Don't use erased type for diagnostic output

checker/jtreg/nullness/MethodReceiverTypeErrorMessageTest.java

@@ -0,0 +1,20 @@
+/*
+ * @test
+ * @summary Test case for method receiver type in error message. If it is a non-raw type, it should be printed as such.
+ *
+ * @compile/fail/ref=MethodReceiverTypeErrorMessageTest.out -XDrawDiagnostics -processor org.checkerframework.checker.nullness.NullnessChecker MethodReceiverTypeErrorMessageTest.java
+ */
+public class MethodReceiverTypeErrorMessageTest<T> {
+
+    MethodReceiverTypeErrorMessageTest() {
+        foo();
+    }
+
+    void foo() {}
+
+    static class StringSpecialization extends MethodReceiverTypeErrorMessageTest<String> {
+        StringSpecialization() {
+            foo();
+        }
+    }
+}

checker/jtreg/nullness/MethodReceiverTypeErrorMessageTest.out

@@ -0,0 +1,7 @@
+MethodReceiverTypeErrorMessageTest.java:10:12: compiler.err.proc.messager: [method.invocation.invalid] call to foo() not allowed on the given receiver.
+found   : @UnderInitialization(MethodReceiverTypeErrorMessageTest.class) MethodReceiverTypeErrorMessageTest<T extends @Initialized Object>
+required: @Initialized MethodReceiverTypeErrorMessageTest<T extends @Initialized Object>
+MethodReceiverTypeErrorMessageTest.java:17:16: compiler.err.proc.messager: [method.invocation.invalid] call to foo() not allowed on the given receiver.
+found   : @UnderInitialization(MethodReceiverTypeErrorMessageTest.StringSpecialization.class) StringSpecialization
+required: @Initialized MethodReceiverTypeErrorMessageTest<@Initialized String>
+2 errors

framework/src/main/java/org/checkerframework/common/basetype/BaseTypeVisitor.java

@@ -3992,10 +3992,11 @@ protected void checkMethodInvocability(
         if (!skipReceiverSubtypeCheck(tree, erasedMethodReceiver, treeReceiver)) {
             // The diagnostic can be a bit misleading because the check is of the receiver but
             // `tree` is the entire method invocation (where the receiver might be implicit).
-            commonAssignmentCheckStartDiagnostic(erasedMethodReceiver, erasedTreeReceiver, tree);
+            commonAssignmentCheckStartDiagnostic(
+                    method.getReceiverType(), erasedTreeReceiver, tree);
             boolean success = typeHierarchy.isSubtype(erasedTreeReceiver, erasedMethodReceiver);
             commonAssignmentCheckEndDiagnostic(
-                    success, null, erasedMethodReceiver, erasedTreeReceiver, tree);
+                    success, null, method.getReceiverType(), erasedTreeReceiver, tree);
             if (!success) {
                 // Don't report the erased types because they show up with '</*RAW*/>' as type args.
                 reportMethodInvocabilityError(tree, treeReceiver, method.getReceiverType());