Improve error code linkability

[Avasam]

Documentation

In microsoft/vscode-mypy#58, I'm adding the functionality to link to specific mypy error code documentation. However, there's two issues affecting maintainability:

• The error codes span 2 pages
• The anchors are autogenerated from titles

Which leads to having to keep a map of all code-to-url, like this:
https://github.com/microsoft/vscode-mypy/pull/58/files#diff-3c2e579f59d8e749f5527d64f087396907db30414fe139bc91a1ecce9f9613ddR22

I would prefer if it was possible to programmatically link to mypy error codes documentation with only the information given by the mypy/dmypy CLI. Redirection is an acceptable solution to me.

[Avasam]

FWIW, if I can get the "Error codes enabled by default" from the mypy CLI, that solves the first point.
The second one should be solvable with custom RST anchors. https://sublime-and-sphinx-guide.readthedocs.io/en/latest/references.html#use-a-custom-anchor

[ikonst]

Yes, if our error codes pages had custom anchors instead of the autogenerated one, it'd help.

Random thought - perhaps there's a Sphinx extension, or one could be easily built, to redirect anchors (which should be unique within the docs) to the right page / anchor?

[ilevkivskyi]

Note btw there is also #7186 I think it is a good idea to add direct short links. I am quite sure we can write a Sphinx extension for this.

[ilevkivskyi]

OK, so here is the proposed fix #15435

[Avasam]

Note btw there is also #7186 I think it is a good idea to add direct short links. I am quite sure we can write a Sphinx extension for this.

I missed that. This is basically a duplicate. I'm essentially asking for the same thing.

[ilevkivskyi]

OK, I guess I actually broke the readthedocs build. Everything works locally and in CI because mypy is available there, but likely not available in readthedocs build env. I will submit a follow-up PR to only verify the error code completeness in tests.

[ilevkivskyi]

#15437 should fix the build.

[ilevkivskyi]

OK, this is now available in latest: https://mypy.readthedocs.io/en/latest/_refs.html#code-union-attr