gh-77532: Minor tweaks to allow compiling with PlatformToolset=ClangCL on Windows

Include/cpython/pytime.h

@@ -53,6 +53,10 @@ functions and constants
 extern "C" {
 #endif
 
+#ifdef __clang__
+struct timeval;
+#endif
+
 /* _PyTime_t: Python timestamp with subsecond precision. It can be used to
    store a duration, and so indirectly a date (related to another date, like
    UNIX epoch). */

Include/internal/pycore_tracemalloc.h

@@ -36,11 +36,13 @@ struct _PyTraceMalloc_Config {
 
 /* Pack the frame_t structure to reduce the memory footprint on 64-bit
    architectures: 12 bytes instead of 16. */
+#if defined(_MSC_VER)
+#pragma pack(push, 4)
+#endif
+
 struct
 #ifdef __GNUC__
 __attribute__((packed))
-#elif defined(_MSC_VER)
-#pragma pack(push, 4)
 #endif
 tracemalloc_frame {
     /* filename cannot be NULL: "<unknown>" is used if the Python frame

Misc/NEWS.d/next/Build/2023-01-26-19-02-11.gh-issue-77532.cXD8bg.rst

@@ -0,0 +1 @@
+Minor fixes to allow building with ``PlatformToolset=ClangCL`` on Windows.

Modules/_decimal/libmpdec/mpdecimal.c

@@ -76,6 +76,12 @@
   #endif
 #endif
 
+/* ClangCL claims to support 128-bit int, but doesn't */
+#if defined(__SIZEOF_INT128__) && defined(__clang__) && defined(_MSC_VER)
+#undef __SIZEOF_INT128__
+#endif
+
+
 
 #define MPD_NEWTONDIV_CUTOFF 1024L
 

PC/launcher2.c

@@ -465,10 +465,14 @@ dumpSearchInfo(SearchInfo *search)
         return;
     }
 
-#define DEBUGNAME(s) L"SearchInfo." ## s
-#define DEBUG(s) debug(DEBUGNAME(#s) L": %s\n", (search->s) ? (search->s) : L"(null)")
-#define DEBUG_2(s, sl) _debugStringAndLength((search->s), (search->sl), DEBUGNAME(#s))
-#define DEBUG_BOOL(s) debug(DEBUGNAME(#s) L": %s\n", (search->s) ? L"True" : L"False")
+#ifdef __clang__
+#define DEBUGNAME(s) L # s
+#else
+#define DEBUGNAME(s) # s
+#endif
+#define DEBUG(s) debug(L"SearchInfo." DEBUGNAME(s) L": %s\n", (search->s) ? (search->s) : L"(null)")
+#define DEBUG_2(s, sl) _debugStringAndLength((search->s), (search->sl), L"SearchInfo." DEBUGNAME(s))
+#define DEBUG_BOOL(s) debug(L"SearchInfo." DEBUGNAME(s) L": %s\n", (search->s) ? L"True" : L"False")
     DEBUG(originalCmdLine);
     DEBUG(restOfCmdLine);
     DEBUG(executablePath);

PC/pyconfig.h

@@ -76,30 +76,26 @@ WIN32 is still required for the locale module.
 /* Compiler specific defines */
 
 /* ------------------------------------------------------------------------*/
-/* Microsoft C defines _MSC_VER */
+/* Microsoft C defines _MSC_VER, as does clang-cl.exe */
 #ifdef _MSC_VER
 
 /* We want COMPILER to expand to a string containing _MSC_VER's *value*.
  * This is horridly tricky, because the stringization operator only works
  * on macro arguments, and doesn't evaluate macros passed *as* arguments.
- * Attempts simpler than the following appear doomed to produce "_MSC_VER"
- * literally in the string.
  */
 #define _Py_PASTE_VERSION(SUFFIX) \
         ("[MSC v." _Py_STRINGIZE(_MSC_VER) " " SUFFIX "]")
 /* e.g., this produces, after compile-time string catenation,
- *      ("[MSC v.1200 32 bit (Intel)]")
+ *      ("[MSC v.1900 64 bit (Intel)]")
  *
  * _Py_STRINGIZE(_MSC_VER) expands to
- * _Py_STRINGIZE1((_MSC_VER)) expands to
- * _Py_STRINGIZE2(_MSC_VER) but as this call is the result of token-pasting
- *      it's scanned again for macros and so further expands to (under MSVC 6)
- * _Py_STRINGIZE2(1200) which then expands to
- * "1200"
+ * _Py_STRINGIZE1(_MSC_VER) and this second macro call is scanned
+ *      again for macros and so further expands to
+ * _Py_STRINGIZE1(1900) which then expands to
+ * "1900"
  */
-#define _Py_STRINGIZE(X) _Py_STRINGIZE1((X))
-#define _Py_STRINGIZE1(X) _Py_STRINGIZE2 ## X
-#define _Py_STRINGIZE2(X) #X
+#define _Py_STRINGIZE(X) _Py_STRINGIZE1(X)
+#define _Py_STRINGIZE1(X) #X
 
 /* MSVC defines _WINxx to differentiate the windows platform types
 
@@ -122,13 +118,16 @@ WIN32 is still required for the locale module.
  */
 #ifdef MS_WIN64
 #if defined(_M_X64) || defined(_M_AMD64)
-#if defined(__INTEL_COMPILER)
+#if defined(__clang__)
+#define COMPILER ("[Clang " __clang_version__ "] 64 bit (AMD64) with MSC v." _Py_STRINGIZE(_MSC_VER) " CRT]")
+#define PY_SUPPORT_TIER 0
+#elif defined(__INTEL_COMPILER)
 #define COMPILER ("[ICC v." _Py_STRINGIZE(__INTEL_COMPILER) " 64 bit (amd64) with MSC v." _Py_STRINGIZE(_MSC_VER) " CRT]")
 #define PY_SUPPORT_TIER 0
 #else
 #define COMPILER _Py_PASTE_VERSION("64 bit (AMD64)")
 #define PY_SUPPORT_TIER 1
-#endif /* __INTEL_COMPILER */
+#endif /* __clang__ */
 #define PYD_PLATFORM_TAG "win_amd64"
 #elif defined(_M_ARM64)
 #define COMPILER _Py_PASTE_VERSION("64 bit (ARM64)")
@@ -181,13 +180,16 @@ typedef _W64 int Py_ssize_t;
 
 #if defined(MS_WIN32) && !defined(MS_WIN64)
 #if defined(_M_IX86)
-#if defined(__INTEL_COMPILER)
+#if defined(__clang__)
+#define COMPILER ("[Clang " __clang_version__ "] 32 bit (Intel) with MSC v." _Py_STRINGIZE(_MSC_VER) " CRT]")
+#define PY_SUPPORT_TIER 0
+#elif defined(__INTEL_COMPILER)
 #define COMPILER ("[ICC v." _Py_STRINGIZE(__INTEL_COMPILER) " 32 bit (Intel) with MSC v." _Py_STRINGIZE(_MSC_VER) " CRT]")
 #define PY_SUPPORT_TIER 0
 #else
 #define COMPILER _Py_PASTE_VERSION("32 bit (Intel)")
 #define PY_SUPPORT_TIER 1
-#endif /* __INTEL_COMPILER */
+#endif /* __clang__ */
 #define PYD_PLATFORM_TAG "win32"
 #elif defined(_M_ARM)
 #define COMPILER _Py_PASTE_VERSION("32 bit (ARM)")

PCbuild/pyproject.props

@@ -25,7 +25,8 @@
     <_DebugPreprocessorDefinition>NDEBUG;</_DebugPreprocessorDefinition>
     <_DebugPreprocessorDefinition Condition="$(Configuration) == 'Debug'">_DEBUG;</_DebugPreprocessorDefinition>
     <_PlatformPreprocessorDefinition>_WIN32;</_PlatformPreprocessorDefinition>
-    <_PlatformPreprocessorDefinition Condition="$(Platform) == 'x64'">_WIN64;_M_X64;</_PlatformPreprocessorDefinition>
+    <_PlatformPreprocessorDefinition Condition="$(Platform) == 'x64'">_WIN64;</_PlatformPreprocessorDefinition>
+    <_PlatformPreprocessorDefinition Condition="$(Platform) == 'x64' and $(PlatformToolset) != 'ClangCL'">_M_X64;$(_PlatformPreprocessorDefinition)</_PlatformPreprocessorDefinition>
     <_Py3NamePreprocessorDefinition>PY3_DLLNAME=L"$(Py3DllName)";</_Py3NamePreprocessorDefinition>
   </PropertyGroup>
   <ItemDefinitionGroup>
@@ -45,8 +46,10 @@
       <SuppressStartupBanner>true</SuppressStartupBanner>
       <WholeProgramOptimization>true</WholeProgramOptimization>
       <ControlFlowGuard Condition="$(EnableControlFlowGuard) != ''">$(EnableControlFlowGuard)</ControlFlowGuard>
-      <AdditionalOptions>/utf-8 %(AdditionalOptions)</AdditionalOptions>
       <MultiProcessorCompilation>true</MultiProcessorCompilation>
+      <AdditionalOptions>/utf-8 %(AdditionalOptions)</AdditionalOptions>
+      <AdditionalOptions Condition="$(PlatformToolset) == 'ClangCL'">-Wno-deprecated-non-prototype -Wno-unused-label -Wno-pointer-sign -Wno-incompatible-pointer-types-discards-qualifiers -Wno-unused-function %(AdditionalOptions)</AdditionalOptions>
+      <AdditionalOptions Condition="$(Configuration) != 'Debug' and $(PlatformToolset) == 'ClangCL'">-flto %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
     <ClCompile Condition="$(Configuration) == 'Debug'">
       <InlineFunctionExpansion>OnlyExplicitInline</InlineFunctionExpansion>