Eliminate an incomplete/incorrect attempt to provide support for C++0x

unrestricted unions, which ended up attempting to initialize objects
in a union (which CodeGen isn't prepared for). Fixes PR9683.

llvm-svn: 135027

clang/lib/Sema/SemaDeclCXX.cpp

@@ -2190,11 +2190,8 @@ static bool CollectFieldInitializer(Sema &SemaRef, BaseAndFieldInfo &Info,
         }
       }
 
-      // Fallthrough and construct a default initializer for the union as
-      // a whole, which can call its default constructor if such a thing exists
-      // (C++0x perhaps). FIXME: It's not clear that this is the correct
-      // behavior going forward with C++0x, when anonymous unions there are
-      // finalized, we should revisit this.
+      // FIXME: C++0x unrestricted unions might call a default constructor here.
+      return false;
     } else {
       // For structs, we simply descend through to initialize all members where
       // necessary.

clang/test/CodeGenCXX/anonymous-union-member-initializer.cpp

@@ -114,3 +114,19 @@ template <typename T> struct Foo {
   };
 };
 Foo<int> f;
+
+namespace PR9683 {
+  struct QueueEntry {
+    union {
+      struct {
+        void* mPtr;
+        union {
+          unsigned mSubmissionTag;
+        };
+      };
+      unsigned mValue;
+    };
+    QueueEntry() {}
+  };
+  QueueEntry QE;
+}