[Bug 340300] Fix parallel make when using pre-build steps

Pre-build will always run in parallel to compilation of source files
unless each and every source file depends on pre-build. Also, when
parallel build was enabled, the "Make build target" under "Workbench
Build Behavior" was ignored. Instead of doing make -j all, Eclipse ran
make -j pre-build main-build. While the intentions are good, make will
attempt to build pre-build and main-build in parallel for previous
stated reasons.

This patch changes two things:

1. Eclipse will consistently respect the "Workbench Build Behavior" for
both single- and multi-process build.
2. The generated makefile is changed to guarantee pre-build is run
first.

   Changed from

       all: pre-build main-build

   to

       all:
           $(MAKE) --no-print-directory pre-build
           $(MAKE) --no-print-directory main-build

Change-Id: Icf3a1057ee3b3cc8a04a433820492a4f469e17dd
Signed-off-by: Morten Kristiansen <millibit@gmail.com>

2 files changed, 23 insertions, 44 deletions

diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/ExternalBuildRunner.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/ExternalBuildRunner.java
index fd54bf98905..41dab02d436 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/ExternalBuildRunner.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/core/ExternalBuildRunner.java
@@ -160,43 +160,22 @@ public class ExternalBuildRunner extends AbstractBuildRunner {
 	}
 
 	protected String[] getTargets(int kind, IBuilder builder) {
-		String targetsArray[] = null;
-
-		if(kind != IncrementalProjectBuilder.CLEAN_BUILD && !builder.isCustomBuilder() && builder.isManagedBuildOn()){
-			IConfiguration cfg = builder.getParent().getParent();
-			String preBuildStep = cfg.getPrebuildStep();
-			try {
-				preBuildStep = ManagedBuildManager.getBuildMacroProvider().resolveValueToMakefileFormat(
-						preBuildStep,
-						"", //$NON-NLS-1$
-						" ", //$NON-NLS-1$
-						IBuildMacroProvider.CONTEXT_CONFIGURATION,
-						cfg);
-			} catch (BuildMacroException e) {
-			}
-
-			if(preBuildStep != null && preBuildStep.length() != 0){
-				targetsArray = new String[]{"pre-build", "main-build"}; //$NON-NLS-1$ //$NON-NLS-2$
-			}
+		String targets = ""; //$NON-NLS-1$
+		switch (kind) {
+		case IncrementalProjectBuilder.AUTO_BUILD :
+			targets = builder.getAutoBuildTarget();
+			break;
+		case IncrementalProjectBuilder.INCREMENTAL_BUILD : // now treated as the same!
+		case IncrementalProjectBuilder.FULL_BUILD :
+			targets = builder.getIncrementalBuildTarget();
+			break;
+		case IncrementalProjectBuilder.CLEAN_BUILD :
+			targets = builder.getCleanBuildTarget();
+			break;
 		}
 
-		if(targetsArray == null){
-			String targets = ""; //$NON-NLS-1$
-			switch (kind) {
-				case IncrementalProjectBuilder.AUTO_BUILD :
-					targets = builder.getAutoBuildTarget();
-					break;
-				case IncrementalProjectBuilder.INCREMENTAL_BUILD : // now treated as the same!
-				case IncrementalProjectBuilder.FULL_BUILD :
-					targets = builder.getIncrementalBuildTarget();
-					break;
-				case IncrementalProjectBuilder.CLEAN_BUILD :
-					targets = builder.getCleanBuildTarget();
-					break;
-			}
+		String targetsArray[] = CommandLineUtil.argumentsToArray(targets);
 
-			targetsArray = CommandLineUtil.argumentsToArray(targets);
-		}
 
 		return targetsArray;
 	}
diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/makegen/gnu/GnuMakefileGenerator.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/makegen/gnu/GnuMakefileGenerator.java
index 67fbf4825a0..28cba267ac4 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/makegen/gnu/GnuMakefileGenerator.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/makegen/gnu/GnuMakefileGenerator.java
@@ -1348,8 +1348,10 @@ public class GnuMakefileGenerator implements IManagedBuilderMakefileGenerator2 {
 			// and neither conditions apply if we are building for it ....
 		}
 */
-        // If a prebuild step exists, redefine the all target to be
-		// all: {pre-build} main-build
+		// If a prebuild step exists, redefine the all target to be
+		// all: 
+		//     $(MAKE) pre-build
+		//     $(MAKE) main-build
 		// and then reset the "traditional" all target to main-build
 		// This will allow something meaningful to happen if the generated
 		// makefile is
@@ -1361,17 +1363,15 @@ public class GnuMakefileGenerator implements IManagedBuilderMakefileGenerator2 {
 			// Add the comment for the "All" target
 			buffer.append(COMMENT_SYMBOL).append(WHITESPACE).append(ManagedMakeMessages.getResourceString(ALL_TARGET)).append(NEWLINE);
 
-			buffer.append(defaultTarget).append(WHITESPACE);
-			buffer.append(PREBUILD).append(WHITESPACE);
-
-			// Reset defaultTarget for now and for subsequent use, below
-			defaultTarget = MAINBUILD;
-			buffer.append(defaultTarget);
+			// Invoke make multiple times to ensure pre-build is executed before main-build
+			buffer.append(defaultTarget).append(NEWLINE);
+			buffer.append(TAB).append(MAKE).append(WHITESPACE).append(NO_PRINT_DIR).append(WHITESPACE).append(PREBUILD).append(NEWLINE);
+			buffer.append(TAB).append(MAKE).append(WHITESPACE).append(NO_PRINT_DIR).append(WHITESPACE).append(MAINBUILD).append(NEWLINE);
+			buffer.append(NEWLINE);
 
 			// Update the defaultTarget, main-build, by adding a colon, which is
 			// needed below
-			defaultTarget = defaultTarget.concat(COLON);
-			buffer.append(NEWLINE).append(NEWLINE);
+			defaultTarget = MAINBUILD.concat(COLON);
 
 			// Add the comment for the "main-build" target
 			buffer.append(COMMENT_SYMBOL).append(WHITESPACE).append(ManagedMakeMessages.getResourceString(MAINBUILD_TARGET)).append(NEWLINE);