PR20769: Fix confusion when checking whether a prior default argument was in
scope when checking for conflicts.

llvm-svn: 216628
diff --git a/clang/lib/Sema/IdentifierResolver.cpp b/clang/lib/Sema/IdentifierResolver.cpp
index 2a5bacf..6586fb3 100644
--- a/clang/lib/Sema/IdentifierResolver.cpp
+++ b/clang/lib/Sema/IdentifierResolver.cpp
@@ -130,6 +130,9 @@
     return false;
   }
 
+  // FIXME: If D is a local extern declaration, this check doesn't make sense;
+  // we should be checking its lexical context instead in that case, because
+  // that is its scope.
   DeclContext *DCtx = D->getDeclContext()->getRedeclContext();
   return AllowInlineNamespace ? Ctx->InEnclosingNamespaceSetOf(DCtx)
                               : Ctx->Equals(DCtx);