1 files changed, 5 insertions, 4 deletions
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 6796f1c21bb..bdca03637db 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -1967,16 +1967,17 @@ void Preprocessor::HandleUndefDirective(Token &UndefTok) {
   // Okay, we finally have a valid identifier to undef.
   MacroInfo *MI = getMacroInfo(MacroNameTok.getIdentifierInfo());
 
+  // If the callbacks want to know, tell them about the macro #undef.
+  // Note: no matter if the macro was defined or not.
+  if (Callbacks)
+    Callbacks->MacroUndefined(MacroNameTok, MI);
+
   // If the macro is not defined, this is a noop undef, just return.
   if (MI == 0) return;
 
   if (!MI->isUsed() && MI->isWarnIfUnused())
     Diag(MI->getDefinitionLoc(), diag::pp_macro_not_used);
 
-  // If the callbacks want to know, tell them about the macro #undef.
-  if (Callbacks)
-    Callbacks->MacroUndefined(MacroNameTok, MI);
-
   if (MI->isWarnIfUnused())
     WarnUnusedMacroLocs.erase(MI->getDefinitionLoc());