1 files changed, 2 insertions, 0 deletions
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index ccbfea6..81f1c71 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -4265,6 +4265,8 @@ void Parser::ParseDeclarationSpecifiers(
 
     // constexpr, consteval, constinit specifiers
     case tok::kw_constexpr:
+      if (getLangOpts().C23)
+        Diag(Tok, diag::warn_c23_compat_keyword) << Tok.getName();
       isInvalid = DS.SetConstexprSpec(ConstexprSpecKind::Constexpr, Loc,
                                       PrevSpec, DiagID);
       break;