objective-C: don't crash after diagnosing

using object subscripting without declaring objectForKeyedSubscript:
// rdar://13333205


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176539 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaExpr.cpp

@@ -547,7 +547,7 @@ ExprResult Sema::UsualUnaryConversions(Expr *E) {
   // First, convert to an r-value.
   ExprResult Res = DefaultFunctionArrayLvalueConversion(E);
   if (Res.isInvalid())
-    return Owned(E);
+    return ExprError();
   E = Res.take();
 
   QualType Ty = E->getType();
@@ -598,7 +598,7 @@ ExprResult Sema::DefaultArgumentPromotion(Expr *E) {
 
   ExprResult Res = UsualUnaryConversions(E);
   if (Res.isInvalid())
-    return Owned(E);
+    return ExprError();
   E = Res.take();
 
   // If this is a 'float' or '__fp16' (CVR qualified or typedef) promote to

test/SemaObjC/boxing-illegal.m

@@ -56,3 +56,20 @@ void testEnum(void *p) {
   box = @(ME_foo);
   box = @(*(enum ForwE*)p); // expected-error {{incomplete type 'enum ForwE' used in a boxed expression}}
 }
+
+// rdar://13333205
+@class NSMutableDictionary;
+
+@interface NSMutableArray
++ (NSMutableArray*) array;
+@end
+
+NSMutableDictionary* mBars;
+
+__attribute((objc_root_class)) @interface rdar13333205 @end
+
+@implementation rdar13333205
+- (void) insertBar:(id)preset ofKind:(id) kind atIndex:(int)index {
+  NSMutableArray* presetArray = mBars[kind] ?: [NSMutableArray array]; // expected-error {{expected method to read dictionary element not found on object of type 'NSMutableDictionary *'}}
+}
+@end