### Eclipse Workspace Patch 1.0
#P org.eclipse.jdt.core.tests.compiler
Index: src/org/eclipse/jdt/core/tests/compiler/regression/GenericTypeTest.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/GenericTypeTest.java,v
retrieving revision 1.611
diff -u -r1.611 GenericTypeTest.java
--- src/org/eclipse/jdt/core/tests/compiler/regression/GenericTypeTest.java	13 Apr 2007 14:55:45 -0000	1.611
+++ src/org/eclipse/jdt/core/tests/compiler/regression/GenericTypeTest.java	20 Apr 2007 19:10:15 -0000
@@ -11170,7 +11170,7 @@
 			                ^
 			 */
 	}
-	public void test0384() {
+	public void test0384a() {
 		this.runConformTest(
 			new String[] {
 				"X.java",
@@ -11186,6 +11186,8 @@
 				"}\n"
 			},
 			"");
+	}
+	public void test0384b() {
 		this.runNegativeTest(
 			new String[] {
 				"X.java",
Index: src/org/eclipse/jdt/core/tests/compiler/regression/MethodVerifyTest.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/MethodVerifyTest.java,v
retrieving revision 1.121
diff -u -r1.121 MethodVerifyTest.java
--- src/org/eclipse/jdt/core/tests/compiler/regression/MethodVerifyTest.java	28 Mar 2007 04:52:16 -0000	1.121
+++ src/org/eclipse/jdt/core/tests/compiler/regression/MethodVerifyTest.java	20 Apr 2007 19:10:16 -0000
@@ -7544,4 +7544,183 @@
 		"Type safety: The return type Enum<?> for foo() from the type X.B needs unchecked conversion to conform to U from the type X.A<T>\n" + 
 		"----------\n");
 }
+// https://bugs.eclipse.org/bugs/show_bug.cgi?id=180789
+public void test128() {
+	this.runNegativeTest(
+		new String[] {
+			"X.java",
+			"interface I<U, V> {\n" + 
+			"  U foo(Object o, V v);\n" + 
+			"}\n" + 
+			"public class X<U, V> implements I<U, V> {\n" + 
+			"  public Object foo(Object o, Object v) { return null; }\n" + 
+			"}\n"
+		},
+		"----------\n" + 
+		"1. WARNING in X.java (at line 5)\n" + 
+		"	public Object foo(Object o, Object v) { return null; }\n" + 
+		"	       ^^^^^^\n" + 
+		"Type safety: The return type Object for foo(Object, Object) from the type X<U,V> needs unchecked conversion to conform to U from the type I<U,V>\n" + 
+		"----------\n"
+	);
+}
+// https://bugs.eclipse.org/bugs/show_bug.cgi?id=180789
+// variant - Object is not a subtype of Z
+public void test129() {
+	this.runNegativeTest(
+		new String[] {
+			"X.java",
+			"interface I<U, V> {\n" + 
+			"  U foo(Object o, V v);\n" + 
+			"}\n" + 
+			"public class X<U extends Z, V> implements I<U, V> {\n" + 
+			"  public Object foo(Object o, Object v) { return null; }\n" + 
+			"}\n" + 
+			"class Z {}"
+		},
+		"----------\n" + 
+		"1. ERROR in X.java (at line 5)\n" + 
+		"	public Object foo(Object o, Object v) { return null; }\n" + 
+		"	       ^^^^^^\n" + 
+		"The return type is incompatible with I<U,V>.foo(Object, V)\n" + 
+		"----------\n"
+	);
+}
+// https://bugs.eclipse.org/bugs/show_bug.cgi?id=180789
+// ** variant - Z<Object> is not a subtype of Z<U>, and |Z<U>| = Z, not Z<Object>
+public void test130() {
+	this.runNegativeTest(
+		new String[] {
+			"X.java",
+			"interface I<U, V> {\n" + 
+			"  Z<U> foo(Object o, V v);\n" + 
+			"}\n" + 
+			"public class X<U, V> implements I<U, V> {\n" + 
+			"  public Z<Object> foo(Object o, Object v) { return null; }\n" + 
+			"}\n" + 
+			"class Z<T> {}"
+		},
+		"----------\n" + 
+		"1. ERROR in X.java (at line 5)\n" + 
+		"	public Z<Object> foo(Object o, Object v) { return null; }\n" + 
+		"	       ^^^^^^^^^\n" + 
+		"The return type is incompatible with I<U,V>.foo(Object, V)\n" + 
+		"----------\n"
+	);
+}
+// https://bugs.eclipse.org/bugs/show_bug.cgi?id=180789
+// variant - two interfaces
+public void test131() {
+	this.runNegativeTest(
+		new String[] {
+			"X.java",
+			"interface I<U, V> {\n" + 
+			"  U foo();\n" + 
+			"  U foo(Object o, V v);\n" + 
+			"}\n" + 
+			"interface X<U, V> extends I<U, V> {\n" + 
+			"  Object foo();\n" + 
+			"  Object foo(Object o, Object v);\n" + 
+			"}\n"
+		},
+		"----------\n" + 
+		"1. ERROR in X.java (at line 6)\n" + 
+		"	Object foo();\n" + 
+		"	^^^^^^\n" + 
+		"The return type is incompatible with I<U,V>.foo()\n" + 
+		"----------\n" + 
+		"2. WARNING in X.java (at line 7)\n" + 
+		"	Object foo(Object o, Object v);\n" + 
+		"	^^^^^^\n" + 
+		"Type safety: The return type Object for foo(Object, Object) from the type X<U,V> needs unchecked conversion to conform to U from the type I<U,V>\n" + 
+		"----------\n"
+	);
+}
+// https://bugs.eclipse.org/bugs/show_bug.cgi?id=180789
+// variant - type identity vs type equivalence
+public void test132() {
+	this.runNegativeTest(
+		new String[] {
+			"X.java",
+			"interface I<U> {\n" + 
+			"  U foo(I<?> p);\n" + 
+			"  U foo2(I<? extends Object> p);\n" + 
+			"}\n" + 
+			"public class X<U> implements I<U> {\n" + 
+			"  public Object foo(I<? extends Object> p) { return null; }\n" + 
+			"  public Object foo2(I<?> p) { return null; }\n" + 
+			"}\n"
+		},
+		"----------\n" + 
+		"1. ERROR in X.java (at line 6)\n" + 
+		"	public Object foo(I<? extends Object> p) { return null; }\n" + 
+		"	       ^^^^^^\n" + 
+		"The return type is incompatible with I<U>.foo(I<?>)\n" + 
+		"----------\n" + 
+		"2. ERROR in X.java (at line 7)\n" + 
+		"	public Object foo2(I<?> p) { return null; }\n" + 
+		"	       ^^^^^^\n" + 
+		"The return type is incompatible with I<U>.foo2(I<? extends Object>)\n" + 
+		"----------\n"
+	);
+}
+// https://bugs.eclipse.org/bugs/show_bug.cgi?id=180789
+// variant - if we detect a return type incompatibility, then skip any @Override errors 
+public void test133() {
+	this.runNegativeTest(
+		new String[] {
+			"A.java",
+			"class A<U> {\n" + 
+			"  U foo() { return null; }\n" + 
+			"  U foo(U one) { return null; }\n" + 
+			"  U foo(U one, U two) { return null; }\n" + 
+			"}\n" + 
+			"class B<U> extends A<U> {\n" + 
+			"  @Override // does not override error\n" + 
+			"  Object foo() { return null; } // cannot override foo(), incompatible return type error\n" +
+			"  @Override // does not override error\n" + 
+			"  Object foo(Object one) { return null; } // unchecked conversion warning\n" +
+			"  @Override // does not override error\n" + 
+			"  Object foo(Object one, U two) { return null; }\n" +
+			"}\n" + 
+			"class C<U> extends A<U> {\n" + 
+			"  @Override // does not override error\n" + 
+			"  Object foo(U one) { return null; } // cannot override foo(U), incompatible return type error\n" +
+			"  @Override // does not override error\n" + 
+			"  Object foo(U one, U two) { return null; } // cannot override foo(U), incompatible return type error\n" +
+			"}"
+		},
+		"----------\n" + 
+		"1. ERROR in A.java (at line 8)\n" + 
+		"	Object foo() { return null; } // cannot override foo(), incompatible return type error\n" + 
+		"	^^^^^^\n" + 
+		"The return type is incompatible with A<U>.foo()\n" + 
+		"----------\n" + 
+		"2. WARNING in A.java (at line 10)\n" + 
+		"	Object foo(Object one) { return null; } // unchecked conversion warning\n" + 
+		"	^^^^^^\n" + 
+		"Type safety: The return type Object for foo(Object) from the type B<U> needs unchecked conversion to conform to U from the type A<U>\n" + 
+		"----------\n" + 
+		"3. ERROR in A.java (at line 12)\n" + 
+		"	Object foo(Object one, U two) { return null; }\n" + 
+		"	       ^^^^^^^^^^^^^^^^^^^^^^\n" + 
+		"Name clash: The method foo(Object, U) of type B<U> has the same erasure as foo(U, U) of type A<U> but does not override it\n" + 
+		"----------\n" + 
+		"4. ERROR in A.java (at line 12)\n" + 
+		"	Object foo(Object one, U two) { return null; }\n" + 
+		"	       ^^^^^^^^^^^^^^^^^^^^^^\n" + 
+		"The method foo(Object, U) of type B<U> must override a superclass method\n" + 
+		"----------\n" + 
+		"5. ERROR in A.java (at line 16)\n" + 
+		"	Object foo(U one) { return null; } // cannot override foo(U), incompatible return type error\n" + 
+		"	^^^^^^\n" + 
+		"The return type is incompatible with A<U>.foo(U)\n" + 
+		"----------\n" + 
+		"6. ERROR in A.java (at line 18)\n" + 
+		"	Object foo(U one, U two) { return null; } // cannot override foo(U), incompatible return type error\n" + 
+		"	^^^^^^\n" + 
+		"The return type is incompatible with A<U>.foo(U, U)\n" + 
+		"----------\n"
+	);
+}
 }
#P org.eclipse.jdt.core
Index: compiler/org/eclipse/jdt/internal/compiler/lookup/MethodVerifier15.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/lookup/MethodVerifier15.java,v
retrieving revision 1.74
diff -u -r1.74 MethodVerifier15.java
--- compiler/org/eclipse/jdt/internal/compiler/lookup/MethodVerifier15.java	17 Apr 2007 14:34:08 -0000	1.74
+++ compiler/org/eclipse/jdt/internal/compiler/lookup/MethodVerifier15.java	20 Apr 2007 19:10:18 -0000
@@ -769,6 +769,18 @@
 	return copy;
 }
 boolean reportIncompatibleReturnTypeError(MethodBinding currentMethod, MethodBinding inheritedMethod) {
+	// JLS 3 §8.4.5: more are accepted, with an unchecked conversion
+	if (currentMethod.returnType == inheritedMethod.returnType.erasure()) {
+		TypeBinding[] currentParams = currentMethod.parameters;
+		TypeBinding[] inheritedParams = inheritedMethod.parameters;
+		for (int i = 0, l = currentParams.length; i < l; i++) {
+			if (!areTypesEqual(currentParams[i], inheritedParams[i])) {
+				problemReporter(currentMethod).unsafeReturnTypeOverride(currentMethod, inheritedMethod, this.type);
+				return false;
+			}
+		}
+	}
+
 	if (currentMethod.typeVariables == Binding.NO_TYPE_VARIABLES
 		&& inheritedMethod.original().typeVariables != Binding.NO_TYPE_VARIABLES
 		&& currentMethod.returnType.erasure().findSuperTypeWithSameErasure(inheritedMethod.returnType.erasure()) != null) {