importlib.metadata entry points might load wrong module and crash

$ sip-build --help
Traceback (most recent call last):
  File "/usr/bin/sip-build", line 33, in <module>
    sys.exit(load_entry_point('sip==5.4.0', 'console_scripts', 'sip-build')())
  File "/usr/bin/sip-build", line 25, in importlib_load_entry_point
    return next(matches).load()
StopIteration

I have python-sip as well as sip5 installed on Arch Linux. In the site-packages directory:

$ ls -1d sip-*
sip-4.19.24.dist-info/
sip-5.4.0-py3.8.egg-info/

The 4.x version installs:

sipconfig.py
sipdistutils.py
sip.pyi
sip.so*

The 5.x version installs:

sipbuild/

They’re co-installable because people might need the legacy version, still.

…

It appears pkg_resources is fully capable of finding the needed distribution given version constraint on sip==5.4.0:

>>> import pkg_resources
>>> pkg_resources.load_entry_point('sip==5.4.0', 'console_scripts', 'sip-build')
<function main at 0x7f4febf588b0>
>>> pprint(pkg_resources.get_distribution('sip==5.4.0').get_entry_map())
{'console_scripts': {'sip-build': EntryPoint.parse('sip-build = sipbuild.tools.build:main'),
                     'sip-distinfo': EntryPoint.parse('sip-distinfo = sipbuild.distinfo.main:main'),
                     'sip-install': EntryPoint.parse('sip-install = sipbuild.tools.install:main'),
                     'sip-module': EntryPoint.parse('sip-module = sipbuild.module.main:main'),
                     'sip-sdist': EntryPoint.parse('sip-sdist = sipbuild.tools.sdist:main'),
                     'sip-wheel': EntryPoint.parse('sip-wheel = sipbuild.tools.wheel:main'),
                     'sip5': EntryPoint.parse('sip5 = sipbuild.legacy.sip5:main')}}

Not so with importlib.metadata, which AFAICT has no way to specify versions or indeed find multiple versions of one distribution (and is finding the old version to boot):

>>> from importlib.metadata import distribution
>>> distribution('sip').metadata['Version']
'4.19.24'
>>> distribution('sip').entry_points
[]

[miraculixx]

In my case this error occurred when installing the package in editable mode (pip install -e .), while when installed normally the entry point worked fine (pip install .)

It turns out where was a directory “<package>.egg-info” in the package’s directory, probably from a previous install. Fix was to remove this directory and run pip install -e . again.

[moan0s]

Thank you this helped me a lot! 🥳