importlib.import_module() doesn't raise ModuleNotFoundError for non-existent modules in Python 3.11.4+.

[felixxm]

Checklist

• I am confident this is a bug in CPython, not a bug in a third-party project
• I have searched the CPython issue tracker,
  and am confident this bug has not been reported before

CPython versions tested on:

3.11

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

Python 3.11.4 (main, Jul 19 2023, 08:05:31) [GCC 11.3.0]

A clear and concise description of the bug:

# Python 3.11.4
# importlib.import_module() doesn't raise ModuleNotFoundError for non-existent modules.
>>> from importlib import import_module
>>> import_module("django.contrib.contenttypes.templatetags")
<module 'django.contrib.contenttypes.templatetags' from '/django/django/templatetags/__init__.py'>

# Python 3.10.9
>>> from importlib import import_module
>>> import_module("django.contrib.contenttypes.templatetags")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.10/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1004, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'django.contrib.contenttypes.templatetags'

[Eclips4]

Hello!
I don't see any non-existent modules in the first example.
You try to import django module (or package, it doesn't matter) and its imported. Maybe you have installed django in your virtual environment?

Please, explain why do you think this is a bug.

[felixxm]

Please, explain why do you think this is a bug.

templatetags module doesn't exist in django.contrib.contenttypes.

[felixxm]

Many of our tests stopped working after bumping to Python 3.11.4, check out CI logs.

[Eclips4]

Please, explain why do you think this is a bug.

templatetags module doesn't exist in django.contrib.contenttypes.

Interesting. I cannot reproduce it local. I've tried it on python 3.11.4 and django 4.2.4:

Python 3.11.4 (main, Jul 25 2023, 17:36:13) [Clang 14.0.3 (clang-1403.0.22.14.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from importlib import import_module
>>> import_module("django.contrib.contenttypes.templatetags")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/homebrew/Cellar/python@3.11/3.11.4_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1140, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'django.contrib.contenttypes.templatetags'

Did I miss something?

[felixxm]

Did I miss something?

🤔 Maybe it's an issue in "editable" mode: pip install -e <django_main_directory>.

[Eclips4]

Did I miss something?

🤔 Maybe it's an issue in "editable" mode: pip install -e <django_main_directory>.

Oh, you're right. With editable mode I can reproduce it:

Python 3.11.4 (main, Jul 25 2023, 17:36:13) [Clang 14.0.3 (clang-1403.0.22.14.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from importlib import import_module
>>> import_module("django.contrib.contenttypes.templatetags")
<module 'django.contrib.contenttypes.templatetags' from '/Users/admin/PycharmProjects/django/django/templatetags/__init__.py'>
>>> 

[Eclips4]

I'm not expert in this area, but it's looks like a problem with pip editable mode.

[wd0517]

not only 3.11.4, but 3.10.12 and 3.8.10 on my machine also have this strange behavior with editable mode, However I remember it working last week.

[felixxm]

I checked and 3.11.3 is also affected (we've bumped 3.11.1 to 3.11.4 on our CI). I will try to bisect this regression.

[erlend-aasland]

Thanks, @felixxm

[felixxm]

I'm extremely puzzled 🕵️ . Yesterday I was able to reproduce this issue on different Python versions (build from source, build directly from branches, packed, etc.) on new and existing virtual environments. Today everything works fine 🤯