CV2 stub defines type aliases with circular references

[erictraut]

The cv2/__init__.pyi defines several type aliases that are invalid because they refer to themselves. This leaves them Unknown.

Here are a few examples:

VariationalRefinement = _mod_cv2.VariationalRefinement
VideoCapture = _mod_cv2.VideoCapture
VideoWriter = _mod_cv2.VideoWriter

Since _mod_cv2 refers back to this same type stub, these are effectively equivalent to:

VariationalRefinement = VariationalRefinement
VideoCapture = VideoCapture
VideoWriter = VideoWriter

Pyright correctly flags these as errors in the stub. They should be fixed.

[Avasam]

For anyone else landing here:

Given that opencv can now generates python stubs and opencv-python has been updated to ship them, you can try the in-development version using pip install git+https://github.com/opencv/opencv-python.git.

You can set the appropriate environment variables first if you'd like to install a specific package (like headless, contrib or healdless-contrib):

ENABLE_CONTRIB=1
ENABLE_HEADLESS=1

It should work as-is with pyright and mypy, but for Pylance you'll have to remove the bundled stubs every time you update the extension. It can be found at: %HOMEPATH%\.vscode\extensions\ms-python.vscode-pylance-<VERSION>\dist\bundled\stubs\cv2-stubs (where <VERSION> is your current Pylance version).

If you have an issue with those generated stubs, you can raise it upstream.