[modules] If we reach a definition of a class for which we already have a

non-visible definition, skip the new definition and make the old one visible
instead of trying to parse it again and failing horribly. C++'s ODR allows
us to assume that the two definitions are identical.

llvm-svn: 233250

clang/lib/Sema/SemaCXXScopeSpec.cpp

@@ -218,6 +218,7 @@ bool Sema::RequireCompleteDeclContext(CXXScopeSpec &SS,
   // Fixed enum types are complete, but they aren't valid as scopes
   // until we see a definition, so awkwardly pull out this special
   // case.
+  // FIXME: The definition might not be visible; complain if it is not.
   const EnumType *enumType = dyn_cast_or_null<EnumType>(tagType);
   if (!enumType || enumType->getDecl()->isCompleteDefinition())
     return false;