1 files changed, 21 insertions, 3 deletions
diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index 310105a4ac6..f7c0f3f550e 100644
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -1517,16 +1517,34 @@ Parser::TryAnnotateName(bool IsAddressOfOperand,
 }
 
 bool Parser::TryKeywordIdentFallback(bool DisableKeyword) {
-  assert(Tok.isNot(tok::identifier));
+  assert(!Tok.is(tok::identifier) && !Tok.isAnnotation());
   Diag(Tok, diag::ext_keyword_as_ident)
     << PP.getSpelling(Tok)
     << DisableKeyword;
-  if (DisableKeyword)
-    Tok.getIdentifierInfo()->RevertTokenIDToIdentifier();
+  if (DisableKeyword) {
+    IdentifierInfo *II = Tok.getIdentifierInfo();
+    ContextualKeywords[II] = Tok.getKind();
+    II->RevertTokenIDToIdentifier();
+  }
   Tok.setKind(tok::identifier);
   return true;
 }
 
+bool Parser::TryIdentKeywordUpgrade() {
+  assert(Tok.is(tok::identifier));
+  const IdentifierInfo *II = Tok.getIdentifierInfo();
+  assert(II->hasRevertedTokenIDToIdentifier());
+  // If we find that this is in fact the name of a type trait,
+  // update the token kind in place and parse again to treat it as
+  // the appropriate kind of type trait.
+  llvm::SmallDenseMap<const IdentifierInfo *, tok::TokenKind>::iterator Known =
+      ContextualKeywords.find(II);
+  if (Known == ContextualKeywords.end())
+    return false;
+  Tok.setKind(Known->second);
+  return true;
+}
+
 /// TryAnnotateTypeOrScopeToken - If the current token position is on a
 /// typename (possibly qualified in C++) or a C++ scope specifier not followed
 /// by a typename, TryAnnotateTypeOrScopeToken will replace one or more tokens