Objective-C ARC. Fixes a crash when checking for 'weak' propery

whose base is not an expression. rdar://19053620

llvm-svn: 222570

clang/lib/Sema/ScopeInfo.cpp

@@ -176,6 +176,8 @@ void FunctionScopeInfo::markSafeWeakUse(const Expr *E) {
   // Has this weak object been seen before?
   FunctionScopeInfo::WeakObjectUseMap::iterator Uses;
   if (const ObjCPropertyRefExpr *RefExpr = dyn_cast<ObjCPropertyRefExpr>(E)) {
+    if (!RefExpr->isObjectReceiver())
+      return;
     if (isa<OpaqueValueExpr>(RefExpr->getBase()))
      Uses = WeakObjectUses.find(WeakObjectProfileTy(RefExpr));
     else {

clang/test/SemaObjC/arc-repeated-weak.mm

@@ -425,3 +425,17 @@ void doubleLevelAccessIvar(Test *a, Test *b) {
 }
 @end
 
+// rdar://19053620
+@interface NSNull
++ (NSNull *)null;
+@end
+
+@interface INTF @end
+
+@implementation INTF
+- (void) Meth : (id) data
+{
+  data = data ?: NSNull.null;
+}
+@end
+