Index: src/org/eclipse/jdt/core/tests/compiler/regression/AmbiguousMethodTest.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/AmbiguousMethodTest.java,v
retrieving revision 1.42
diff -u -r1.42 AmbiguousMethodTest.java
--- src/org/eclipse/jdt/core/tests/compiler/regression/AmbiguousMethodTest.java	30 Apr 2007 19:03:58 -0000	1.42
+++ src/org/eclipse/jdt/core/tests/compiler/regression/AmbiguousMethodTest.java	14 May 2007 19:34:46 -0000
@@ -1984,4 +1984,22 @@
 		},
 		"");
 }
+// https://bugs.eclipse.org/bugs/show_bug.cgi?id=186382
+public void test057() {
+	this.runConformTest(
+		new String[] {
+			"X.java",
+			"public class X extends Y {\n" + 
+			"	@Override <T4, G4 extends I<T4>> T4 foo(G4 g) { return super.foo(g); }\n" + 
+			"}\n" + 
+			"class Y extends Z {\n" + 
+			"	@Override <T3, G3 extends I<T3>> T3 foo(G3 g) { return super.foo(g); }\n" + 
+			"}\n" + 
+			"class Z {\n" + 
+			"	<T2, G2 extends I<T2>> T2 foo(G2 g) { return null; }\n" + 
+			"}\n" + 
+			"interface I<T1> {}"
+		},
+		"");
+}
 }
Index: compiler/org/eclipse/jdt/internal/compiler/lookup/MethodBinding.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/lookup/MethodBinding.java,v
retrieving revision 1.91
diff -u -r1.91 MethodBinding.java
--- compiler/org/eclipse/jdt/internal/compiler/lookup/MethodBinding.java	12 Apr 2007 22:39:50 -0000	1.91
+++ compiler/org/eclipse/jdt/internal/compiler/lookup/MethodBinding.java	14 May 2007 19:34:49 -0000
@@ -299,18 +299,20 @@
 	return false;
 }
 MethodBinding computeSubstitutedMethod(MethodBinding method, LookupEnvironment env) {
-	TypeVariableBinding[] vars = this.typeVariables;
-	TypeVariableBinding[] vars2 = method.typeVariables;
-	if (vars.length != vars2.length)
+	int length = this.typeVariables.length;
+	TypeVariableBinding[] vars = method.typeVariables;
+	if (length != vars.length)
 		return null;
-	for (int v = vars.length; --v >= 0;)
-		if (!vars[v].isInterchangeableWith(env, vars2[v]))
-			return null;
 
 	// must substitute to detect cases like:
 	//   <T1 extends X<T1>> void dup() {}
 	//   <T2 extends X<T2>> Object dup() {return null;}
-	return env.createParameterizedGenericMethod(method, vars);
+	ParameterizedGenericMethodBinding substitute =
+		env.createParameterizedGenericMethod(method, this.typeVariables);
+	for (int i = 0; i < length; i++)
+		if (!this.typeVariables[i].isInterchangeableWith(vars[i], substitute))
+			return null;
+	return substitute;
 }
 /*
  * declaringUniqueKey dot selector genericSignature
Index: compiler/org/eclipse/jdt/internal/compiler/lookup/TypeVariableBinding.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/lookup/TypeVariableBinding.java,v
retrieving revision 1.59
diff -u -r1.59 TypeVariableBinding.java
--- compiler/org/eclipse/jdt/internal/compiler/lookup/TypeVariableBinding.java	16 Mar 2007 18:28:58 -0000	1.59
+++ compiler/org/eclipse/jdt/internal/compiler/lookup/TypeVariableBinding.java	14 May 2007 19:34:49 -0000
@@ -297,41 +297,23 @@
 	 * the same bounds, providing one is substituted with the other: <T1 extends
 	 * List<T1>> is interchangeable with <T2 extends List<T2>>.
 	 */
-	public boolean isInterchangeableWith(final LookupEnvironment environment, final TypeVariableBinding otherVariable) {
+	public boolean isInterchangeableWith(TypeVariableBinding otherVariable, ParameterizedGenericMethodBinding substitute) {
 		if (this == otherVariable)
 			return true;
 		int length = this.superInterfaces.length;
 		if (length != otherVariable.superInterfaces.length)
 			return false;
 
-		identical: {
-			if (this.superclass != otherVariable.superclass) {
-				if (this.superclass.erasure() != otherVariable.superclass.erasure())
-					return false; // no way it can match after substitution
-				break identical;
-			}
-			for (int i = 0; i < length; i++) {
-				if (this.superInterfaces[i] != otherVariable.superInterfaces[i]) {
-					if (this.superInterfaces[i].erasure() != otherVariable.superInterfaces[i].erasure())
-						return false; // no way it can match after substitution
-					break identical;
-				}
-			}
-			return true;
-		}
-		// need substitutions
-		Substitution subst = new Substitution() {
-			public LookupEnvironment environment() { return environment; }
-			public boolean isRawSubstitution() { return false; }
-			public TypeBinding substitute(TypeVariableBinding typeVariable) {
-				return typeVariable == otherVariable ? TypeVariableBinding.this : typeVariable;
-			}
-		};
-		if (this.superclass != Scope.substitute(subst, otherVariable.superclass))
+		if (this.superclass != Scope.substitute(substitute, otherVariable.superclass))
 			return false;
-		for (int i = 0; i < length; i++)
-			if (this.superInterfaces[i] != Scope.substitute(subst, otherVariable.superInterfaces[i]))
-				return false;
+
+		next : for (int i = 0; i < length; i++) {
+			TypeBinding superType = Scope.substitute(substitute, otherVariable.superInterfaces[i]);
+			for (int j = 0; j < length; j++)
+				if (superType == this.superInterfaces[j])
+					continue next;
+			return false; // not a match
+		}
 		return true;
 	}