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Fixed build_ext assumption that cross-compilation on Windows always uses MSVCCompiler#399

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jaraco merged 2 commits into
pypa:mainfrom
Avasam:patch-1
Jul 7, 2026
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Fixed build_ext assumption that cross-compilation on Windows always uses MSVCCompiler#399
jaraco merged 2 commits into
pypa:mainfrom
Avasam:patch-1

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@Avasam

@Avasam Avasam commented Feb 20, 2026 •
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Fixes the following error if providing --plat-name when using msys2-mingw on Windows:

Traceback (most recent call last):
  File "D:/a/_temp/msys64/mingw64/lib/python3.12/site-packages/pyproject_hooks/_in_process/_in_process.py", line 389, in <module>
    main()
  File "D:/a/_temp/msys64/mingw64/lib/python3.12/site-packages/pyproject_hooks/_in_process/_in_process.py", line 373, in main
    json_out["return_val"] = hook(**hook_input["kwargs"])
                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:/a/_temp/msys64/mingw64/lib/python3.12/site-packages/pyproject_hooks/_in_process/_in_process.py", line 280, in build_wheel
    return _build_backend().build_wheel(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/build_meta.py", line 438, in build_wheel
    return _build(['bdist_wheel'])
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/build_meta.py", line 429, in _build
    return self._build_with_temp_dir(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/build_meta.py", line 410, in _build_with_temp_dir
    self.run_setup()
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/build_meta.py", line 317, in run_setup
    exec(code, locals())
  File "<string>", line 1963, in <module>
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/__init__.py", line 117, in setup
    return distutils.core.setup(**attrs)  # type: ignore[return-value]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/_distutils/core.py", line 186, in setup
    return run_commands(dist)
           ^^^^^^^^^^^^^^^^^^
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/_distutils/core.py", line 202, in run_commands
    dist.run_commands()
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/_distutils/dist.py", line 1000, in run_commands
    self.run_command(cmd)
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/dist.py", line 1107, in run_command
    super().run_command(command)
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/_distutils/dist.py", line 1019, in run_command
    cmd_obj.run()
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/command/bdist_wheel.py", line 370, in run
    self.run_command("build")
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/_distutils/cmd.py", line 341, in run_command
    self.distribution.run_command(command)
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/dist.py", line 1107, in run_command
    super().run_command(command)
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/_distutils/dist.py", line 1019, in run_command
    cmd_obj.run()
  File "<string>", line 354, in run
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/_distutils/command/build.py", line 135, in run
    self.run_command(cmd_name)
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/_distutils/cmd.py", line 341, in run_command
    self.distribution.run_command(command)
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/dist.py", line 1107, in run_command
    super().run_command(command)
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/_distutils/dist.py", line 1019, in run_command
    cmd_obj.run()
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/command/build_ext.py", line 97, in run
    _build_ext.run(self)
  File "D:/a/_temp/msys64/tmp/build-env-g6pjoax9/lib/python3.12/site-packages/setuptools/_distutils/command/build_ext.py", line 336, in run
    self.compiler.initialize(self.plat_name)
    ^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'MinGW32Compiler' object has no attribute 'initialize'

This could've been caught with static type checking, but attr-defined is currently disabled in mypy

@Avasam Avasam mentioned this pull request Feb 20, 2026
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Avasam
Avasam commented Feb 26, 2026
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Comment thread distutils/command/build_ext.py Outdated
@Avasam Avasam mentioned this pull request May 1, 2026
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@jaraco jaraco mentioned this pull request Jul 5, 2026
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@jaraco @claude
Provide a degenerate Compiler.initialize() so cross-compiling works f…
85fc968 
…or non-MSVC compilers

build_ext.run() unconditionally called compiler.initialize() when
cross-compiling on Windows, assuming an MSVCCompiler. With any other
compiler (e.g. MinGW/msys2) this raised AttributeError.

Rather than guard the call with hasattr(), give the base Compiler a no-op
initialize() that non-MSVC compilers inherit; MSVCCompiler continues to
override it. This also makes the method visible to static type checkers.
The redundant os.name == 'nt' guard is dropped since initialize() is now
safe on every compiler.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
@jaraco jaraco merged commit 8f341ca into pypa:main Jul 7, 2026
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@Avasam Avasam deleted the patch-1 branch July 7, 2026 19:54
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@Avasam @jaraco