Fix an assertion when initializing a union using a member initializer. (We weren't casting from the union type to the initializer type correctly).

llvm-svn: 80837

clang/lib/CodeGen/CGCXX.cpp

@@ -1658,7 +1658,8 @@ void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD) {
         else {
           // Initializing an anonymous union data member.
           FieldDecl *anonMember = Member->getAnonUnionMember();
-          LHS = EmitLValueForField(LHS.getAddress(), anonMember, false, 0);
+          LHS = EmitLValueForField(LHS.getAddress(), anonMember, 
+                                   /*IsUnion=*/true, 0);
           FieldType = anonMember->getType();
         }
       }

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

@@ -0,0 +1,12 @@
+// RUN: clang-cc -emit-llvm -o - %s
+
+struct A {
+  union {
+    int a;
+    void* b;
+  };
+  
+  A() : a(0) { }
+};
+
+A a;