {
-			map.put(location, new Symbols());
-		}
-		return false;
-	}
-
-	private IIndexFragmentFile storeFileInIndex(IWritableIndex index, IIndexFileLocation location,
-			Map<IIndexFileLocation, Symbols> symbolMap, int linkageID, long fileContentsHash,
-			int configHash, Set<IASTPreprocessorIncludeStatement> contextIncludes,
+	private IIndexFragmentFile storeFileInIndex(Data data, FileInAST astFile, int linkageID,
 			YieldableIndexLock lock) throws CoreException, InterruptedException {
-		Set<IIndexFileLocation> clearedContexts= Collections.emptySet();
+		final IWritableIndex index = data.fIndex;
 		IIndexFragmentFile file;
-		// We create a temporary PDOMFile with zero timestamp, add names to it, then replace contents
-		// of the old file from the temporary one, then delete the temporary file. The write lock on
-		// the index can be yielded between adding names to the temporary file, if another thread
-		// is waiting for a read lock.
-		IIndexFragmentFile oldFile = index.getWritableFile(linkageID, location);
-		if (oldFile != null) {
-			IIndexInclude[] includedBy = index.findIncludedBy(oldFile);
-			if (includedBy.length > 0) {
-				clearedContexts= new HashSet<IIndexFileLocation>();
-				for (IIndexInclude include : includedBy) {
-					clearedContexts.add(include.getIncludedByLocation());
-				}
-			}
-		}
-		file= index.addUncommittedFile(linkageID, location);
+		// We create a temporary PDOMFile with zero timestamp, add names to it, then replace
+		// contents of the old file from the temporary one, then delete the temporary file.
+		// The write lock on the index can be yielded between adding names to the temporary file,
+		// if another thread is waiting for a read lock.
+		final FileContentKey fileKey = astFile.fFileContentKey;
+		final IASTPreprocessorIncludeStatement owner= astFile.fIncludeStatement;
+		
+		IIndexFileLocation location = fileKey.getLocation();
+		ISignificantMacros significantMacros = fileKey.getSignificantMacros();
+		IIndexFragmentFile oldFile = index.getWritableFile(linkageID, location, significantMacros);
+		file= index.addUncommittedFile(linkageID, location, significantMacros);
 		try {
-			file.setScannerConfigurationHashcode(configHash);
-			Symbols lists= symbolMap.get(location);
+			boolean pragmaOnce= owner != null ? owner.hasPragmaOnceSemantics() : data.fAST.hasPragmaOnceSemantics(); 
+			file.setPragmaOnceSemantics(pragmaOnce);
+
+			Symbols lists= data.fSymbolMap.get(owner);
 			if (lists != null) {
 				IASTPreprocessorStatement[] macros= lists.fMacros.toArray(new IASTPreprocessorStatement[lists.fMacros.size()]);
 				IASTName[][] names= lists.fNames.toArray(new IASTName[lists.fNames.size()][]);
@@ -487,22 +538,30 @@ abstract public class PDOMWriter {
 					}
 				}
 
-				IncludeInformation[] includeInfos= new IncludeInformation[lists.fIncludes.size()];
+				List<IncludeInformation> includeInfos= new ArrayList<IncludeInformation>();
 				for (int i= 0; i < lists.fIncludes.size(); i++) {
-					final IASTPreprocessorIncludeStatement include = lists.fIncludes.get(i);
-					final IncludeInformation info= includeInfos[i]= new IncludeInformation();
-					info.fStatement= include;
-					if (include.isResolved()) {
-						info.fLocation= fResolver.resolveASTPath(include.getPath());
-						info.fIsContext= include.isActive() &&
-							(contextIncludes.contains(include) || clearedContexts.contains(info.fLocation));
+					final IASTPreprocessorIncludeStatement stmt = lists.fIncludes.get(i);
+					if (!stmt.isResolved()) {
+						includeInfos.add(new IncludeInformation(stmt, null, ISignificantMacros.NONE, false));
+					} else {
+						IIndexFileLocation targetLoc = fResolver.resolveASTPath(stmt.getPath());
+						ISignificantMacros mainSig= stmt.getSignificantMacros();
+						for (ISignificantMacros sig : stmt.getLoadedVersions()) {
+							if (!sig.equals(mainSig)) {
+								includeInfos.add(new IncludeInformation(stmt, targetLoc, sig, false));
+							}
+						}
+						final boolean isContext = stmt.isActive() && stmt.isResolved() && 
+								(data.fContextIncludes.contains(stmt) || isContextFor(oldFile, stmt));
+						includeInfos.add(new IncludeInformation(stmt, targetLoc, mainSig, isContext));
 					}
 				}
-				index.setFileContent(file, linkageID, includeInfos, macros, names, fResolver, lock);
+				IncludeInformation[] includeInfoArray= includeInfos.toArray(new IncludeInformation[includeInfos.size()]);
+				index.setFileContent(file, linkageID, includeInfoArray, macros, names, fResolver, lock);
 			}
 			file.setTimestamp(fResolver.getLastModified(location));
 			file.setEncodingHashcode(fResolver.getEncoding(location).hashCode());
-			file.setContentsHash(fileContentsHash);
+			file.setContentsHash(astFile.fContentsHash);
 			file = index.commitUncommittedFile();
 		} finally {
 			index.clearUncommittedFile();
@@ -510,35 +569,21 @@ abstract public class PDOMWriter {
 		return file;
 	}
 
-	/**
-	 * Makes a copy of the current progress information and returns it.
-	 * @since 4.0
-	 */
-	public IndexerProgress getProgressInformation() {
-		synchronized (fInfo) {
-			return new IndexerProgress(fInfo);
-		}
-	}
-
-	/**
-	 * Updates current progress information with the provided delta.
-	 */
-	protected final void updateFileCount(int sources, int primaryHeader, int header) {
-		synchronized (fInfo) {
-			fInfo.fCompletedSources += sources;
-			fInfo.fPrimaryHeaderCount += primaryHeader;
-			fInfo.fCompletedHeaders += header;
+	private boolean isContextFor(IIndexFragmentFile oldFile, IASTPreprocessorIncludeStatement stmt)
+			throws CoreException {
+		IIndexFile target= stmt.getImportedIndexFile();
+		if (oldFile != null && target != null) {
+			IIndexInclude ctxInclude = target.getParsedInContext();
+			if (ctxInclude != null && oldFile.equals(ctxInclude.getIncludedBy()))
+				return true;
 		}
+		return false;
 	}
 
 	/**
-	 * Updates current progress information with the provided delta.
+	 * Informs the subclass that a file has been stored in the index.
 	 */
-	protected final void incrementRequestedFilesCount(int delta) {
-		synchronized (fInfo) {
-			fInfo.fRequestedFilesCount += delta;
-		}
-	}
+	protected abstract void reportFileWrittenToIndex(FileInAST file, IIndexFragmentFile iFile) throws CoreException;
 
 	private String getLocationInfo(String filename, int lineNumber) {
 		return " at " + filename + "(" + lineNumber + ")"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/TeamPDOMImportOperation.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/TeamPDOMImportOperation.java
index 65c286d4943..a339445fa7d 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/TeamPDOMImportOperation.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/TeamPDOMImportOperation.java
@@ -264,7 +264,7 @@ public class TeamPDOMImportOperation implements IWorkspaceRunnable {
 			for (IIndexFragmentFile ifile : filesToDelete) {
 				if (ifile != null) {
 					checkMonitor(monitor);
-					pdom.clearFile(ifile, null);
+					pdom.clearFile(ifile);
 				}
 			}
 			for (FileAndChecksum fc : updateTimestamps) {
@@ -275,7 +275,6 @@ public class TeamPDOMImportOperation implements IWorkspaceRunnable {
 					IResource r= fc.fFile.getResource();
 					if (r != null) {
 						file.setTimestamp(r.getLocalTimeStamp());
-						file.setScannerConfigurationHashcode(0);
 					}
 				}
 			}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/WritablePDOM.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/WritablePDOM.java
index 8de0cb7e20d..aa42326413f 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/WritablePDOM.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/WritablePDOM.java
@@ -1,32 +1,36 @@
 /*******************************************************************************
- * Copyright (c) 2006, 2010 Wind River Systems, Inc. and others.
+ * Copyright (c) 2006, 2011 Wind River Systems, Inc. and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
- *    Markus Schorn - initial API and implementation
- *    Andrew Ferguson (Symbian)
- *    Sergey Prigogin (Google)
+ *     Markus Schorn - initial API and implementation
+ *     Andrew Ferguson (Symbian)
+ *     Sergey Prigogin (Google)
  *******************************************************************************/ 
 package org.eclipse.cdt.internal.core.pdom;
 
 import java.io.File;
 import java.util.ArrayList;
-import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
+import org.eclipse.cdt.core.dom.ast.IASTFileLocation;
 import org.eclipse.cdt.core.dom.ast.IASTName;
+import org.eclipse.cdt.core.dom.ast.IASTNode;
+import org.eclipse.cdt.core.dom.ast.IASTPreprocessorIncludeStatement;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorStatement;
+import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit;
 import org.eclipse.cdt.core.index.IIndexFileLocation;
 import org.eclipse.cdt.core.index.IIndexLocationConverter;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
+import org.eclipse.cdt.internal.core.index.FileContentKey;
 import org.eclipse.cdt.internal.core.index.IIndexFragment;
 import org.eclipse.cdt.internal.core.index.IIndexFragmentFile;
-import org.eclipse.cdt.internal.core.index.IWritableIndexFragment;
 import org.eclipse.cdt.internal.core.index.IWritableIndex.IncludeInformation;
-import org.eclipse.cdt.internal.core.pdom.db.BTree;
+import org.eclipse.cdt.internal.core.index.IWritableIndexFragment;
 import org.eclipse.cdt.internal.core.pdom.db.ChunkCache;
 import org.eclipse.cdt.internal.core.pdom.db.DBProperties;
 import org.eclipse.cdt.internal.core.pdom.db.IBTreeVisitor;
@@ -45,7 +49,7 @@ public class WritablePDOM extends PDOM implements IWritableIndexFragment {
 	private ASTFilePathResolver fPathResolver;
 	private PDOMFile fileBeingUpdated;
 	private PDOMFile uncommittedFile;
-	private IIndexFileLocation uncommittedLocation;
+	private FileContentKey uncommittedKey;
 
 	public WritablePDOM(File dbPath, IIndexLocationConverter locationConverter,
 			Map<String, IPDOMLinkageFactory> linkageFactoryMappings) throws CoreException {
@@ -62,50 +66,50 @@ public class WritablePDOM extends PDOM implements IWritableIndexFragment {
 	}
 
 	@Override
-	public IIndexFragmentFile addFile(int linkageID, IIndexFileLocation location) throws CoreException {
-		if (uncommittedLocation != null && uncommittedLocation.equals(location)) {
+	public IIndexFragmentFile addFile(int linkageID, IIndexFileLocation location, ISignificantMacros sigMacros) throws CoreException {
+		if (uncommittedKey != null && uncommittedKey.equals(new FileContentKey(linkageID, location, sigMacros)))
 			return uncommittedFile;
-		}
-		return super.addFile(linkageID, location);
+		
+		return super.addFile(linkageID, location, sigMacros);
 	}
 
-	public IIndexFragmentFile addUncommittedFile(int linkageID, IIndexFileLocation location) throws CoreException {
-		uncommittedLocation = location;
-		fileBeingUpdated = getFile(linkageID, uncommittedLocation);
+	public IIndexFragmentFile addUncommittedFile(int linkageID, IIndexFileLocation location,
+			ISignificantMacros significantMacros) throws CoreException {
+		uncommittedKey = new FileContentKey(linkageID, location, significantMacros);
+		fileBeingUpdated = getFile(linkageID, location, significantMacros);
 		PDOMLinkage linkage= createLinkage(linkageID);
-		uncommittedFile = new PDOMFile(linkage, location, linkageID);
+		uncommittedFile = new PDOMFile(linkage, location, linkageID, significantMacros);
 		return uncommittedFile;
 	}
 
 	public IIndexFragmentFile commitUncommittedFile() throws CoreException {
 		if (uncommittedFile == null)
 			return null;
-		IIndexFragmentFile file;
+		PDOMFile file;
 		if (fileBeingUpdated == null) {
-			// New file.
-			BTree fileIndex = getFileIndex();
-			fileIndex.insert(uncommittedFile.getRecord());
+			// New file, insert it into the index.
 			file = uncommittedFile;
+			getFileIndex().insert(file.getRecord()); 
 		} else {
 			// Existing file.
 			fileBeingUpdated.replaceContentsFrom(uncommittedFile);
 			file = fileBeingUpdated;
 			fileBeingUpdated = null;
 		}
-		fEvent.fFilesWritten.add(uncommittedLocation);
+		fEvent.fFilesWritten.add(uncommittedKey.getLocation());
 		uncommittedFile = null;
-		uncommittedLocation = null;
+		uncommittedKey = null;
 		return file;
 	}
 
 	public void clearUncommittedFile() throws CoreException {
 		if (uncommittedFile != null) {
 			try {
-				uncommittedFile.clear(null);
+				uncommittedFile.clear();
 				uncommittedFile.delete();
 			} finally {
 				uncommittedFile = null;
-				uncommittedLocation = null;
+				uncommittedKey = null;
 				fileBeingUpdated = null;
 			}
 		}
@@ -117,7 +121,6 @@ public class WritablePDOM extends PDOM implements IWritableIndexFragment {
 		assert sourceFile.getIndexFragment() == this;
 		
 		PDOMFile pdomFile = (PDOMFile) sourceFile;
-		pdomFile.addIncludesTo(includes);
 		pdomFile.addMacros(macros);
 		final ASTFilePathResolver origResolver= fPathResolver;
 		fPathResolver= pathResolver;
@@ -126,6 +129,8 @@ public class WritablePDOM extends PDOM implements IWritableIndexFragment {
 		} finally {
 			fPathResolver= origResolver;
 		}
+		// Includes expose the temporary file in the index, we must not yield the lock beyond this point.
+		pdomFile.addIncludesTo(includes);
 		
 		final IIndexFileLocation location = pdomFile.getLocation();
 		if (location != null) {
@@ -134,12 +139,13 @@ public class WritablePDOM extends PDOM implements IWritableIndexFragment {
 		}
 	}
 
-	public void clearFile(IIndexFragmentFile file, Collection<IIndexFileLocation> contextsRemoved)
-			throws CoreException {
+	public void clearFile(IIndexFragmentFile file) throws CoreException {
 		assert file.getIndexFragment() == this;
-		((PDOMFile) file).clear(contextsRemoved);	
-		
-		fEvent.fClearedFiles.add(file.getLocation());
+		IIndexFileLocation location = file.getLocation();
+		PDOMFile pdomFile = (PDOMFile) file;
+		pdomFile.clear();	
+
+		fEvent.fClearedFiles.add(location);
 	}
 	
 	@Override
@@ -165,9 +171,9 @@ public class WritablePDOM extends PDOM implements IWritableIndexFragment {
 	}
 	
 	/**
-	 * Use the specified location converter to update each internal representation of a file location.
-	 * The file index is rebuilt with the new representations. Individual PDOMFile records are unmoved so
-	 * as to maintain referential integrity with other PDOM records.
+	 * Uses the specified location converter to update each internal representation of a file
+	 * location. The file index is rebuilt with the new representations. Individual PDOMFile records
+	 * are unmoved so as to maintain referential integrity with other PDOM records.
 	 * 
 	 * <b>A write-lock must be obtained before calling this method</b>
 	 * 
@@ -202,7 +208,7 @@ public class WritablePDOM extends PDOM implements IWritableIndexFragment {
 		// remove content where converter returns null
 		for (PDOMFile file : notConverted) {
 			file.convertIncludersToUnresolved();
-			file.clear(null);
+			file.clear();
 		}
 	}
 
@@ -227,16 +233,34 @@ public class WritablePDOM extends PDOM implements IWritableIndexFragment {
 		return false;
 	}
 
-	public PDOMFile getFileForASTPath(int linkageID, String astPath) throws CoreException {
-		if (fPathResolver != null && astPath != null) {
-			IIndexFileLocation location = fPathResolver.resolveASTPath(astPath);
-			if (location.equals(uncommittedLocation))
-				return fileBeingUpdated != null ? fileBeingUpdated : uncommittedFile;
-			return getFile(linkageID, location);
+	public PDOMFile getFileForASTNode(int linkageID, IASTNode node) throws CoreException {
+		if (fPathResolver != null && node != null) {
+			IASTFileLocation loc= node.getFileLocation();
+			if (loc != null) {
+				ISignificantMacros sigMacros= getSignificantMacros(node, loc);
+				if (sigMacros != null) {
+					IIndexFileLocation location = fPathResolver.resolveASTPath(loc.getFileName());
+					if (uncommittedKey != null && uncommittedKey.equals(new FileContentKey(linkageID, location, sigMacros)))
+						return fileBeingUpdated != null ? fileBeingUpdated : uncommittedFile;
+					return getFile(linkageID, location, sigMacros);
+				}
+			}
 		}
 		return null;
 	}
 
+	private ISignificantMacros getSignificantMacros(IASTNode node, IASTFileLocation loc) throws CoreException {
+		IASTPreprocessorIncludeStatement owner= loc.getContextInclusionStatement();
+		if (owner != null) 
+			return owner.getSignificantMacros();
+
+		IASTTranslationUnit tu = node.getTranslationUnit();
+		if (tu != null)
+			return tu.getSignificantMacros();
+		
+		return null;
+	}
+
 	@Override
 	public boolean hasLastingDefinition(PDOMBinding binding) throws CoreException {
 		if (fileBeingUpdated == null) {
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/YieldableIndexLock.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/YieldableIndexLock.java
index c96636f81dd..03015c012c4 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/YieldableIndexLock.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/YieldableIndexLock.java
@@ -19,14 +19,12 @@ import org.eclipse.cdt.internal.core.index.IWritableIndex;
  */
 public class YieldableIndexLock {
 	private final IWritableIndex index;
-	private final int readlockCount;
 	private final boolean flushIndex;
 	private long lastLockTime;
 	private long cumulativeLockTime;
 
-	public YieldableIndexLock(IWritableIndex index, int readlockCount, boolean flushIndex) {
+	public YieldableIndexLock(IWritableIndex index, boolean flushIndex) {
 		this.index = index;
-		this.readlockCount = readlockCount;
 		this.flushIndex = flushIndex;
 	}
 
@@ -36,7 +34,7 @@ public class YieldableIndexLock {
 	 * @throws InterruptedException
 	 */
 	public void acquire() throws InterruptedException {
-		index.acquireWriteLock(readlockCount);
+		index.acquireWriteLock();
 		lastLockTime = System.currentTimeMillis();
 	}
 
@@ -45,7 +43,7 @@ public class YieldableIndexLock {
 	 */
 	public void release() {
 		if (lastLockTime != 0) {
-			index.releaseWriteLock(readlockCount, flushIndex);
+			index.releaseWriteLock(flushIndex);
 			cumulativeLockTime += System.currentTimeMillis() - lastLockTime;
 			lastLockTime = 0;
 		}
@@ -58,7 +56,7 @@ public class YieldableIndexLock {
 	 */
 	public void yield() throws InterruptedException {
 		if (index.hasWaitingReaders()) {
-			index.releaseWriteLock(readlockCount, false);
+			index.releaseWriteLock(false);
 			cumulativeLockTime += System.currentTimeMillis() - lastLockTime;
 			lastLockTime = 0;
 			acquire();
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMASTAdapter.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMASTAdapter.java
index 5e11beb7dc2..8d630540efd 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMASTAdapter.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMASTAdapter.java
@@ -22,6 +22,7 @@ import org.eclipse.cdt.core.dom.ast.IASTImageLocation;
 import org.eclipse.cdt.core.dom.ast.IASTName;
 import org.eclipse.cdt.core.dom.ast.IASTNode;
 import org.eclipse.cdt.core.dom.ast.IASTNodeLocation;
+import org.eclipse.cdt.core.dom.ast.IASTPreprocessorIncludeStatement;
 import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit;
 import org.eclipse.cdt.core.dom.ast.IBinding;
 import org.eclipse.cdt.core.dom.ast.ICompositeType;
@@ -73,6 +74,10 @@ public class PDOMASTAdapter {
 				public int getNodeOffset() {
 					return loc.getNodeOffset();
 				}
+
+				public IASTPreprocessorIncludeStatement getContextInclusionStatement() {
+					return loc.getContextInclusionStatement();
+				}
 			};
 		}
 
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMFile.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMFile.java
index f8368489476..dac2a04cdc1 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMFile.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMFile.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2005, 2010 QNX Software Systems and others.
+ * Copyright (c) 2005, 2011 QNX Software Systems and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -16,7 +16,6 @@ package org.eclipse.cdt.internal.core.pdom.dom;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.ArrayList;
-import java.util.Collection;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
@@ -31,18 +30,19 @@ import org.eclipse.cdt.core.dom.ast.IBinding;
 import org.eclipse.cdt.core.dom.ast.IMacroBinding;
 import org.eclipse.cdt.core.dom.ast.IParameter;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPUsingDirective;
-import org.eclipse.cdt.core.index.IIndexFile;
 import org.eclipse.cdt.core.index.IIndexFileLocation;
 import org.eclipse.cdt.core.index.IIndexInclude;
 import org.eclipse.cdt.core.index.IIndexLocationConverter;
 import org.eclipse.cdt.core.index.IIndexMacro;
 import org.eclipse.cdt.core.index.IIndexName;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.internal.core.index.IIndexFragment;
 import org.eclipse.cdt.internal.core.index.IIndexFragmentFile;
 import org.eclipse.cdt.internal.core.index.IIndexFragmentName;
 import org.eclipse.cdt.internal.core.index.IWritableIndex.IncludeInformation;
 import org.eclipse.cdt.internal.core.index.IWritableIndexFragment;
 import org.eclipse.cdt.internal.core.index.IndexFileLocation;
+import org.eclipse.cdt.internal.core.parser.scanner.SignificantMacros;
 import org.eclipse.cdt.internal.core.pdom.PDOM;
 import org.eclipse.cdt.internal.core.pdom.YieldableIndexLock;
 import org.eclipse.cdt.internal.core.pdom.db.BTree;
@@ -56,28 +56,31 @@ import org.eclipse.core.runtime.Status;
 
 /**
  * Represents a file containing names.
- * 
+ *
  * @author Doug Schaefer
  */
 public class PDOMFile implements IIndexFragmentFile {
 	private final PDOMLinkage fLinkage;
 	private final long record;
-	private IIndexFileLocation location;  // No need to make volatile, all fields of IIndexFileLocation are final.
+	private IIndexFileLocation location;  // No need to make volatile, all fields of IndexFileLocation are final.
+	private ISignificantMacros sigMacros;  // No need to make volatile, all fields of SignificantMacros are either final or atomically updated.
 
 	private static final int FIRST_NAME = 0;
-	private static final int FIRST_INCLUDE = 4;
-	private static final int FIRST_INCLUDED_BY = 8;
-	private static final int FIRST_MACRO = 12;
-	private static final int LOCATION_REPRESENTATION = 16;
-	private static final int LINKAGE_ID= 20;
-	private static final int TIME_STAMP = 24;
-	private static final int CONTENT_HASH= 32;
-	private static final int SCANNER_CONFIG_HASH= 40;
-	private static final int ENCODING_HASH= 44;
-	private static final int LAST_USING_DIRECTIVE= 48;
-	private static final int FIRST_MACRO_REFERENCE= 52;
-
-	private static final int RECORD_SIZE= 56;
+	private static final int FIRST_INCLUDE = FIRST_NAME + Database.PTR_SIZE;
+	private static final int FIRST_INCLUDED_BY = FIRST_INCLUDE + Database.PTR_SIZE;
+	private static final int FIRST_MACRO = FIRST_INCLUDED_BY + Database.PTR_SIZE;
+	private static final int LOCATION_REPRESENTATION = FIRST_MACRO + Database.PTR_SIZE;
+	private static final int LINKAGE_ID= LOCATION_REPRESENTATION + Database.PTR_SIZE;  // size 3
+	private static final int FLAGS= LINKAGE_ID + 3;  // size 1
+	private static final int TIME_STAMP = FLAGS + 1; // long
+	private static final int CONTENT_HASH= TIME_STAMP + 8;  // long
+	private static final int ENCODING_HASH= CONTENT_HASH + 8;
+	private static final int LAST_USING_DIRECTIVE= ENCODING_HASH + 4;
+	private static final int FIRST_MACRO_REFERENCE= LAST_USING_DIRECTIVE + Database.PTR_SIZE;
+	private static final int SIGNIFICANT_MACROS= FIRST_MACRO_REFERENCE + Database.PTR_SIZE;
+	private static final int RECORD_SIZE= SIGNIFICANT_MACROS + Database.PTR_SIZE;   // 8*PTR_SIZE + 3+1+8+8+4 = 56
+
+	private static final int FLAG_PRAGMA_ONCE_SEMANTICS	= 0x01;
 
 	public static class Comparator implements IBTreeComparator {
 		private Database db;
@@ -91,10 +94,26 @@ public class PDOMFile implements IIndexFragmentFile {
 			IString name2 = db.getString(db.getRecPtr(record2 + LOCATION_REPRESENTATION));
 			int cmp= name1.compare(name2, true);
 			if (cmp == 0) {
-				cmp= db.getInt(record1 + LINKAGE_ID) - db.getInt(record2 + LINKAGE_ID);
+				cmp= db.get3ByteUnsignedInt(record1 + LINKAGE_ID) - db.get3ByteUnsignedInt(record2 + LINKAGE_ID);
+				if (cmp == 0) {
+					IString sm1= getString(record1 + SIGNIFICANT_MACROS);
+					IString sm2= getString(record2 + SIGNIFICANT_MACROS);
+					if (sm1 == null) {
+						cmp= sm2 == null ? 0 : -1;
+					} else if (sm2 == null) {
+						cmp= 1;
+					} else {
+						cmp= sm1.compare(sm2, true);
+					}
+				}
 			}
 			return cmp;
 		}
+		
+		private IString getString(long offset) throws CoreException {
+			long rec = db.getRecPtr(offset);
+			return rec != 0 ? db.getString(rec) : null;
+		}
 	}
 
 	public PDOMFile(PDOMLinkage linkage, long record) {
@@ -102,7 +121,7 @@ public class PDOMFile implements IIndexFragmentFile {
 		this.record = record;
 	}
 
-	public PDOMFile(PDOMLinkage linkage, IIndexFileLocation location, int linkageID) throws CoreException {
+	public PDOMFile(PDOMLinkage linkage, IIndexFileLocation location, int linkageID, ISignificantMacros macros) throws CoreException {
 		fLinkage = linkage;
 		this.location= location;
 		Database db = fLinkage.getDB();
@@ -112,7 +131,8 @@ public class PDOMFile implements IIndexFragmentFile {
 			throw new CoreException(CCorePlugin.createStatus(Messages.getString("PDOMFile.toInternalProblem") + location.getURI())); //$NON-NLS-1$
 		IString locationDBString = db.newString(locationString);
 		db.putRecPtr(record + LOCATION_REPRESENTATION, locationDBString.getRecord());
-		db.putInt(record + LINKAGE_ID, linkageID);
+		db.put3ByteUnsignedInt(record + LINKAGE_ID, linkageID);
+		db.putRecPtr(record + SIGNIFICANT_MACROS, db.newString(macros.encode()).getRecord());
 		setTimestamp(-1);
 	}
 
@@ -123,7 +143,7 @@ public class PDOMFile implements IIndexFragmentFile {
 	public PDOM getPDOM() {
 		return fLinkage.getPDOM();
 	}
-	
+
 	@Override
 	public boolean equals(Object obj) {
 		if (obj == this)
@@ -139,86 +159,45 @@ public class PDOMFile implements IIndexFragmentFile {
 	public final int hashCode() {
 		return System.identityHashCode(fLinkage.getPDOM()) + (int) (41 * record);
 	}
-	
+
 	/**
 	 * Transfers names, macros and includes from another file to this one and deletes the other file.
 	 * @param sourceFile the file to transfer the local bindings from.
 	 * @throws CoreException
 	 */
 	public void replaceContentsFrom(PDOMFile sourceFile) throws CoreException {
-		ICPPUsingDirective[] directives= getUsingDirectives();
-		for (ICPPUsingDirective ud : directives) {
-			if (ud instanceof IPDOMNode) {
-				((IPDOMNode) ud).delete(null);
-			}
-		}
-		setFirstUsingDirectiveRec(sourceFile.getLastUsingDirectiveRec());
+		// Delete current content
+		clear();
 
-		// Replace the includes
-		PDOMInclude include = getFirstInclude();
-		while (include != null) {
-			PDOMInclude nextInclude = include.getNextInIncludes();
-			IIndexFile includedBy = include.getIncludedBy();
-			if (this.equals(includedBy)) {
-				include.delete();
-			}
-			include = nextInclude;
-		}
-		include = sourceFile.getFirstInclude();
+		// Link in the using directives
+		setLastUsingDirective(sourceFile.getLastUsingDirectiveRec());
+
+		// Link in the includes, replace the owner.
+		PDOMInclude include = sourceFile.getFirstInclude();
 		setFirstInclude(include);
-		while (include != null) {
-			IIndexFile includedBy = include.getIncludedBy();
-			if (sourceFile.equals(includedBy)) {
-				include.setIncludedBy(this);
-				if (sourceFile.equals(include.getIncludes())) {
-					include.setIncludes(this);
-				}
-			}
-			include = include.getNextInIncludes();
+		for (; include != null; include= include.getNextInIncludes()) {
+			include.setIncludedBy(this);
 		}
 
-		// Replace all the macros in this file.
-		PDOMLinkage linkage= getLinkage();
-		PDOMMacro macro = getFirstMacro();
-		while (macro != null) {
-			PDOMMacro nextMacro = macro.getNextMacro();
-			macro.delete(linkage);
-			macro = nextMacro;
-		}
-		macro = sourceFile.getFirstMacro();
+		// In the unexpected case that there is an included by relation, append it.
+		transferIncluders(sourceFile);
+
+		// Link in the macros.
+		PDOMMacro macro = sourceFile.getFirstMacro();
 		setFirstMacro(macro);
 		for (; macro != null; macro = macro.getNextMacro()) {
 			macro.setFile(this);
 		}
 
-		// Replace all macro references
-		ArrayList<PDOMMacroReferenceName> mrefs= new ArrayList<PDOMMacroReferenceName>();
-		PDOMMacroReferenceName mref = getFirstMacroReference();
-		while (mref != null) {
-			mrefs.add(mref);
-			mref= mref.getNextInFile();
-		}
-		for (PDOMMacroReferenceName m : mrefs) {
-			m.delete();
-		}
-		mref = sourceFile.getFirstMacroReference();
+		// Link in macro references
+		PDOMMacroReferenceName mref = sourceFile.getFirstMacroReference();
 		setFirstMacroReference(mref);
 		for (; mref != null; mref = mref.getNextInFile()) {
 			mref.setFile(this);
 		}
 
 		// Replace all the names in this file
-		ArrayList<PDOMName> names= new ArrayList<PDOMName>();
-		PDOMName name = getFirstName();
-		for (; name != null; name= name.getNextInFile()) {
-			names.add(name);
-			linkage.onDeleteName(name);
-		}
-		for (Iterator<PDOMName> iterator = names.iterator(); iterator.hasNext();) {
-			name = iterator.next();
-			name.delete();
-		}
-		name = sourceFile.getFirstName();
+		PDOMName name = sourceFile.getFirstName();
 		setFirstName(name);
 		for (; name != null; name= name.getNextInFile()) {
 			name.setFile(this);
@@ -227,11 +206,58 @@ public class PDOMFile implements IIndexFragmentFile {
 		setTimestamp(sourceFile.getTimestamp());
 		setEncodingHashcode(sourceFile.getEncodingHashcode());
 		setContentsHash(sourceFile.getContentsHash());
-		setScannerConfigurationHashcode(sourceFile.getScannerConfigurationHashcode());
 
+		// Transfer the flags. 
+		Database db= fLinkage.getDB();
+		db.putByte(record + FLAGS, db.getByte(sourceFile.record + FLAGS));
+		
+		// Delete the source file
 		sourceFile.delete();
 	}
 
+	public void transferIncluders(IIndexFragmentFile sourceFile) throws CoreException {
+		PDOMFile source= (PDOMFile) sourceFile;
+		PDOMInclude include = source.getFirstIncludedBy();
+		if (include != null) {
+			// Detach the includes
+			source.setFirstIncludedBy(null);
+			// Adjust the includes
+			for (PDOMInclude i= include; i != null; i= i.getNextInIncludedBy()) {
+				i.setIncludes(this);
+			}
+			// Append the includes
+			PDOMInclude last= getFirstIncludedBy();
+			if (last == null) {
+				setFirstIncludedBy(include);
+			} else {
+				for (PDOMInclude i= last; i != null; i= i.getNextInIncludedBy()) {
+					last= i;
+				}
+				last.setNextInIncludedBy(include);
+				include.setPrevInIncludedBy(last);
+			}
+		}
+	}
+
+	public void transferContext(IIndexFragmentFile sourceFile) throws CoreException {
+		PDOMFile source= (PDOMFile) sourceFile;
+		PDOMInclude include = source.getFirstIncludedBy();
+		if (include != null) {
+			// Detach the include
+			final PDOMInclude next = include.getNextInIncludedBy();
+			include.setNextInIncludedBy(null);
+			source.setFirstIncludedBy(next);
+			if (next != null)
+				next.setPrevInIncludedBy(null);
+			
+			// Adjust the include
+			include.setIncludes(this);
+
+			// Insert the include
+			addIncludedBy(include, false);
+		}
+	}
+
 	/**
 	 * This method should not be called on PDOMFile objects that are referenced by the file index.
 	 * @param location a new location
@@ -239,9 +265,10 @@ public class PDOMFile implements IIndexFragmentFile {
 	 */
 	public void setLocation(IIndexFileLocation location) throws CoreException {
 		String locationString = fLinkage.getPDOM().getLocationConverter().toInternalFormat(location);
-		if (locationString == null)
+		if (locationString == null) {
 			throw new CoreException(CCorePlugin.createStatus(Messages.getString("PDOMFile.toInternalProblem") + //$NON-NLS-1$
 					location.getURI()));
+		}
 		setInternalLocation(locationString);
 	}
 
@@ -260,10 +287,10 @@ public class PDOMFile implements IIndexFragmentFile {
 		db.putRecPtr(record + LOCATION_REPRESENTATION, db.newString(internalLocation).getRecord());
 		location= null;
 	}
-	
+
 	public int getLinkageID() throws CoreException {
 		Database db = fLinkage.getDB();
-		return db.getInt(record + LINKAGE_ID);
+		return db.get3ByteUnsignedInt(record + LINKAGE_ID);
 	}
 
 	public long getTimestamp() throws CoreException {
@@ -287,13 +314,7 @@ public class PDOMFile implements IIndexFragmentFile {
 	}
 
 	public int getScannerConfigurationHashcode() throws CoreException {
-		Database db = fLinkage.getDB();
-		return db.getInt(record + SCANNER_CONFIG_HASH);
-	}
-
-	public void setScannerConfigurationHashcode(int hashcode) throws CoreException {
-		Database db= fLinkage.getDB();
-		db.putInt(record + SCANNER_CONFIG_HASH, hashcode);
+		return 0;
 	}
 
 	public int getEncodingHashcode() throws CoreException {
@@ -306,6 +327,21 @@ public class PDOMFile implements IIndexFragmentFile {
 		db.putInt(record + ENCODING_HASH, hashcode);
 	}
 
+	public boolean hasPragmaOnceSemantics() throws CoreException {
+		return (fLinkage.getDB().getByte(record + FLAGS) & FLAG_PRAGMA_ONCE_SEMANTICS) != 0;
+	}
+
+	public void setPragmaOnceSemantics(boolean value) throws CoreException {
+		Database db = fLinkage.getDB();
+		byte flags = db.getByte(record + FLAGS);
+		if (value) {
+			flags |= FLAG_PRAGMA_ONCE_SEMANTICS;
+		} else {
+			flags &= ~FLAG_PRAGMA_ONCE_SEMANTICS;
+		}
+		db.putByte(record + FLAGS, flags);
+	}
+
 	private PDOMName getFirstName() throws CoreException {
 		long namerec = fLinkage.getDB().getRecPtr(record + FIRST_NAME);
 		return namerec != 0 ? new PDOMName(fLinkage, namerec) : null;
@@ -340,7 +376,7 @@ public class PDOMFile implements IIndexFragmentFile {
 		long rec = fLinkage.getDB().getRecPtr(record + FIRST_INCLUDED_BY);
 		return rec != 0 ? new PDOMInclude(fLinkage, rec) : null;
 	}
-	
+
 	public IIndexInclude getParsedInContext() throws CoreException {
 		return getFirstIncludedBy();
 	}
@@ -459,22 +495,22 @@ public class PDOMFile implements IIndexFragmentFile {
 		return new PDOMMacroReferenceName(fLinkage, name, this, cont);
 	}
 
-	public void clear(Collection<IIndexFileLocation> contextsRemoved) throws CoreException {
+	public void clear() throws CoreException {
 		ICPPUsingDirective[] directives= getUsingDirectives();
 		for (ICPPUsingDirective ud : directives) {
 			if (ud instanceof IPDOMNode) {
 				((IPDOMNode) ud).delete(null);
 			}
 		}
-		setFirstUsingDirectiveRec(0);
+		setLastUsingDirective(0);
 
 		// Remove the includes
 		PDOMInclude include = getFirstInclude();
 		while (include != null) {
 			PDOMInclude nextInclude = include.getNextInIncludes();
-			if (contextsRemoved != null && include.getPrevInIncludedByRecord() == 0) {
-				contextsRemoved.add(include.getIncludesLocation());
-			}
+//			if (contextsRemoved != null && include.getPrevInIncludedByRecord() == 0) {
+//				contextsRemoved.add(include.getIncludesLocation());
+//			}
 			include.delete();
 			include = nextInclude;
 		}
@@ -515,7 +551,6 @@ public class PDOMFile implements IIndexFragmentFile {
 			m.delete();
 		}
 		setFirstMacroReference(null);
-
 		setTimestamp(-1);
 	}
 
@@ -529,6 +564,9 @@ public class PDOMFile implements IIndexFragmentFile {
 		long locRecord = db.getRecPtr(record + LOCATION_REPRESENTATION);
 		if (locRecord != 0)
 			db.getString(locRecord).delete();
+		locRecord = db.getRecPtr(record + SIGNIFICANT_MACROS);
+		if (locRecord != 0)
+			db.getString(locRecord).delete();
 
 		db.free(record);
 	}
@@ -539,7 +577,7 @@ public class PDOMFile implements IIndexFragmentFile {
 		PDOMInclude lastInclude= null;
 		for (final IncludeInformation info : includeInfos) {
 			final PDOMFile targetFile= (PDOMFile) info.fTargetFile;
-			
+
 			PDOMInclude pdomInclude = new PDOMInclude(fLinkage, info.fStatement, this, targetFile);
 			assert targetFile == null || targetFile.getIndexFragment() instanceof IWritableIndexFragment;
 			if (targetFile != null) {
@@ -560,7 +598,7 @@ public class PDOMFile implements IIndexFragmentFile {
 			if (isContext) {
 				setFirstIncludedBy(include);
 				include.setNextInIncludedBy(firstIncludedBy);
-				firstIncludedBy.setPrevInIncludedBy(include);				
+				firstIncludedBy.setPrevInIncludedBy(include);
 			} else {
 				PDOMInclude secondIncludedBy= firstIncludedBy.getNextInIncludedBy();
 				if (secondIncludedBy != null) {
@@ -606,13 +644,12 @@ public class PDOMFile implements IIndexFragmentFile {
 			if (nameOffset >= offset) {
 				if (nameOffset + name.getNodeLength() <= offset + length) {
 					result.add(name);
-				} else if (name.isReference()) { 
+				} else if (name.isReference()) {
 					// Names are ordered, but callers are inserted before
 					// their references.
 					break;
 				}
 			}
-
 		}
 		for (PDOMMacro macro= getFirstMacro(); macro != null; macro= macro.getNextMacro()) {
 			int nameOffset=  macro.getNodeOffset();
@@ -622,7 +659,7 @@ public class PDOMFile implements IIndexFragmentFile {
 					if (name != null) {
 						result.add(name);
 					}
-				} else { 
+				} else {
 					break;
 				}
 			}
@@ -632,7 +669,7 @@ public class PDOMFile implements IIndexFragmentFile {
 			if (nameOffset >= offset) {
 				if (nameOffset + name.getNodeLength() <= offset + length) {
 					result.add(name);
-				} else { 
+				} else {
 					break;
 				}
 			}
@@ -640,11 +677,53 @@ public class PDOMFile implements IIndexFragmentFile {
 		return result.toArray(new IIndexName[result.size()]);
 	}
 
+	public static IIndexFragmentFile[] findFiles(PDOMLinkage linkage, BTree btree, IIndexFileLocation location,
+			IIndexLocationConverter strategy) throws CoreException {
+		String internalRepresentation= strategy.toInternalFormat(location);
+		if (internalRepresentation != null) {
+			Finder finder = new Finder(linkage.getDB(), internalRepresentation, linkage.getLinkageID(), null);
+			btree.accept(finder);
+			long[] records= finder.getRecords();
+			IIndexFragmentFile[] result= new IIndexFragmentFile[records.length];
+			for (int i = 0; i < result.length; i++) {
+				result[i]= new PDOMFile(linkage, records[i]);
+			}
+			return result;
+		}
+		return IIndexFragmentFile.EMPTY_ARRAY;
+	}
+
+	/**
+	 * When a header file is stored in the index in multiple variants for different sets of macro
+	 * definitions this method will return an arbitrary one of these variants.
+	 *
+	 * @deprecated Use
+	 *     {@link #findFile(PDOMLinkage, BTree, IIndexFileLocation, IIndexLocationConverter, ISignificantMacros)}
+	 *     or {@link #findFiles(PDOMLinkage, BTree, IIndexFileLocation, IIndexLocationConverter)}
+	 */
+	@Deprecated
 	public static PDOMFile findFile(PDOMLinkage linkage, BTree btree, IIndexFileLocation location,
 			IIndexLocationConverter strategy) throws CoreException {
+		return findFile(linkage, btree, location, strategy, null);
+	}
+
+	/**
+	 * Finds the file in index.
+	 *
+	 * @param linkage The linkage of the file.
+	 * @param btree The file index.
+	 * @param location The location of the file.
+	 * @param strategy The index location converter.
+	 * @param macroDictionary The names and definitions of the macros used to disambiguate between
+	 *     variants of the file contents corresponding to different inclusion points.
+	 * @return The found file, or <code>null</code> if the matching file was not found.
+	 */
+	public static PDOMFile findFile(PDOMLinkage linkage, BTree btree, IIndexFileLocation location,
+			IIndexLocationConverter strategy, ISignificantMacros macroDictionary) throws CoreException {
 		String internalRepresentation= strategy.toInternalFormat(location);
 		if (internalRepresentation != null) {
-			Finder finder = new Finder(linkage.getDB(), internalRepresentation, linkage.getLinkageID());
+			Finder finder = new Finder(linkage.getDB(), internalRepresentation, linkage.getLinkageID(),
+					macroDictionary);
 			btree.accept(finder);
 			long record= finder.getRecord();
 			if (record != 0) {
@@ -658,7 +737,7 @@ public class PDOMFile implements IIndexFragmentFile {
 			IIndexLocationConverter strategy) throws CoreException {
 		String internalRepresentation= strategy.toInternalFormat(location);
 		if (internalRepresentation != null) {
-			Finder finder = new Finder(pdom.getDB(), internalRepresentation, -1);
+			Finder finder = new Finder(pdom.getDB(), internalRepresentation, -1, null);
 			btree.accept(finder);
 			long[] records= finder.getRecords();
 			PDOMFile[] result= new PDOMFile[records.length];
@@ -672,12 +751,11 @@ public class PDOMFile implements IIndexFragmentFile {
 
 	public static PDOMFile recreateFile(PDOM pdom, final long record) throws CoreException {
 		final Database db= pdom.getDB();
-		final int linkageID= db.getInt(record + PDOMFile.LINKAGE_ID);
+		final int linkageID= db.get3ByteUnsignedInt(record + LINKAGE_ID);
 		PDOMLinkage linkage= pdom.getLinkage(linkageID);
 		if (linkage == null)
 			throw new CoreException(createStatus("Invalid linkage ID in database")); //$NON-NLS-1$
-		PDOMFile file= new PDOMFile(linkage, record);
-		return file;
+		return new PDOMFile(linkage, record);
 	}
 
 	private static class Finder implements IBTreeVisitor {
@@ -687,14 +765,17 @@ public class PDOMFile implements IIndexFragmentFile {
 		private long record;
 		private long[] records;
 		private final int linkageID;
+		private char[] rawSignificantMacros;
 
 		/**
 		 * Searches for a file with the given linkage id.
 		 */
-		public Finder(Database db, String internalRepresentation, int linkageID) {
+		public Finder(Database db, String internalRepresentation, int linkageID, ISignificantMacros sigMacros) {
 			this.db = db;
 			this.rawKey = internalRepresentation;
 			this.linkageID= linkageID;
+			this.rawSignificantMacros = sigMacros == null ? null : sigMacros.encode();
+			assert linkageID >= 0 || rawSignificantMacros == null;
 		}
 
 		public long[] getRecords() {
@@ -706,32 +787,48 @@ public class PDOMFile implements IIndexFragmentFile {
 			}
 			return records;
 		}
-		
+
 		public int compare(long record) throws CoreException {
 			IString name = db.getString(db.getRecPtr(record + PDOMFile.LOCATION_REPRESENTATION));
 			int cmp= name.compare(rawKey, true);
 			if (cmp == 0 && linkageID >= 0) {
-				cmp= db.getInt(record + PDOMFile.LINKAGE_ID) - linkageID;
+				cmp= db.get3ByteUnsignedInt(record + PDOMFile.LINKAGE_ID) - linkageID;
+				if (cmp == 0 && rawSignificantMacros != null) {
+					IString significantMacrosStr = getString(record + SIGNIFICANT_MACROS);
+					if (significantMacrosStr != null) {
+						cmp = significantMacrosStr.compare(rawSignificantMacros, true);
+					} else {
+						cmp = rawSignificantMacros.length > 0 ? -1 : 0;
+					}
+				}
 			}
 			return cmp;
 		}
-		
+
+		private IString getString(long offset) throws CoreException {
+			long rec = db.getRecPtr(offset);
+			return rec != 0 ? db.getString(rec) : null;
+		}
+
 		public boolean visit(long record) throws CoreException {
-			if (linkageID >= 0) {
+			if (rawSignificantMacros != null) {
 				this.record = record;
-				return false;
+				return false; 
+				// Stop searching.
 			}
+			
 			if (this.record == 0) {
 				this.record= record;
 			} else if (this.records == null) {
-				this.records= new long[] {this.record, record};
+				this.records= new long[] { this.record, record };
 			} else {
 				long[] cpy= new long[this.records.length + 1];
 				System.arraycopy(this.records, 0, cpy, 0, this.records.length);
 				cpy[cpy.length - 1]= record;
 				this.records= cpy;
 			}
-			return linkageID < 0;
+			// Continue search.
+			return true;
 		}
 
 		public long getRecord() {
@@ -757,7 +854,17 @@ public class PDOMFile implements IIndexFragmentFile {
 		}
 		return location;
 	}
+
 	
+	public ISignificantMacros getSignificantMacros() throws CoreException {
+		if (sigMacros == null) {
+			Database db= fLinkage.getDB();
+			final IString encoded = db.getString(db.getRecPtr(record + SIGNIFICANT_MACROS));
+			sigMacros= encoded == null ? ISignificantMacros.NONE : new SignificantMacros(encoded.getChars());
+		}
+		return sigMacros;
+	}
+
 	public boolean hasContent() throws CoreException {
 		return getTimestamp() != -1;
 	}
@@ -779,7 +886,7 @@ public class PDOMFile implements IIndexFragmentFile {
 		return fLinkage.getDB().getRecPtr(record + LAST_USING_DIRECTIVE);
 	}
 
-	public void setFirstUsingDirectiveRec(long rec) throws CoreException {
+	public void setLastUsingDirective(long rec) throws CoreException {
 		fLinkage.getDB().putRecPtr(record + LAST_USING_DIRECTIVE, rec);
 	}
 
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMLinkage.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMLinkage.java
index 35cc42ef67b..78d13b8b15b 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMLinkage.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMLinkage.java
@@ -256,9 +256,9 @@ public abstract class PDOMLinkage extends PDOMNamedNode implements IIndexLinkage
 			}
 
 			if (checkIfInSourceOnly) {
-				String path= ASTInternal.getDeclaredInSourceFileOnly(binding, requireDefinition, glob);
-				if (path != null) {
-					return wpdom.getFileForASTPath(getLinkageID(), path);
+				IASTNode node= ASTInternal.getDeclaredInSourceFileOnly(binding, requireDefinition, glob);
+				if (node != null) {
+					return wpdom.getFileForASTNode(getLinkageID(), node);
 				}
 			}
 		}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMMacro.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMMacro.java
index 7ea5c88564d..8f8b0a6f10d 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMMacro.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMMacro.java
@@ -20,6 +20,7 @@ import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.dom.IPDOMVisitor;
 import org.eclipse.cdt.core.dom.ast.IASTFileLocation;
 import org.eclipse.cdt.core.dom.ast.IASTName;
+import org.eclipse.cdt.core.dom.ast.IASTPreprocessorIncludeStatement;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorMacroDefinition;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorUndefStatement;
 import org.eclipse.cdt.core.dom.ast.IMacroBinding;
@@ -278,10 +279,6 @@ public class PDOMMacro implements IIndexMacro, IPDOMBinding, IASTFileLocation {
 		fLinkage.getDB().putRecPtr(fRecord + FILE, file != null ? file.getRecord() : 0);
 	}
 
-	public int getEndingLineNumber() {
-		return 0;
-	}
-
 	public String getFileName() {
 		try {
 			IIndexFile file = getFile();
@@ -303,6 +300,14 @@ public class PDOMMacro implements IIndexMacro, IPDOMBinding, IASTFileLocation {
 		return 0;
 	}
 
+	public int getEndingLineNumber() {
+		return 0;
+	}
+
+	public IASTPreprocessorIncludeStatement getContextInclusionStatement() {
+		return null;
+	}
+
 	public IASTFileLocation asFileLocation() {
 		return this;
 	}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMMacroReferenceName.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMMacroReferenceName.java
index dc2807e21d4..ff242e63d2e 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMMacroReferenceName.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMMacroReferenceName.java
@@ -15,6 +15,7 @@ package org.eclipse.cdt.internal.core.pdom.dom;
 import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.dom.ast.IASTFileLocation;
 import org.eclipse.cdt.core.dom.ast.IASTName;
+import org.eclipse.cdt.core.dom.ast.IASTPreprocessorIncludeStatement;
 import org.eclipse.cdt.core.index.IIndexFile;
 import org.eclipse.cdt.core.index.IIndexName;
 import org.eclipse.cdt.core.index.IndexLocationFactory;
@@ -216,6 +217,10 @@ public final class PDOMMacroReferenceName implements IIndexFragmentName, IASTFil
 		return 0;
 	}
 
+	public IASTPreprocessorIncludeStatement getContextInclusionStatement() {
+		return null;
+	}
+
 	public IASTFileLocation asFileLocation() {
 		return this;
 	}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMName.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMName.java
index f8a5bb59273..cad23af7f64 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMName.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/PDOMName.java
@@ -6,9 +6,9 @@
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
- *    Doug Schaefer (QNX) - Initial API and implementation
- *    Markus Schorn (Wind River Systems)
- *    Sergey Prigogin (Google)
+ *     Doug Schaefer (QNX) - Initial API and implementation
+ *     Markus Schorn (Wind River Systems)
+ *     Sergey Prigogin (Google)
  *******************************************************************************/
 package org.eclipse.cdt.internal.core.pdom.dom;
 
@@ -17,6 +17,7 @@ import java.util.ArrayList;
 import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.dom.ast.IASTFileLocation;
 import org.eclipse.cdt.core.dom.ast.IASTName;
+import org.eclipse.cdt.core.dom.ast.IASTPreprocessorIncludeStatement;
 import org.eclipse.cdt.core.index.IIndexFile;
 import org.eclipse.cdt.core.index.IIndexName;
 import org.eclipse.cdt.core.index.IndexLocationFactory;
@@ -323,6 +324,10 @@ public final class PDOMName implements IIndexFragmentName, IASTFileLocation {
 		return 0;
 	}
 
+	public IASTPreprocessorIncludeStatement getContextInclusionStatement() {
+		return null;
+	}
+
 	public IASTFileLocation asFileLocation() {
 		return this;
 	}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/cpp/PDOMCPPLinkage.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/cpp/PDOMCPPLinkage.java
index eb3c04ceb0e..e11ac1d195b 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/cpp/PDOMCPPLinkage.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/dom/cpp/PDOMCPPLinkage.java
@@ -890,7 +890,7 @@ class PDOMCPPLinkage extends PDOMLinkage implements IIndexCPPBindingConstants {
 				long rec= file.getLastUsingDirectiveRec();
 				PDOMCPPUsingDirective ud= new PDOMCPPUsingDirective(this, rec, containerNS,
 						pdomName.getBinding(), pdomName.getFileLocation().getNodeOffset());
-				file.setFirstUsingDirectiveRec(ud.getRecord());
+				file.setLastUsingDirective(ud.getRecord());
 			}
 		} else if (parentNode instanceof ICPPASTElaboratedTypeSpecifier) {
 			ICPPASTElaboratedTypeSpecifier elaboratedSpecifier = (ICPPASTElaboratedTypeSpecifier)parentNode;
@@ -983,23 +983,23 @@ class PDOMCPPLinkage extends PDOMLinkage implements IIndexCPPBindingConstants {
 			final WritablePDOM wpdom= (WritablePDOM) pdom;
 			PDOMFile file= null;
 			if (binding instanceof ICPPUsingDeclaration) {
-				String path= ASTInternal.getDeclaredInOneFileOnly(binding);
-				if (path != null) {
-					file= wpdom.getFileForASTPath(getLinkageID(), path);
+				IASTNode node= ASTInternal.getDeclaredInOneFileOnly(binding);
+				if (node != null) {
+					file= wpdom.getFileForASTNode(getLinkageID(), node);
 				}
 			} else if (binding instanceof ICPPNamespaceAlias) {
-				String path= ASTInternal.getDeclaredInSourceFileOnly(binding, false, glob);
-				if (path != null) {
-					file= wpdom.getFileForASTPath(getLinkageID(), path);
+				IASTNode node= ASTInternal.getDeclaredInSourceFileOnly(binding, false, glob);
+				if (node != null) {
+					file= wpdom.getFileForASTNode(getLinkageID(), node);
 				}
 			}
 			if (file == null && !(binding instanceof IIndexBinding)) {
 				IBinding owner= binding.getOwner();
 				if (owner instanceof ICPPNamespace) {
 					if (owner.getNameCharArray().length == 0) {
-						String path= ASTInternal.getDeclaredInSourceFileOnly(owner, false, glob);
-						if (path != null) {
-							file= wpdom.getFileForASTPath(getLinkageID(), path);
+						IASTNode node= ASTInternal.getDeclaredInSourceFileOnly(owner, false, glob);
+						if (node != null) {
+							file= wpdom.getFileForASTNode(getLinkageID(), node);
 						}
 					}
 				}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/AbstractPDOMIndexer.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/AbstractPDOMIndexer.java
index b17b9f9f522..34140806933 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/AbstractPDOMIndexer.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/AbstractPDOMIndexer.java
@@ -21,6 +21,9 @@ import org.eclipse.cdt.core.model.ICProject;
  * Abstract base class for all indexers.
  */
 public abstract class AbstractPDOMIndexer implements IPDOMIndexer {
+	// For testing purposes
+	public static boolean noFilesUpFront= false;
+	
 	protected ICProject project;
 	protected Properties fProperties= new Properties();
 		
@@ -82,11 +85,13 @@ public abstract class AbstractPDOMIndexer implements IPDOMIndexer {
 	}
 
 	public String[] getFilesToParseUpFront() {
-		String prefSetting= getProperty(IndexerPreferences.KEY_FILES_TO_PARSE_UP_FRONT);
-		if (prefSetting != null) {
-			prefSetting= prefSetting.trim();
-			if (prefSetting.length() > 0) {
-				return prefSetting.split(","); //$NON-NLS-1$
+		if (!noFilesUpFront) {
+			String prefSetting= getProperty(IndexerPreferences.KEY_FILES_TO_PARSE_UP_FRONT);
+			if (prefSetting != null) {
+				prefSetting= prefSetting.trim();
+				if (prefSetting.length() > 0) {
+					return prefSetting.split(","); //$NON-NLS-1$
+				}
 			}
 		}
 		return new String[0];
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/PDOMIndexerTask.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/PDOMIndexerTask.java
index 9fba3a7cd2c..cd99d472626 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/PDOMIndexerTask.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/PDOMIndexerTask.java
@@ -15,37 +15,25 @@ import java.util.Arrays;
 import java.util.Calendar;
 import java.util.Comparator;
 import java.util.HashSet;
-import java.util.Map;
 
 import org.eclipse.cdt.core.CCorePlugin;
-import org.eclipse.cdt.core.dom.ILinkage;
 import org.eclipse.cdt.core.dom.IPDOMIndexer;
 import org.eclipse.cdt.core.dom.IPDOMIndexerTask;
 import org.eclipse.cdt.core.index.IIndexManager;
-import org.eclipse.cdt.core.model.AbstractLanguage;
 import org.eclipse.cdt.core.model.ICProject;
-import org.eclipse.cdt.core.model.ILanguage;
 import org.eclipse.cdt.core.model.ITranslationUnit;
-import org.eclipse.cdt.core.model.LanguageManager;
-import org.eclipse.cdt.core.parser.IScannerInfo;
-import org.eclipse.cdt.core.parser.IScannerInfoProvider;
-import org.eclipse.cdt.core.parser.ScannerInfo;
 import org.eclipse.cdt.internal.core.index.IWritableIndex;
 import org.eclipse.cdt.internal.core.index.IWritableIndexManager;
 import org.eclipse.cdt.internal.core.pdom.AbstractIndexerTask;
 import org.eclipse.cdt.internal.core.pdom.ITodoTaskUpdater;
 import org.eclipse.cdt.internal.core.pdom.IndexerProgress;
 import org.eclipse.cdt.internal.core.pdom.db.ChunkCache;
-import org.eclipse.core.resources.IFile;
-import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.IResource;
 import org.eclipse.core.runtime.CoreException;
-import org.eclipse.core.runtime.IPath;
 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Platform;
 import org.eclipse.core.runtime.Status;
-import org.eclipse.core.runtime.content.IContentType;
 import org.eclipse.osgi.util.NLS;
 
 import com.ibm.icu.text.NumberFormat;
@@ -177,59 +165,6 @@ public abstract class PDOMIndexerTask extends AbstractIndexerTask implements IPD
 		return defaultValue;
 	}
 
-	@Override
-	protected String getASTPathForParsingUpFront() {
-		final IProject project = getProject().getProject();
-		final IPath prjLocation= project.getLocation();
-		if (prjLocation == null) {
-			return null;
-		}
-		return prjLocation.append(super.getASTPathForParsingUpFront()).toString();
-	}
-
-	@Override
-	protected AbstractLanguage[] getLanguages(String filename) {
-		IProject project = getProject().getProject();
-		IContentType ct= CCorePlugin.getContentType(project, filename);
-		if (ct != null) {
-			ILanguage l = LanguageManager.getInstance().getLanguage(ct, project);
-			if (l instanceof AbstractLanguage) {
-				if (filename.indexOf('.') >= 0 && ct.getId().equals(CCorePlugin.CONTENT_TYPE_CXXHEADER) &&
-						l.getLinkageID() == ILinkage.CPP_LINKAGE_ID) {
-					ILanguage l2= LanguageManager.getInstance().getLanguageForContentTypeID(CCorePlugin.CONTENT_TYPE_CHEADER);
-					if (l2 instanceof AbstractLanguage) {
-						return new AbstractLanguage[] {(AbstractLanguage) l, (AbstractLanguage) l2};
-					}
-				}
-				return new AbstractLanguage[] {(AbstractLanguage) l};
-			}
-		}
-		return new AbstractLanguage[0];
-	}
-
-	@Override
-	protected IScannerInfo createDefaultScannerConfig(int linkageID) {
-		IProject project= getProject().getProject();
-		IScannerInfoProvider provider= CCorePlugin.getDefault().getScannerInfoProvider(project);
-		IScannerInfo scanInfo;
-		if (provider != null) {
-			String filename= linkageID == ILinkage.C_LINKAGE_ID ? "__cdt__.c" : "__cdt__.cpp";  //$NON-NLS-1$//$NON-NLS-2$
-			IFile file= project.getFile(filename);
-			scanInfo= provider.getScannerInformation(file);
-			if (scanInfo == null || scanInfo.getDefinedSymbols().isEmpty()) {
-				scanInfo= provider.getScannerInformation(project);
-			}
-			if (linkageID == ILinkage.C_LINKAGE_ID) {
-				final Map<String, String> definedSymbols = scanInfo.getDefinedSymbols();
-				definedSymbols.remove("__cplusplus__"); //$NON-NLS-1$
-				definedSymbols.remove("__cplusplus"); //$NON-NLS-1$
-			}
-		} else {
-			scanInfo= new ScannerInfo();
-		}
-		return scanInfo;
-	}
-
 	private ICProject getProject() {
 		return getIndexer().getProject();
 	}
@@ -406,4 +341,4 @@ public abstract class PDOMIndexerTask extends AbstractIndexerTask implements IPD
 		}
 		return super.acceptUrgentTask(urgentTask);
 	}
-}
\ No newline at end of file
+}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/PDOMRebuildTask.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/PDOMRebuildTask.java
index 9c93a98cae3..37f82a39365 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/PDOMRebuildTask.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/PDOMRebuildTask.java
@@ -88,7 +88,7 @@ public class PDOMRebuildTask implements IPDOMIndexerTask {
 	
 	private void clearIndex(ICProject project, IWritableIndex index) throws CoreException, InterruptedException {
 		// First clear the pdom
-		index.acquireWriteLock(0);
+		index.acquireWriteLock();
 		try {
 			index.clear();
 			IWritableIndexFragment wf= index.getWritableFragment();
@@ -96,7 +96,7 @@ public class PDOMRebuildTask implements IPDOMIndexerTask {
 				PDOMManager.writeProjectPDOMProperties((WritablePDOM) wf, project.getProject());
 			}
 		} finally {
-			index.releaseWriteLock(0);
+			index.releaseWriteLock();
 		}
 	}
 
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/ProjectIndexerInputAdapter.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/ProjectIndexerInputAdapter.java
index 2c712127471..85a503c9141 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/ProjectIndexerInputAdapter.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/ProjectIndexerInputAdapter.java
@@ -146,7 +146,7 @@ public class ProjectIndexerInputAdapter extends IndexerInputAdapter {
 	public String getASTPath(IIndexFileLocation ifl) {
 		IPath path= IndexLocationFactory.getAbsolutePath(ifl);
 		if (path != null) {
-			return path.toString();
+			return path.toOSString();
 		}
 		return ifl.getURI().getPath();
 	}
diff --git a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/parser/ParserLogService.java b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/parser/ParserLogService.java
index 5f6eb04e6b0..c08ca43d547 100644
--- a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/parser/ParserLogService.java
+++ b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/parser/ParserLogService.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2002, 2008 IBM Corporation and others.
+ * Copyright (c) 2002, 2011 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -19,6 +19,7 @@ import org.eclipse.cdt.internal.core.model.DebugLogConstants;
 import org.eclipse.cdt.internal.core.model.Util;
 import org.eclipse.cdt.internal.core.util.ICancelable;
 import org.eclipse.cdt.internal.core.util.ICanceler;
+import org.eclipse.core.runtime.Platform;
 
 /**
  * @author jcamelon
@@ -53,6 +54,16 @@ public class ParserLogService extends AbstractParserLogService implements ICance
 		Util.debugLog( message, topic );
 	}
 
+	@Override
+	public boolean isTracing(String option) {
+		return "true".equals(Platform.getDebugOption(option)); //$NON-NLS-1$
+	}
+	
+	@Override
+	public void traceLog(String option, String message) {
+		if (isTracing(option)) 
+			System.out.println(message);
+	}
 
 	@Override
 	public void errorLog(String message) {
diff --git a/core/org.eclipse.cdt.ui.tests/ui/org/eclipse/cdt/ui/tests/includebrowser/BasicIncludeBrowserTest.java b/core/org.eclipse.cdt.ui.tests/ui/org/eclipse/cdt/ui/tests/includebrowser/BasicIncludeBrowserTest.java
index 6c82b07a5bf..f5174157a6a 100644
--- a/core/org.eclipse.cdt.ui.tests/ui/org/eclipse/cdt/ui/tests/includebrowser/BasicIncludeBrowserTest.java
+++ b/core/org.eclipse.cdt.ui.tests/ui/org/eclipse/cdt/ui/tests/includebrowser/BasicIncludeBrowserTest.java
@@ -16,6 +16,7 @@ import junit.framework.Test;
 import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.swt.widgets.Tree;
+import org.eclipse.swt.widgets.TreeItem;
 
 import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.dom.IPDOMManager;
@@ -37,6 +38,7 @@ public class BasicIncludeBrowserTest extends IncludeBrowserBaseTest {
 	// // source
 	// #include "user.h"
 	// #include <system.h>
+	// #include "user.h"
 	
 	public void testSimpleInclusion() throws Exception {
 		TestScannerProvider.sIncludes= new String[] { getProject().getProject().getLocation().toOSString() };
@@ -50,9 +52,10 @@ public class BasicIncludeBrowserTest extends IncludeBrowserBaseTest {
 
 		openIncludeBrowser(source);
 		Tree tree = getIBTree();
-		checkTreeNode(tree, 0, "source.cpp");
+		TreeItem node = checkTreeNode(tree, 0, "source.cpp");
 		checkTreeNode(tree, 0, 0, "user.h");
 		checkTreeNode(tree, 0, 1, "system.h");
+		assertEquals(2, node.getItemCount());
 		
 		// The tree has to be reversed
 		openIncludeBrowser(user, true);
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/actions/CreateParserLogAction.java b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/actions/CreateParserLogAction.java
index bd047e26758..245816efe30 100644
--- a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/actions/CreateParserLogAction.java
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/actions/CreateParserLogAction.java
@@ -15,11 +15,13 @@ import java.io.IOException;
 import java.io.PrintStream;
 import java.util.ArrayList;
 import java.util.Comparator;
+import java.util.Date;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
 import java.util.TreeMap;
@@ -42,6 +44,7 @@ import org.eclipse.ui.IWorkbenchPart;
 import org.eclipse.ui.IWorkbenchPartSite;
 
 import org.eclipse.cdt.core.CCorePlugin;
+import org.eclipse.cdt.core.dom.ILinkage;
 import org.eclipse.cdt.core.dom.ast.ASTVisitor;
 import org.eclipse.cdt.core.dom.ast.IASTName;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorIncludeStatement;
@@ -55,12 +58,14 @@ import org.eclipse.cdt.core.index.IIndex;
 import org.eclipse.cdt.core.index.IIndexFile;
 import org.eclipse.cdt.core.index.IIndexFileLocation;
 import org.eclipse.cdt.core.index.IIndexInclude;
+import org.eclipse.cdt.core.index.IndexLocationFactory;
 import org.eclipse.cdt.core.model.CModelException;
+import org.eclipse.cdt.core.model.CoreModelUtil;
 import org.eclipse.cdt.core.model.ICProject;
 import org.eclipse.cdt.core.model.ILanguage;
 import org.eclipse.cdt.core.model.ITranslationUnit;
 import org.eclipse.cdt.core.parser.ExtendedScannerInfo;
-import org.eclipse.cdt.core.parser.IScannerInfoProvider;
+import org.eclipse.cdt.core.parser.ISignificantMacros;
 import org.eclipse.cdt.core.settings.model.ICConfigurationDescription;
 import org.eclipse.cdt.core.settings.model.ICProjectDescription;
 import org.eclipse.cdt.core.settings.model.ICProjectDescriptionManager;
@@ -76,6 +81,7 @@ import org.eclipse.cdt.internal.ui.editor.ASTProvider;
 
 @SuppressWarnings("nls")
 public class CreateParserLogAction implements IObjectActionDelegate {
+	private static final String INDENT = "   ";
 
 	private static final class MyVisitor extends ASTVisitor {
 		List<IASTProblem> fProblems= new ArrayList<IASTProblem>();
@@ -118,6 +124,8 @@ public class CreateParserLogAction implements IObjectActionDelegate {
 
 	private ISelection fSelection;
 	private IWorkbenchPartSite fSite;
+
+	private boolean fWroteUnresolvedTitle;
 	
 	public void setActivePart(IAction action, IWorkbenchPart targetPart) {
 		fSite= targetPart.getSite();
@@ -209,81 +217,90 @@ public class CreateParserLogAction implements IObjectActionDelegate {
 		IStatus status = Status.OK_STATUS;
 		final ICProject cproject = tu.getCProject();
 		final String projectName= cproject == null ? null : cproject.getElementName();
-		String scannerInfoProvider= "null";
-		if (cproject != null) {
-			IScannerInfoProvider provider = CCorePlugin.getDefault().getScannerInfoProvider(cproject.getProject());
-			if (provider != null) {
-				scannerInfoProvider= provider.getClass().getName();
-			}
-		}	
-		
-		ITranslationUnit ctx= tu;
+		final IIndex index = ast.getIndex();
+
+		ITranslationUnit configureWith = tu;
+		int ctxLinkage= 0;
+		ISignificantMacros ctxSigMacros= null;
 		if (tu instanceof TranslationUnit) {
 			TranslationUnit itu= (TranslationUnit) tu;
-			ctx= itu.getSourceContextTU(ast.getIndex(), ITranslationUnit.AST_CONFIGURE_USING_SOURCE_CONTEXT);
+			IIndexFile[] ctxToHeader = itu.getContextToHeader(index, ITranslationUnit.AST_CONFIGURE_USING_SOURCE_CONTEXT);
+			if (ctxToHeader != null) {
+				try {
+					final IIndexFile ctxFile = ctxToHeader[0];
+					ctxLinkage= ctxToHeader[0].getLinkageID();
+					ctxSigMacros= ctxFile.getSignificantMacros();
+					configureWith = CoreModelUtil.findTranslationUnitForLocation(ctxFile.getLocation(), cproject);
+				} catch (CoreException e) {
+				}
+				if (configureWith == null) {
+					configureWith= tu;
+					ctxToHeader= null;
+				}
+			}
 		}
-		final ExtendedScannerInfo scfg= new ExtendedScannerInfo(ctx.getScannerInfo(true));
-		final String indent= "   "; 
+
+		final ExtendedScannerInfo scfg= new ExtendedScannerInfo(configureWith.getScannerInfo(true));
 		final MyVisitor visitor= new MyVisitor();
 		ast.accept(visitor);
 		
 		out.println("Project:               " + projectName); 
+		out.println("File:                  " + tu.getLocationURI()); 
+		out.println("Language:              " + lang.getName()); 
 		out.println("Index Version:         " + PDOM.versionString(PDOM.getDefaultVersion())); 
-		out.println("Scanner Info Provider: " + scannerInfoProvider);
 		out.println("Build Configuration:   " + getBuildConfig(cproject));
-		out.println("File:      " + tu.getLocationURI()); 
-		out.println("Context:   " + ctx.getLocationURI()); 
-		out.println("Language:  " + lang.getName()); 
-		out.println();
-		out.println("Include Search Path (option -I):");  
-		output(out, indent, scfg.getIncludePaths());
-		out.println();
-		out.println("Local Include Search Path (option -iquote):"); 
-		output(out, indent, scfg.getLocalIncludePath());
-		out.println();
-		out.println("Preincluded files (option -include):"); 
-		output(out, indent, scfg.getIncludeFiles());
-		out.println();
-		out.println("Preincluded macro files (option -imacros):"); 
-		output(out, indent, scfg.getMacroFiles());
-		out.println();
-		out.println("Macro definitions (option -D):"); 
-		HashSet<String> reported= new HashSet<String>();
-		output(out, indent, scfg.getDefinedSymbols(), reported);
-		out.println();
-		out.println("Macro definitions (from configuration + headers in index):"); 
-		output(out, indent, ast.getBuiltinMacroDefinitions(), reported);
-		out.println();
-		out.println("Macro definitions (from files actually parsed):"); 
-		output(out, indent, ast.getMacroDefinitions(), reported);
-
-		out.println();
-		out.println("Unresolved includes (from headers in index):"); 
+		if (configureWith == tu) {
+			out.println("Context:               none");
+		} else {
+			out.println("Context:               " + configureWith.getLocationURI());
+			out.println(INDENT + getLinkageName(ctxLinkage) + ", " + ctxSigMacros);
+		}
+		
 		try {
-			outputUnresolvedIncludes(cproject, ast.getIndex(), out, indent, ast.getIncludeDirectives(), ast.getLinkage().getLinkageID());
+			IIndexFile[] versions= index.getFiles(IndexLocationFactory.getIFL(tu));
+			out.println("Versions in Index:     " + versions.length);
+			for (IIndexFile f : versions) {
+				out.println(INDENT + getLinkageName(f.getLinkageID()) + ": " + f.getSignificantMacros());
+			}
 		} catch (CoreException e) {
 			status= e.getStatus();
 		}
-		
 		out.println();
-		out.println("Scanner problems:"); 
-		output(out, indent, ast.getPreprocessorProblems());
 
-		out.println();
-		out.println("Parser problems:"); 
-		output(out, indent, visitor.fProblems.toArray(new IASTProblem[visitor.fProblems.size()]));
+		output(out, "Include Search Path (option -I):", scfg.getIncludePaths());
+		output(out, "Local Include Search Path (option -iquote):", scfg.getLocalIncludePath());
+		output(out, "Preincluded files (option -include):", scfg.getIncludeFiles());
+		output(out, "Preincluded macro files (option -imacros):", scfg.getMacroFiles());
 		
-		out.println();
-		out.println("Unresolved names:"); 
-		output(out, indent, visitor.fProblemBindings);
-
-		out.println();
-		out.println("Exceptions in name resolution:"); 
-		output(out, visitor.fExceptions);
+		HashSet<String> reported= new HashSet<String>();
+		output(out, "Macro definitions (option -D):", scfg.getDefinedSymbols(), reported);
+		output(out, "Macro definitions (from language + headers in index):", ast.getBuiltinMacroDefinitions(), reported);
+		output(out, "Macro definitions (from files actually parsed):", ast.getMacroDefinitions(), reported);
 
+		try {
+			outputUnresolvedIncludes(cproject, ast.getIndex(), out, ast.getIncludeDirectives(), ast.getLinkage().getLinkageID());
+		} catch (CoreException e) {
+			status= e.getStatus();
+		}
+		output(out, "Scanner problems:", ast.getPreprocessorProblems());
+		output(out, "Parser problems:", visitor.fProblems.toArray(new IASTProblem[0]));
+		output(out, "Unresolved names:", visitor.fProblemBindings.toArray(new IProblemBinding[0]));
+		output(out, "Exceptions in name resolution:", visitor.fExceptions);
+		out.println("Written on " + new Date().toString());
 		return status;
 	}
 
+	private String getLinkageName(int linkageID) {
+		switch(linkageID) {
+		case ILinkage.NO_LINKAGE_ID: return ILinkage.NO_LINKAGE_NAME;
+		case ILinkage.C_LINKAGE_ID: return ILinkage.C_LINKAGE_NAME;
+		case ILinkage.CPP_LINKAGE_ID: return ILinkage.CPP_LINKAGE_NAME;
+		case ILinkage.FORTRAN_LINKAGE_ID: return ILinkage.FORTRAN_LINKAGE_NAME;
+		case ILinkage.OBJC_LINKAGE_ID: return ILinkage.OBJC_LINKAGE_NAME;
+		}
+		return String.valueOf(linkageID);
+	}
+
 	private String getBuildConfig(ICProject cproject) {
     	ICProjectDescriptionManager prjDescMgr= CCorePlugin.getDefault().getProjectDescriptionManager();
     	ICProjectDescription prefs= prjDescMgr.getProjectDescription(cproject.getProject(), false);
@@ -295,35 +312,37 @@ public class CreateParserLogAction implements IObjectActionDelegate {
     	return "unknown";
 	}
 
-	private void outputUnresolvedIncludes(ICProject prj, IIndex index, PrintStream out, String indent, 
+	private void outputUnresolvedIncludes(ICProject prj, IIndex index, PrintStream out, 
 			IASTPreprocessorIncludeStatement[] includeDirectives, int linkageID) throws CoreException {
+		fWroteUnresolvedTitle= false;
 		ASTFilePathResolver resolver= new ProjectIndexerInputAdapter(prj);
-		HashSet<IIndexFileLocation> handled= new HashSet<IIndexFileLocation>();
+		HashSet<IIndexFile> handled= new HashSet<IIndexFile>();
 		for (IASTPreprocessorIncludeStatement include : includeDirectives) {
-			if (include.isActive() && include.isResolved()) {
-				outputUnresolvedIncludes(index, out, indent, resolver.resolveASTPath(include.getPath()), linkageID, handled);
+			if (include.isResolved()) {
+				IIndexFileLocation ifl = resolver.resolveASTPath(include.getPath());
+				IIndexFile ifile= index.getFile(linkageID, ifl, include.getSignificantMacros());
+				outputUnresolvedIncludes(index, out, ifl, ifile, handled);
 			}
 		}
+		if (fWroteUnresolvedTitle)
+			out.println();
 	}
 
-	private void outputUnresolvedIncludes(IIndex index, PrintStream out, String indent, 
-			IIndexFileLocation ifl, int linkageID, HashSet<IIndexFileLocation> handled) throws CoreException {
-		if (!handled.add(ifl)) {
-			return;
-		}
-		IIndexFile ifile= index.getFile(linkageID, ifl);
+	private void outputUnresolvedIncludes(IIndex index, PrintStream out,  
+			IIndexFileLocation ifl, IIndexFile ifile, Set<IIndexFile> handled) throws CoreException {
 		if (ifile == null) {
-			out.println(indent + ifl.getURI() + " is not indexed"); 
-		}
-		else {
+			writeUnresolvedTitle(out);
+			out.println(INDENT + ifl.getURI() + " is not indexed"); 
+		} else if (handled.add(ifile)) {
 			IIndexInclude[] includes = ifile.getIncludes();
 			for (IIndexInclude inc : includes) {
 				if (inc.isActive()) {
 					if (inc.isResolved()) {
-						outputUnresolvedIncludes(index, out, indent, inc.getIncludesLocation(), linkageID, handled);
-					}
-					else {
-						out.println(indent + "Unresolved inclusion: " + inc.getFullName() + " in file " +  
+						IIndexFile next = index.resolveInclude(inc);
+						outputUnresolvedIncludes(index, out, inc.getIncludesLocation(), next, handled);
+					} else {
+						writeUnresolvedTitle(out);
+						out.println(INDENT + "Unresolved inclusion: " + inc.getFullName() + " in file " +  
 								inc.getIncludedByLocation().getURI());
 					}
 				}
@@ -331,53 +350,85 @@ public class CreateParserLogAction implements IObjectActionDelegate {
 		}
 	}
 
-	private void output(PrintStream out, String indent, String[] list) {
-		for (String line : list) {
-			out.println(indent + line);
+	public void writeUnresolvedTitle(PrintStream out) {
+		if (!fWroteUnresolvedTitle) {
+			fWroteUnresolvedTitle= true;
+			out.println("Unresolved includes (from headers in index):");
 		}
 	}
 
-	private void output(PrintStream out, String indent, Map<String, String> definedSymbols, HashSet<String> reported) {
-		SortedMap<String, String> sorted= new TreeMap<String, String>(COMP_INSENSITIVE);
-		sorted.putAll(definedSymbols);
-		for (Entry<String, String> entry : sorted.entrySet()) {
-			final String macro = entry.getKey() + '=' + entry.getValue();
-			if (reported.add(macro)) {
-				out.println(indent + macro);
+	private void output(PrintStream out, String label, String[] list) {
+		if (list.length > 0) {
+			out.println(label);
+			for (String line : list) {
+				out.println(INDENT + line);
 			}
+			out.println();
 		}
 	}
-	
-	private void output(PrintStream out, String indent,	IASTPreprocessorMacroDefinition[] defs, HashSet<String> reported) {
-		SortedSet<String> macros= new TreeSet<String>(COMP_INSENSITIVE);
-		for (IASTPreprocessorMacroDefinition def : defs) {
-			macros.add(def.toString());
-		}
-		
-		for (String macro : macros) {
-			if (reported.add(macro)) {
-				out.println(indent + macro);
+
+	private void output(PrintStream out, String label, Map<String, String> definedSymbols, HashSet<String> reported) {
+		if (!definedSymbols.isEmpty()) {
+			out.println(label);
+
+			SortedMap<String, String> sorted= new TreeMap<String, String>(COMP_INSENSITIVE);
+			sorted.putAll(definedSymbols);
+			for (Entry<String, String> entry : sorted.entrySet()) {
+				final String macro = entry.getKey() + '=' + entry.getValue();
+				if (reported.add(macro)) {
+					out.println(INDENT + macro);
+				}
 			}
+			out.println();
 		}
 	}
 	
-	private void output(PrintStream out, String indent,	IASTProblem[] preprocessorProblems) {
-		for (IASTProblem problem : preprocessorProblems) {
-			out.println(indent + problem.getMessageWithLocation());
+	private void output(PrintStream out, String label, IASTPreprocessorMacroDefinition[] defs, HashSet<String> reported) {
+		if (defs.length > 0) {
+			out.println(label);
+			SortedSet<String> macros= new TreeSet<String>(COMP_INSENSITIVE);
+			for (IASTPreprocessorMacroDefinition def : defs) {
+				macros.add(def.toString());
+			}
+
+			for (String macro : macros) {
+				if (reported.add(macro)) {
+					out.println(INDENT + macro);
+				}
+			}
+			out.println();
 		}
 	}
 	
-	private void output(PrintStream out, String indent, List<IProblemBinding> list) {
-		for (IProblemBinding problem : list) {
-	        String file= problem.getFileName();
-	        int line = problem.getLineNumber();
-			out.println(indent + problem.getMessage() + " in file " + file + ':' + line); 
+	private void output(PrintStream out, String label, IASTProblem[] preprocessorProblems) {
+		if (preprocessorProblems.length > 0) {
+			out.println(label);
+			for (IASTProblem problem : preprocessorProblems) {
+				out.println(INDENT + problem.getMessageWithLocation());
+			}
+			out.println();
+		}
+	}
+		
+	private void output(PrintStream out, String label, IProblemBinding[] list) {
+		if (list.length > 0) {
+			out.println(label);
+			for (IProblemBinding problem : list) {
+				String file= problem.getFileName();
+				int line = problem.getLineNumber();
+				out.println(INDENT + problem.getMessage() + " in file " + file + ':' + line); 
+			}
+			out.println();
 		}
 	}
 
-	private void output(PrintStream out, List<Exception> list) {
-		for (Exception problem : list) {
-			problem.printStackTrace(out);
+	private void output(PrintStream out, String label, List<Exception> list) {
+		if (!list.isEmpty()) {
+			out.println(label);
+			for (Exception problem : list) {
+				problem.printStackTrace(out);
+			}
+			out.println();
 		}
 	}
 }
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/includebrowser/IBContentProvider.java b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/includebrowser/IBContentProvider.java
index 6c92fbf840e..96a8383a060 100644
--- a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/includebrowser/IBContentProvider.java
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/includebrowser/IBContentProvider.java
@@ -12,6 +12,8 @@ package org.eclipse.cdt.internal.ui.includebrowser;
 
 import java.util.ArrayList;
 import java.util.HashSet;
+import java.util.LinkedHashSet;
+import java.util.Set;
 
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IProgressMonitor;
@@ -102,7 +104,7 @@ public class IBContentProvider extends AsyncTreeContentProvider {
 					directiveFile= node.getRepresentedFile();
 				}
 				if (includes.length > 0) {
-					ArrayList<IBNode> result= new ArrayList<IBNode>(includes.length);
+					Set<IBNode> result= new LinkedHashSet<IBNode>(includes.length);
 					for (int i = 0; i < includes.length; i++) {
 						IIndexInclude include = includes[i];
 						try {
@@ -122,7 +124,8 @@ public class IBContentProvider extends AsyncTreeContentProvider {
 									include.getIncludedBy().getTimestamp());
 							newnode.setIsActiveCode(include.isActive());
 							newnode.setIsSystemInclude(include.isSystemInclude());
-							result.add(newnode);
+							if (!result.contains(newnode) || newnode.isActiveCode())
+								result.add(newnode);
 						} catch (CoreException e) {
 							CUIPlugin.log(e);
 						}