Objective-C ARC. Fixes a crash when checking for 'weak' propery 
whose base is not an expression. rdar://19053620

llvm-svn: 222570
diff --git a/clang/lib/Sema/ScopeInfo.cpp b/clang/lib/Sema/ScopeInfo.cpp
index 00d9982..63ef3b2 100644
--- a/clang/lib/Sema/ScopeInfo.cpp
+++ b/clang/lib/Sema/ScopeInfo.cpp
@@ -176,6 +176,8 @@
   // 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 {