Bug 387612 - Unreachable catch block...exception is never thrown from

the try

2 files changed, 178 insertions, 4 deletions

diff --git a/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/TryStatementTest.java b/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/TryStatementTest.java
index 3fff7df..bcef02a 100644
--- a/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/TryStatementTest.java
+++ b/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/TryStatementTest.java
@@ -9,6 +9,7 @@
  *     IBM Corporation - initial API and implementation
  *     Stephan Herrmann - Contribution for
  *								bug 345305 - [compiler][null] Compiler misidentifies a case of "variable can only be null"
+ *								bug 387612 - Unreachable catch block...exception is never thrown from the try
  *******************************************************************************/
 package org.eclipse.jdt.core.tests.compiler.regression;
 
@@ -25,7 +26,7 @@ import junit.framework.Test;
 public class TryStatementTest extends AbstractRegressionTest {
 
 static {
-//	TESTS_NAMES = new String[] { "test074" };
+//	TESTS_NAMES = new String[] { "testBug387612" };
 //	TESTS_NUMBERS = new int[] { 74, 75 };
 //	TESTS_RANGE = new int[] { 11, -1 };
 }
@@ -5990,6 +5991,141 @@ public void test074() {
 		});
 }
 
+// Bug 387612 - Unreachable catch block...exception is never thrown from the try
+// redundant exception in throws must not confuse downstream analysis
+public void testBug387612() {
+	String serialUID = "private static final long serialVersionUID=1L;";
+	runNegativeTest(
+		new String[] {
+			"E.java",
+			"public class E extends Exception {"+serialUID+"}\n",
+			"E1.java",
+			"public class E1 extends E {"+serialUID+"}\n",
+			"E2.java",
+			"public class E2 extends E {"+serialUID+"}\n",
+			"E3.java",
+			"public class E3 extends E {"+serialUID+"}\n",
+			"A.java",
+			"interface A {\n" +
+			"    void foo(String a1, String a2) throws E1, E;\n" +
+			"}\n",
+			"B.java",
+			"interface B extends A {\n" +
+			"    void foo(String a1, String a2) throws E;\n" +
+			"}\n",
+			"Client.java",
+			"public class Client {\n" +
+			"    void test() {\n" +
+			"        B b = new B() {\n" +
+			"            public void foo(String a1, String a2) {}\n" +
+			"        };\n" +
+			"        try {\n" +
+			"            b.foo(null, null);\n" +
+			"        }\n" +
+			"        catch (E1 e) {}\n" +
+			"        catch (E2 e) {}\n" +
+			"    }\n" +
+			"}\n",
+		},
+		"----------\n" + 
+		"1. ERROR in Client.java (at line 7)\n" + 
+		"	b.foo(null, null);\n" + 
+		"	^^^^^^^^^^^^^^^^^\n" + 
+		"Unhandled exception type E\n" + 
+		"----------\n");
+}
+
+// Bug 387612 - Unreachable catch block...exception is never thrown from the try
+// - changed order in redundant 'throws' clause.
+public void testBug387612b() {
+	String serialUID = "private static final long serialVersionUID=1L;";
+	runNegativeTest(
+		new String[] {
+			"E.java",
+			"public class E extends Exception {"+serialUID+"}\n",
+			"E1.java",
+			"public class E1 extends E {"+serialUID+"}\n",
+			"E2.java",
+			"public class E2 extends E {"+serialUID+"}\n",
+			"E3.java",
+			"public class E3 extends E {"+serialUID+"}\n",
+			"A.java",
+			"interface A {\n" +
+			"    void foo(String a1, String a2) throws E, E1;\n" +
+			"}\n",
+			"B.java",
+			"interface B extends A {\n" +
+			"    void foo(String a1, String a2) throws E;\n" +
+			"}\n",
+			"Client.java",
+			"public class Client {\n" +
+			"    void test() {\n" +
+			"        B b = new B() {\n" +
+			"            public void foo(String a1, String a2) {}\n" +
+			"        };\n" +
+			"        try {\n" +
+			"            b.foo(null, null);\n" +
+			"        }\n" +
+			"        catch (E1 e) {}\n" +
+			"        catch (E2 e) {}\n" +
+			"    }\n" +
+			"}\n",
+		},
+		"----------\n" + 
+		"1. ERROR in Client.java (at line 7)\n" + 
+		"	b.foo(null, null);\n" + 
+		"	^^^^^^^^^^^^^^^^^\n" + 
+		"Unhandled exception type E\n" + 
+		"----------\n");
+}
+
+// Bug 387612 - Unreachable catch block...exception is never thrown from the try
+// interface with redundant exceptions in throws is read from class file.
+public void testBug387612c() {
+	String serialUID = "private static final long serialVersionUID=1L;";
+	runConformTest(
+		new String[] {
+			"E.java",
+			"public class E extends Exception {"+serialUID+"}\n",
+			"E1.java",
+			"public class E1 extends E {"+serialUID+"}\n",
+			"E2.java",
+			"public class E2 extends E {"+serialUID+"}\n",
+			"A.java",
+			"interface A {\n" +
+			"    void foo(String a1, String a2) throws E1, E;\n" +
+			"}\n",
+			"B.java",
+			"interface B extends A {\n" +
+			"    void foo(String a1, String a2) throws E;\n" +
+			"}\n"
+		});
+	runNegativeTest(
+		new String[] {
+			"Client.java",
+			"public class Client {\n" +
+			"    void test() {\n" +
+			"        B b = new B() {\n" +
+			"            public void foo(String a1, String a2) {}\n" +
+			"        };\n" +
+			"        try {\n" +
+			"            b.foo(null, null);\n" +
+			"        }\n" +
+			"        catch (E1 e) {}\n" +
+			"        catch (E2 e) {}\n" +
+			"    }\n" +
+			"}\n",
+		},
+		"----------\n" + 
+		"1. ERROR in Client.java (at line 7)\n" + 
+		"	b.foo(null, null);\n" + 
+		"	^^^^^^^^^^^^^^^^^\n" + 
+		"Unhandled exception type E\n" + 
+		"----------\n",
+		null,
+		false/*shouldFlush*/);
+}
+
 public static Class testClass() {
 	return TryStatementTest.class;
 }
diff --git a/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/lookup/Scope.java b/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/lookup/Scope.java
index d3f5cbe..3d8930d 100644
--- a/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/lookup/Scope.java
+++ b/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/lookup/Scope.java
@@ -11,7 +11,9 @@
  * 
  * Contributors:
  *     IBM Corporation - initial API and implementation
- *     Stephan Herrmann - Contribution for bug 186342 [compiler][null] Using annotations for null checking
+ *     Stephan Herrmann - Contributions for
+ *	 							bug 186342 - [compiler][null] Using annotations for null checking
+ *								bug 387612 - Unreachable catch block...exception is never thrown from the try
  *******************************************************************************/
 package org.eclipse.jdt.internal.compiler.lookup;
 
@@ -3996,13 +3998,14 @@ public abstract class Scope {
 										mostSpecificExceptions = current.thrownExceptions;
 									}
 									int mostSpecificLength = mostSpecificExceptions.length;
-									int nextLength = next.thrownExceptions.length;
+									ReferenceBinding[] nextExceptions = getFilteredExceptions(next);
+									int nextLength = nextExceptions.length;
 									SimpleSet temp = new SimpleSet(mostSpecificLength);
 									boolean changed = false;
 									nextException : for (int t = 0; t < mostSpecificLength; t++) {
 										ReferenceBinding exception = mostSpecificExceptions[t];
 										for (int s = 0; s < nextLength; s++) {
-											ReferenceBinding nextException = next.thrownExceptions[s];
+											ReferenceBinding nextException = nextExceptions[s];
 											if (exception.isCompatibleWith(nextException)) {
 												temp.add(exception);
 												continue nextException;
@@ -4035,6 +4038,41 @@ public abstract class Scope {
 		return new ProblemMethodBinding(visible[0], visible[0].selector, visible[0].parameters, ProblemReasons.Ambiguous);
 	}
 
+	private ReferenceBinding[] getFilteredExceptions(MethodBinding method) {
+		// http://bugs.eclipse.org/387612 - Unreachable catch block...exception is never thrown from the try
+		// Need to filter redundant exceptions within the same throws clause.
+		// In this filtering the *most general* exception wins in order to capture all possible exceptions
+		// that could be thrown by the given method.
+		ReferenceBinding[] allExceptions = method.thrownExceptions;
+		int length = allExceptions.length;
+		if (length < 2) return allExceptions;
+		ReferenceBinding[] filteredExceptions = new ReferenceBinding[length];
+		int count = 0;
+		currents: for (int i = 0; i < length; i++) {
+			ReferenceBinding currentException = allExceptions[i];
+			for (int j = 0; j < length; j++) {
+				if (i == j) continue;
+				if (currentException == allExceptions[j]) {
+					// duplicate same exception
+					if (i < j) 
+						break; // take only the first occurrence
+					else
+						continue currents; // skip
+				}
+				if (currentException.isCompatibleWith(allExceptions[j])) {
+					continue currents; // skip
+				}
+			}
+			filteredExceptions[count++] = currentException;
+		}
+		if (count != length) {
+			ReferenceBinding[] tmp = new ReferenceBinding[count];
+			System.arraycopy(filteredExceptions, 0, tmp,  0, count);
+			return tmp;
+		}
+		return allExceptions;
+	}
+
 	public final ClassScope outerMostClassScope() {
 		ClassScope lastClassScope = null;
 		Scope scope = this;