`inspect.getfile` doesn't properly handle PEP 420

[TheTechRobo]

Bug report

inspect.getfile handles all __file__ is None modules as built-in. Cf.

cpython/Lib/inspect.py

Lines 898 to 901 in f298ba1

	if ismodule(object):
	if getattr(object, '__file__', None):
	return object.__file__
	raise TypeError('{!r} is a built-in module'.format(object))

This leads to PEP 420 packages being treated as built-in, as implicit namespaces have file set to None, but __path__ set to the actual path.

Creating PEP 420 directory:

~ ❯❯❯ mkdir python_test
~ ❯❯❯ vim python_test/hello.py

Python interpreter

Python 3.9.7 (default, Oct 10 2021, 14:08:54)
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import python_test
>>> import inspect
>>> inspect.getfile(python_test)
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "/opt/python-3.9.7/lib/python3.9/inspect.py", line 660, in getfile
 raise TypeError('{!r} is a built-in module'.format(object))
TypeError: <module 'python_test' (namespace)> is a built-in module
>>> print(python_test.__file__)
None
>>> print(python_test.__path__)
_NamespacePath(['/home/thetechrobo/python_test'])

Your environment

• CPython versions tested on: 3.9.7
• Operating system and architecture: Elive Linux 3.8.27 64-bit (Debian Bullseye); custom Python installation

Apologies if this is a duplicate. I've searched for any related issues, but I may have missed one.

Linked PRs

• gh-92525: make inspect.getfile PEP 420 compliant #92635

[serhiy-storchaka]

What are you going to do with the result? You cannot open a file, and inspect.getsource() will still fail.

[TheTechRobo]

@serhiy-storchaka I tried to use it for debugging, trying to figure out where the package was being imported from. The error message is currently wrong so it is a pretty annoying issue.