[clang] Bumps __cplusplus version.

[Mordante]

Summary

This is the version as published in Nxxx.

[Mordante]

This is already done in a different patch.

clang/lib/Frontend/InitPreprocessor.cpp

if (!LangOpts.CPlusPlus) {
     else if (LangOpts.C11)
       Builder.defineMacro("__STDC_VERSION__", "201112L");
     else if (LangOpts.C99)
       Builder.defineMacro("__STDC_VERSION__", "199901L");
     else if (!LangOpts.GNUMode && LangOpts.Digraphs)
       Builder.defineMacro("__STDC_VERSION__", "199409L");
   } else {
     //   -- __cplusplus
-    // FIXME: Use correct value for C++23.
-    if (LangOpts.CPlusPlus2b)
-      Builder.defineMacro("__cplusplus", "202101L");
+    if (LangOpts.CPlusPlus23)
+      Builder.defineMacro("__cplusplus", "202302L");
     //      [C++20] The integer literal 202002L.
     else if (LangOpts.CPlusPlus20)
       Builder.defineMacro("__cplusplus", "202002L");
     //      [C++17] The integer literal 201703L.
     else if (LangOpts.CPlusPlus17)
       Builder.defineMacro("__cplusplus", "201703L");
     //      [C++14] The name __cplusplus is defined to the value 201402L when
     //      compiling a C++ translation unit.

clang/test/OpenMP/target_update_messages.cpp

 template <typename T, int I>
 struct bar {
   void func() {
     #pragma omp target map(to: a) // expected-error {{incomplete type 'FOO' where a complete type is required}}
     foo();
   }
 };
 
-#if defined(__cplusplus) && __cplusplus >= 202101L
+#if defined(__cplusplus) && __cplusplus >= 202302L
 
 namespace cxx2b {
 
 struct S {
   int operator[](auto...);
 };
 
 void f() {

clang/test/Preprocessor/init.c

 //
 //
 // RUN: %clang_cc1 -x c++ -fgnuc-version=4.2.1 -std=c++2b -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix CXX2B %s
 //
 // CXX2B:#define __GNUG__ 4
 // CXX2B:#define __GXX_EXPERIMENTAL_CXX0X__ 1
 // CXX2B:#define __GXX_RTTI 1
 // CXX2B:#define __GXX_WEAK__ 1
-// CXX2B:#define __cplusplus 202101L
+// CXX2B:#define __cplusplus 202302L
 // CXX2B:#define __private_extern__ extern
 //
 // RUN: %clang_cc1 -x c++ -fgnuc-version=4.2.1 -std=c++20 -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix CXX2A %s
 // RUN: %clang_cc1 -x c++ -fgnuc-version=4.2.1 -std=c++2a -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix CXX2A %s
 //
 // CXX2A:#define __GNUG__ 4
 // CXX2A:#define __GXX_EXPERIMENTAL_CXX0X__ 1
 // CXX2A:#define __GXX_RTTI 1

 //
 // RUN: %clang_cc1 -ffreestanding -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix FREESTANDING %s
 // FREESTANDING:#define __STDC_HOSTED__ 0
 //
 // RUN: %clang_cc1 -x c++ -fgnuc-version=4.2.1 -std=gnu++2b -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix GXX2B %s
 //
 // GXX2B:#define __GNUG__ 4
 // GXX2B:#define __GXX_WEAK__ 1
-// GXX2B:#define __cplusplus 202101L
+// GXX2B:#define __cplusplus 202302L
 // GXX2B:#define __private_extern__ extern
 //
 // RUN: %clang_cc1 -x c++ -fgnuc-version=4.2.1 -std=gnu++20 -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix GXX2A %s
 // RUN: %clang_cc1 -x c++ -fgnuc-version=4.2.1 -std=gnu++2a -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix GXX2A %s
 //
 // GXX2A:#define __GNUG__ 4
 // GXX2A:#define __GXX_WEAK__ 1
 // GXX2A:#define __cplusplus 202002L