[clang] guard __STDC_NO_THREADS__ defination for MSVCVersion 2022 17.9 and above

Author: dipeshs809

clang/include/clang/Basic/LangOptions.h

@@ -144,6 +144,7 @@ class LangOptionsBase {
     MSVC2019_5 = 1925,
     MSVC2019_8 = 1928,
     MSVC2022_3 = 1933,
+    MSVC2022_9 = 1939,
   };
 
   enum SYCLMajorVersion {

clang/lib/Basic/Targets/OSTargets.cpp

@@ -259,8 +259,19 @@ static void addVisualCDefines(const LangOptions &Opts, MacroBuilder &Builder) {
     Builder.defineMacro("_KERNEL_MODE");
 
   Builder.defineMacro("_INTEGRAL_MAX_BITS", "64");
-  Builder.defineMacro("__STDC_NO_THREADS__");
-
+  // Define __STDC_NO_THREADS__ based on MSVC version, threads.h availability,
+  // and language standard.
+  if (!Opts.isCompatibleWithMSVC(LangOptions::MSVC2022_9)) {
+    Builder.defineMacro("__STDC_NO_THREADS__");
+  } else {
+#if defined(__has_include) && !__has_include(<threads.h>)
+    Builder.defineMacro("__STDC_NO_THREADS__");
+#endif
+#if defined(__STDC_VERSION__) && __STDC_VERSION__ < 201112L
+    Builder.defineMacro("__STDC_NO_THREADS__");
+#endif
+  }
+  // Builder.defineMacro("__STDC_NO_THREADS__");
   // Starting with VS 2022 17.1, MSVC predefines the below macro to inform
   // users of the execution character set defined at compile time.
   // The value given is the Windows Code Page Identifier: