mypy gets confused between non-re-exported import and a submodule of the same name
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Description
Bug Report
This is happening in opencv, relevant issue: https://github.com/opencv/opencv-python/issues/901
Type stub cv2 imports typing
Module cv2.typing also exists
The following raises a mypy error, as expected
import cv2
_ = cv2.typing.MatLike # Module "cv2" does not explicitly export attribute "typing" Mypy [attr-defined]
(note that this will work at runtime, by that's because cv2 doesn't actually import typing at runtime AND does dynamic imports to expose all its submodules, so mypy is correct here in terms of static type-checking)
The following works, and is accepted by mypy, as expected
import cv2.typing
_ = cv2.typing.MatLike
The issue comes from importing both:
import cv2
import cv2.typing
Note that pyright handles this case correctly.
(A clear and concise description of what the bug is.)
To Reproduce
Download the reproduction, then run mypy . at the root. See error
Run python test.py, see the symbol printed out.
Minimal repro.zip
Expected Behavior
No error in repro
Actual Behavior
PS C:\Users\Avasam\Desktop\Minimal repro> mypy .
test.py:4: error: Module has no attribute "Foo" [attr-defined]
Found 1 error in 1 file (checked 3 source files)
Your Environment
- Mypy version used: mypy 1.5.1 (compiled: yes)
- Mypy command-line flags: None
- Mypy configuration options from
mypy.ini(and other config files): None - Python version used: Python 3.9.13
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Extract the linked Minimal repro.zip and first run mypy . from its root, then run python test.py to confirm the runtime behavior. Trace how mypy handles import cv2, import cv2.typing, and the later cv2.typing.MatLike access. Done means the reproduction reports no error while preserving the expected runtime result.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 45/100