[stdlib] Update the return type of urllib.request.urlopen to urllib.response.addinfourl | http.client.HTTPResponse

[edgarrmondragon]

No description provided.

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

dulwich (https://github.com/dulwich/dulwich)
+ dulwich/lfs.py:690: error: Unsupported operand types for <= ("int" and "None")  [operator]
+ dulwich/lfs.py:690: note: Left operand is of type "int | None"
+ dulwich/lfs.py:705: error: Unsupported operand types for <= ("int" and "None")  [operator]
+ dulwich/lfs.py:705: note: Left operand is of type "int | None"

spack (https://github.com/spack/spack)
+ lib/spack/spack/test/oci/urlopen.py:448: error: Argument "_urlopen" to "upload_blob" has incompatible type "Callable[[str | Request, Buffer | SupportsRead[bytes] | Iterable[bytes] | None, float | None], addinfourl | HTTPResponse]"; expected "Callable[..., HTTPResponse] | None"  [arg-type]
+ lib/spack/spack/test/oci/urlopen.py:457: error: Argument "_urlopen" to "upload_blob" has incompatible type "Callable[[str | Request, Buffer | SupportsRead[bytes] | Iterable[bytes] | None, float | None], addinfourl | HTTPResponse]"; expected "Callable[..., HTTPResponse] | None"  [arg-type]
+ lib/spack/spack/test/oci/urlopen.py:467: error: Argument "_urlopen" to "upload_blob" has incompatible type "Callable[[str | Request, Buffer | SupportsRead[bytes] | Iterable[bytes] | None, float | None], addinfourl | HTTPResponse]"; expected "Callable[..., HTTPResponse] | None"  [arg-type]

archinstall (https://github.com/archlinux/archinstall)
+ archinstall/lib/packages/packages.py:27: error: Incompatible return value type (got "addinfourl | HTTPResponse", expected "addinfourl")  [return-value]

static-frame (https://github.com/static-frame/static-frame)
+ static_frame/core/www.py:225: error: Incompatible types in assignment (expression has type "Callable[[], bytes]", variable has type "Callable[[], str]")  [assignment]
+ static_frame/core/www.py:225: error: Incompatible return value type (got "bytes", expected "str")  [return-value]

operator (https://github.com/canonical/operator)
+ ops/pebble.py:2241: error: Incompatible return value type (got "addinfourl | HTTPResponse", expected "HTTPResponse")  [return-value]

[srittau]

Unfortunately, this would require every user of urlopen() to add a cast or isinstance check, so it's not feasible to change this. But it's a case where python/typing#566 would be useful. That said, we should add an appropriate comment to the type var, explaining the expected return types.

[edgarrmondragon]

Unfortunately, this would require every user of urlopen() to add a cast or isinstance check, so it's not feasible to change this. But it's a case where python/typing#566 would be useful.

Thanks @srittau, I see that now. Even in my own code which motivated this change, I'd need to add a type assertion to make it actually work after this change.

That said, we should add an appropriate comment to the type var, explaining the expected return types.

You mean to _UrlopenRet?

[srittau]

You mean to _UrlopenRet?

Yes. If you want to, you can change this PR accordingly. Otherwise, I'll add a comment.