Stdlib packages import local packages from working dir instead of other stdlib packages

[krfricke]

Bug report

Global packages (e.g. enum) try to import from local packages in the current working dir, even if a same-named stdlib package exists.

For instance, if a types.py exists in the local directory, import enum will fail:

> touch types.py
> python
Python 3.10.9 (main, Jan 20 2023, 17:02:49) [Clang 13.0.0 (clang-1300.0.27.3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import enum
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/kai/.pyenv/versions/3.10.9/lib/python3.10/enum.py", line 2, in <module>
    from types import MappingProxyType, DynamicClassAttribute
ImportError: cannot import name 'MappingProxyType' from 'types' (/home/kai/sandbox/types.py)

The correct package to import should be the stdlib types.py package, not the local types.py.

Your environment

• CPython versions tested on: Python 3.10.4, 3.10.9, 3.8.6
• Bug does not come up in 3.8.7
• Operating system and architecture: Mac x86_64

[hauntsaninja]

Duplicate of #95893, #90482, #42852, #73790, #66368, #65577, #65401, etc

See https://ncoghlan-devs-python-notes.readthedocs.io/en/latest/python_concepts/import_traps.html#the-name-shadowing-trap

[eryksun]

When running interactively, an empty string is prepended to sys.path. This gets evaluated to whatever the current working directory is at the time of each import. When running a script, the directory of the script gets prepended to sys.path. Usually the script directory is not the same as the current working directory.

You can run in isolated mode (i.e. -I command-line option) to avoid prepending either the working directory or the script directory. However, this is an extreme measure that also disables reading PYTHON* environment variables and the user site packages. Starting with Python 3.11, there's a -P command-line option to get a safe sys.path that doesn't prepend these directories.

[krfricke]

Thanks for the explanation and sorry for the duplicate (I tried searching but didn't find the other issues).

Looking forward to the -P option - for our case we found another workaround.

Thanks!