fix clang compiler version in _Py_COMPILER

Author: chris-eibl

Misc/NEWS.d/next/Library/2026-09-12-18-59-21.gh-issue-157368.2DirHP.rst

@@ -0,0 +1,3 @@
+Fix truncated :data:`sys.version` in case of clang-cl versions greater or
+equal 22 on Windows. Also fixes the Windows on Arm case, where the Microsoft
+compiler was reported instead of clang. Patch by Chris Eibl.

PC/pyconfig.h

@@ -148,17 +148,24 @@ WIN32 is still required for the locale module.
 #define MS_WIN64
 #endif
 
+#ifdef __clang__
+#define _Py_CLANG_COMPILER(platform) ( \
+   "[Clang " _Py_STRINGIZE(__clang_major__)"." _Py_STRINGIZE(__clang_minor__ ) \
+   "." _Py_STRINGIZE(__clang_patchlevel__) " " platform \
+   " with MSC v." _Py_STRINGIZE(_MSC_VER) " CRT]")
+#endif
+
 /* set the _Py_COMPILER and support tier
  *
  * win_amd64 MSVC (x86_64-pc-windows-msvc): 1
  * win32 MSVC (i686-pc-windows-msvc): 1
  * win_arm64 MSVC (aarch64-pc-windows-msvc): 2
- * other archs and ICC: 0
+ * other archs and clang-cl/ICC: 0
  */
 #ifdef MS_WIN64
 #if defined(_M_X64) || defined(_M_AMD64)
 #if defined(__clang__)
-#define _Py_COMPILER ("[Clang " __clang_version__ "] 64 bit (AMD64) with MSC v." _Py_STRINGIZE(_MSC_VER) " CRT]")
+#define _Py_COMPILER _Py_CLANG_COMPILER("64 bit (AMD64)")
 #define PY_SUPPORT_TIER 0
 #elif defined(__INTEL_COMPILER)
 #define _Py_COMPILER ("[ICC v." _Py_STRINGIZE(__INTEL_COMPILER) " 64 bit (amd64) with MSC v." _Py_STRINGIZE(_MSC_VER) " CRT]")
@@ -169,8 +176,13 @@ WIN32 is still required for the locale module.
 #endif /* __clang__ */
 #define PYD_PLATFORM_TAG "win_amd64"
 #elif defined(_M_ARM64)
+#if defined(__clang__)
+#define _Py_COMPILER _Py_CLANG_COMPILER("64 bit (ARM64)")
+#define PY_SUPPORT_TIER 0
+#else
 #define _Py_COMPILER _Py_PASTE_VERSION("64 bit (ARM64)")
 #define PY_SUPPORT_TIER 2
+#endif /* __clang__ */
 #define PYD_PLATFORM_TAG "win_arm64"
 #else
 #define _Py_COMPILER _Py_PASTE_VERSION("64 bit (Unknown)")
@@ -220,7 +232,7 @@ typedef _W64 int Py_ssize_t;
 #if defined(MS_WIN32) && !defined(MS_WIN64)
 #if defined(_M_IX86)
 #if defined(__clang__)
-#define _Py_COMPILER ("[Clang " __clang_version__ "] 32 bit (Intel) with MSC v." _Py_STRINGIZE(_MSC_VER) " CRT]")
+#define _Py_COMPILER _Py_CLANG_COMPILER("32 bit (Intel)")
 #define PY_SUPPORT_TIER 0
 #elif defined(__INTEL_COMPILER)
 #define _Py_COMPILER ("[ICC v." _Py_STRINGIZE(__INTEL_COMPILER) " 32 bit (Intel) with MSC v." _Py_STRINGIZE(_MSC_VER) " CRT]")