[BUG] When running bdist_wheel on Windows, warning appears: "Config variable 'Py_DEBUG' is unset, Python ABI tag may be incorrect"

[JoevDubach]

setuptools version

setuptools==74.1.2

Python version

Python 3.9.13

OS

Windows

Additional environment information

No response

Description

Now that setuptools has incorporated bdist_wheel.py as setuptools/command/bdist_wheel.py, the issue pypa/wheel#461 that was previously fixable by changing wheel is now fixable by changing setuptools, so I'm reporting it in updated form here.

When building a wheel with "python -m build --wheel" on Windows, it ends up executing wheel/bdist_wheel.py, and outputs this warning to screen:

  if get_flag("Py_DEBUG", hasattr(sys, "gettotalrefcount"), warn=(impl == "cp")):

This is because setuptools/command/bdist_wheel.py has a local implementation of get_abi_tag() that's called by bdist_wheel.get_tag(), which is called by bdist_wheel.run(), bdist_wheel.write_wheelfile(), and editable_wheel._create_wheel_file(). This local implementation isn't able to detect the debug attribute properly on Windows, so it issues a warning.

But setuptools/_vendor/packaging/tags.py has another implementation of this functionality in _cpython_abis() that detects the debug attribute more correctly:

    py_version = tuple(py_version)  # To allow for version comparison.
    abis = []
    version = _version_nodot(py_version[:2])
    threading = debug = pymalloc = ucs4 = ""
    with_debug = _get_config_var("Py_DEBUG", warn)
    has_refcount = hasattr(sys, "gettotalrefcount")
    # Windows doesn't set Py_DEBUG, so checking for support of debug-compiled
    # extension modules is the best option.
    # https://github.com/pypa/pip/issues/3383#issuecomment-173267692
    has_ext = "_d.pyd" in EXTENSION_SUFFIXES
    if with_debug or (with_debug is None and (has_refcount or has_ext)):
        debug = "d"
    if py_version >= (3, 13) and _get_config_var("Py_GIL_DISABLED", warn):
        threading = "t"
    if py_version < (3, 8):
        with_pymalloc = _get_config_var("WITH_PYMALLOC", warn)
        if with_pymalloc or with_pymalloc is None:
            pymalloc = "m"
        if py_version < (3, 3):
            unicode_size = _get_config_var("Py_UNICODE_SIZE", warn)
            if unicode_size == 4 or (
                unicode_size is None and sys.maxunicode == 0x10FFFF
            ):
                ucs4 = "u"
    elif debug:
        # Debug builds can also load "normal" extension modules.
        # We can also assume no UCS-4 or pymalloc requirement.
        abis.append(f"cp{version}{threading}")
    abis.insert(0, f"cp{version}{threading}{debug}{pymalloc}{ucs4}")
    return abis

tags._cpython_abis() is called by tags.cpython_tags(), which is called by tags.sys_tags(). See pypa/packaging#194 and pypa/packaging#172 for work that improved this debug attribute detection on Windows.

setuptools/command/bdist_wheel.py already has:

from packaging import tags, version as _packaging_version

...and uses tags.interpreter_name(), tags.interpreter_version(), and tags.sys_tags(). So it seems like using the tags module a little more extensively should be safe, as long as it gives the same behavior on all Python versions still supported by setuptools (>=3.8).

It seems to me that the local implementation of get_abi_tag() could be replaced with an appropriate call to tags.sys_tags(), and get_abi_tag() could be removed. The current code does:

            impl_ver = tags.interpreter_version()
            impl = impl_name + impl_ver
            # We don't work on CPython 3.1, 3.0.
            if self.py_limited_api and (impl_name + impl_ver).startswith("cp3"):
                impl = self.py_limited_api
                abi_tag = "abi3"
            else:
                abi_tag = str(get_abi_tag()).lower()
            tag = (impl, abi_tag, plat_name)
            # issue gh-374: allow overriding plat_name
            supported_tags = [
                (t.interpreter, t.abi, plat_name) for t in tags.sys_tags()
            ]
            assert (
                tag in supported_tags
            ), f"would build wheel with unsupported tag {tag}"

...where I could imagine it instead doing:

            impl_ver = tags.interpreter_version()
            impl = impl_name + impl_ver
            # issue gh-374: allow overriding plat_name
            supported_tags = [
                (t.interpreter, t.abi, plat_name) for t in tags.sys_tags()
            ]
            # We don't work on CPython 3.1, 3.0.
            if self.py_limited_api and (impl_name + impl_ver).startswith("cp3"):
                impl = self.py_limited_api
                abi_tag = "abi3"
                tag = (impl, abi_tag, plat_name)
                assert (
                    tag in supported_tags
                ), f"would build wheel with unsupported tag {tag}"
            else:
                tag = supported_tags[0]

This change works for my use case and avoids the warning.

If this isn't feasible for some reason, another option would be to change the local implementation of get_abi_tag() to imitate the relevant packaging.tags._cpython_abis() code that detects the debug and with_pymalloc attributes, with a particular care not to warn on Windows in an expected situation that is immediately going to be rectified by an appropriate alternate detection mechanism. This is more complicated, so I won't attempt to suggest the exact patch for this option.

Expected behavior

Not getting this warning being output to screen:

  if get_flag("Py_DEBUG", hasattr(sys, "gettotalrefcount"), warn=(impl == "cp")):

How to Reproduce

1. Run commands:
   mkdir setuptoolsbug
   mkdir setuptoolsbug\mymod
   cd setuptoolsbug\mymod

2. Create setuptoolsbug\mymod\setup.py:

## forces the wheelname to include the binary component
class BinaryDistribution(setuptools.dist.Distribution):
    def has_ext_modules(self):
        return True

setuptools.setup(
    name = 'mymod',
    version = "1.0.0.0",
    description = 'MyMod',
    packages = setuptools.find_packages(),
    include_package_data=True,
    python_requires='>=3.9',
    distclass = BinaryDistribution
)

3. Run commands:

..\myenv\Scripts\python -m pip install --disable-pip-version-check setuptools==74.1.2
..\myenv\Scripts\python -m pip install --disable-pip-version-check build==1.2.2
mkdir ..\wheelhouse
..\myenv\Scripts\python -m build --no-isolation --skip-dependency-check --wheel --outdir ..\wheelhouse

Output

D:\work\setuptoolsbug\mymod>..\myenv\Scripts\python -m pip install --disable-pip-version-check setuptools==74.1.2
Collecting setuptools==74.1.2
  Using cached setuptools-74.1.2-py3-none-any.whl (1.3 MB)
Installing collected packages: setuptools
  Attempting uninstall: setuptools
    Found existing installation: setuptools 58.1.0
    Uninstalling setuptools-58.1.0:
      Successfully uninstalled setuptools-58.1.0
Successfully installed setuptools-74.1.2

D:\work\setuptoolsbug\mymod>..\myenv\Scripts\python -m pip install --disable-pip-version-check build==1.2.2
Collecting build==1.2.2
  Using cached build-1.2.2-py3-none-any.whl (22 kB)
Collecting tomli>=1.1.0
  Using cached tomli-2.0.1-py3-none-any.whl (12 kB)
Collecting packaging>=19.1
  Using cached packaging-24.1-py3-none-any.whl (53 kB)
Collecting colorama
  Using cached colorama-0.4.6-py2.py3-none-any.whl (25 kB)
Collecting pyproject_hooks
  Using cached pyproject_hooks-1.1.0-py3-none-any.whl (9.2 kB)
Collecting importlib-metadata>=4.6
  Using cached importlib_metadata-8.4.0-py3-none-any.whl (26 kB)
Collecting zipp>=0.5
  Using cached zipp-3.20.1-py3-none-any.whl (9.0 kB)
Installing collected packages: zipp, tomli, pyproject_hooks, packaging, colorama, importlib-metadata, build
Successfully installed build-1.2.2 colorama-0.4.6 importlib-metadata-8.4.0 packaging-24.1 pyproject_hooks-1.1.0 tomli-2.0.1 zipp-3.20.1

D:\work\setuptoolsbug\mymod>mkdir ..\wheelhouse

D:\work\setuptoolsbug\mymod>..\myenv\Scripts\python -m build --no-isolation --skip-dependency-check --wheel --outdir ..\wheelhouse
* Building wheel...
running bdist_wheel
running build
running build_ext
installing to build\bdist.win-amd64\wheel
running install
running install_lib
warning: install_lib: 'build\lib.win-amd64-cpython-39' does not exist -- no Python modules to install

running install_egg_info
running egg_info
writing mymod.egg-info\PKG-INFO
writing dependency_links to mymod.egg-info\dependency_links.txt
writing top-level names to mymod.egg-info\top_level.txt
reading manifest file 'mymod.egg-info\SOURCES.txt'
writing manifest file 'mymod.egg-info\SOURCES.txt'
Copying mymod.egg-info to build\bdist.win-amd64\wheel\.\mymod-1.0.0.0-py3.9.egg-info
running install_scripts
D:\work\setuptoolsbug\myenv\lib\site-packages\setuptools\command\bdist_wheel.py:114: RuntimeWarning: Config variable 'Py_DEBUG' is unset, Python ABI tag may be incorrect
  if get_flag("Py_DEBUG", hasattr(sys, "gettotalrefcount"), warn=(impl == "cp")):
creating build\bdist.win-amd64\wheel\mymod-1.0.0.0.dist-info\WHEEL
creating 'D:\work\setuptoolsbug\wheelhouse\.tmp-o7l2a5kc\mymod-1.0.0.0-cp39-cp39-win_amd64.whl' and adding 'build\bdist.win-amd64\wheel' to it
adding 'mymod-1.0.0.0.dist-info/METADATA'
adding 'mymod-1.0.0.0.dist-info/WHEEL'
adding 'mymod-1.0.0.0.dist-info/top_level.txt'
adding 'mymod-1.0.0.0.dist-info/RECORD'
removing build\bdist.win-amd64\wheel
Successfully built mymod-1.0.0.0-cp39-cp39-win_amd64.whl