[Clang] define __cpp_named_character_escapes

Define the feature test macro for named character escapes.
I assume this was not done because it was implemented before formally accepted, right? cxx_status says the paper is implemented.

Reviewed By: cor3ntin

Differential Revision: https://reviews.llvm.org/D134898

1 files changed, 3 insertions, 2 deletions

diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index 04ebeea..e9bfab9 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -697,10 +697,11 @@ static void InitializeCPlusPlusFeatureTestMacros(const LangOptions &LangOpts,
     Builder.defineMacro("__cpp_multidimensional_subscript", "202110L");
   }
 
-  // We provide this as an extension in earlier language modes, so we
-  // also define the macro.
+  // We provide those C++2b features as extensions in earlier language modes, so
+  // we also define their feature test macros.
   if (LangOpts.CPlusPlus11)
     Builder.defineMacro("__cpp_static_call_operator", "202207L");
+  Builder.defineMacro("__cpp_named_character_escapes", "202207L");
 
   if (LangOpts.Char8)
     Builder.defineMacro("__cpp_char8_t", "201811L");