[3.12] gh-127906: Backport test_cppext changes from the main branch (#127915)

Lib/test/test_cppext/setup.py

@@ -1,8 +1,8 @@
 # gh-91321: Build a basic C++ test extension to check that the Python C API is
 # compatible with C++ and does not emit C++ compiler warnings.
 import os
+import platform
 import shlex
-import sys
 import sysconfig
 from test import support
 
@@ -10,6 +10,7 @@ from setuptools import setup, Extension
 
 
 SOURCE = 'extension.cpp'
+
 if not support.MS_WINDOWS:
     # C++ compiler flags for GCC and clang
     CPPFLAGS = [
@@ -19,34 +20,77 @@ if not support.MS_WINDOWS:
         '-Werror',
     ]
 else:
-    # Don't pass any compiler flag to MSVC
-    CPPFLAGS = []
+    # MSVC compiler flags
+    CPPFLAGS = [
+        # Display warnings level 1 to 4
+        '/W4',
+        # Treat all compiler warnings as compiler errors
+        '/WX',
+    ]
 
 
 def main():
     cppflags = list(CPPFLAGS)
-    std = os.environ["CPYTHON_TEST_CPP_STD"]
-    name = os.environ["CPYTHON_TEST_EXT_NAME"]
+    std = os.environ.get("CPYTHON_TEST_CPP_STD", "")
+    module_name = os.environ["CPYTHON_TEST_EXT_NAME"]
 
-    cppflags = [*CPPFLAGS, f'-std={std}']
+    cppflags = list(CPPFLAGS)
+    cppflags.append(f'-DMODULE_NAME={module_name}')
+
+    # Add -std=STD or /std:STD (MSVC) compiler flag
+    if std:
+        if support.MS_WINDOWS:
+            cppflags.append(f'/std:{std}')
+        else:
+            cppflags.append(f'-std={std}')
 
     # gh-105776: When "gcc -std=11" is used as the C++ compiler, -std=c11
     # option emits a C++ compiler warning. Remove "-std11" option from the
     # CC command.
     cmd = (sysconfig.get_config_var('CC') or '')
     if cmd is not None:
+        if support.MS_WINDOWS:
+            std_prefix = '/std'
+        else:
+            std_prefix = '-std'
         cmd = shlex.split(cmd)
-        cmd = [arg for arg in cmd if not arg.startswith('-std=')]
+        cmd = [arg for arg in cmd if not arg.startswith(std_prefix)]
         cmd = shlex.join(cmd)
         # CC env var overrides sysconfig CC variable in setuptools
         os.environ['CC'] = cmd
 
-    cpp_ext = Extension(
-        name,
+    # On Windows, add PCbuild\amd64\ to include and library directories
+    include_dirs = []
+    library_dirs = []
+    if support.MS_WINDOWS:
+        srcdir = sysconfig.get_config_var('srcdir')
+        machine = platform.uname().machine
+        pcbuild = os.path.join(srcdir, 'PCbuild', machine)
+        if os.path.exists(pcbuild):
+            # pyconfig.h is generated in PCbuild\amd64\
+            include_dirs.append(pcbuild)
+            # python313.lib is generated in PCbuild\amd64\
+            library_dirs.append(pcbuild)
+            print(f"Add PCbuild directory: {pcbuild}")
+
+    # Display information to help debugging
+    for env_name in ('CC', 'CFLAGS', 'CPPFLAGS'):
+        if env_name in os.environ:
+            print(f"{env_name} env var: {os.environ[env_name]!r}")
+        else:
+            print(f"{env_name} env var: <missing>")
+    print(f"extra_compile_args: {cppflags!r}")
+
+    ext = Extension(
+        module_name,
         sources=[SOURCE],
         language='c++',
-        extra_compile_args=cppflags)
-    setup(name='internal' + name, version='0.0', ext_modules=[cpp_ext])
+        extra_compile_args=cppflags,
+        include_dirs=include_dirs,
+        library_dirs=library_dirs)
+    setup(name=f'internal_{module_name}',
+          version='0.0',
+          ext_modules=[ext])
 
 
 if __name__ == "__main__":