Issue a warning in odd case of instance method used

in a 'Class' receiver which is not a root instance
method.

llvm-svn: 70987

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -1096,6 +1096,8 @@ def ext_freestanding_complex : Extension<
 
 
 // Obj-c expressions
+def warn_root_inst_method_not_found : Warning<
+  "instance method %0 is being used on 'Class' which is not in the root class">;
 def warn_class_method_not_found : Warning<
   "method %objcclass0 not found (return type defaults to 'id')">;
 def warn_inst_method_not_found : Warning<

clang/lib/Sema/SemaExprObjC.cpp

@@ -529,8 +529,17 @@ Sema::ExprResult Sema::ActOnInstanceMessage(ExprTy *receiver, Selector Sel,
       if (!isSelfExpr(RExpr)) {
         Method = LookupFactoryMethodInGlobalPool(Sel, SourceRange(lbrac,rbrac));
         if (!Method) {
+          // If no class (factory) method was found, check if an _instance_
+          // method of the same name exists in the root class only.
           Method = LookupInstanceMethodInGlobalPool(
                                    Sel, SourceRange(lbrac,rbrac));
+          if (Method)
+              if (const ObjCInterfaceDecl *ID =
+                dyn_cast<ObjCInterfaceDecl>(Method->getDeclContext())) {
+              if (ID->getSuperClass())
+                Diag(lbrac, diag::warn_root_inst_method_not_found)
+                  << Sel << SourceRange(lbrac, rbrac);
+            }
         }
       }
     }

clang/test/SemaObjC/inst-method-lookup-in-root.m

@@ -0,0 +1,27 @@
+// RUN: clang-cc  -fsyntax-only -verify %s
+
+@protocol P
+- (id) inst_in_proto;
+@end
+
+@interface Object <P>
+- (id) inst_in_root;
+@end
+
+@interface Base
+@end
+
+@interface Derived: Base
+- (id)starboard;
+@end
+
+void foo(void) {
+  Class receiver;
+
+  [Derived starboard]; // expected-warning {{method '+starboard' not found}}
+
+  [receiver starboard]; // expected-warning {{instance method 'starboard' is being used on 'Class'}}
+  [receiver inst_in_root]; // Ok!
+  [receiver inst_in_proto]; // Ok!
+}
+