When in C++, make EnumConstant names hide tag names in the same scope, instead of colliding with them.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@53702 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaDecl.cpp

@@ -2121,7 +2121,12 @@ Sema::DeclTy *Sema::ActOnEnumConstant(Scope *S, DeclTy *theEnumDecl,
   // Verify that there isn't already something declared with this name in this
   // scope.
   if (Decl *PrevDecl = LookupDecl(Id, Decl::IDNS_Ordinary, S)) {
-    if (IdResolver.isDeclInScope(PrevDecl, CurContext, S)) {
+    // When in C++, we may get a TagDecl with the same name; in this case the
+    // enum constant will 'hide' the tag.
+    assert((getLangOptions().CPlusPlus || !isa<TagDecl>(PrevDecl)) &&
+           "Received TagDecl when not in C++!");
+    if (!isa<TagDecl>(PrevDecl) &&
+        IdResolver.isDeclInScope(PrevDecl, CurContext, S)) {
       if (isa<EnumConstantDecl>(PrevDecl))
         Diag(IdLoc, diag::err_redefinition_of_enumerator, Id->getName());
       else

test/Sema/class-names.cpp

@@ -48,3 +48,5 @@ void bar3() {
 }
 
 enum E e2;
+
+enum E2 { E2 };