__weak ivar need not warn.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@59743 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaDeclAttr.cpp

@@ -556,7 +556,7 @@ static void HandleObjCGCAttr(Decl *d, const AttributeList &Attr, Sema &S) {
   
   ObjCGCAttr::GCAttrTypes type;
   if (Attr.getParameterName()->isStr("weak")) {
-    if (isa<FieldDecl>(d))
+    if (isa<FieldDecl>(d) && !isa<ObjCIvarDecl>(d))
       S.Diag(Attr.getLoc(), diag::warn_attribute_weak_on_field);
     type = ObjCGCAttr::Weak;
   }

test/SemaObjC/warn-weak-field.m

@@ -5,6 +5,17 @@ struct S {
 	__strong id p1;
 };
 
+@interface I
+{
+   __weak id w;	// OK
+   __strong id LHS;
+}
+- (void) foo;
+@end
+@implementation I
+- (void) foo { w = 0; LHS = w; }
+@end
+
 int main ()
 {
 	struct I {