match/case doesn't perform overlapping equality checking

[jgarvin]

Even with --strict this is accepted:

match 3:
    case "hello":
        pass

While this is rejected:

if 3 == "hello":
    pass

[socketpair]

Definitely not a bug. Because comparing patterns in match/case is not just comparing values. Pylint I think could say something about unreachability, but regarding types - MyPy is handling this case correctly.

[socketpair]

@JelleZijlstra close as "not a bug"

[JelleZijlstra]

I already removed the "bug" label :)

As the original report said, mypy warns you about == usages between two types with no overlap. It's a reasonable extension to also warn about match cases that do not overlap and therefore can never match.

[socketpair]

In principle... I agree. Okay.

[hauntsaninja]

mypy will complain about this with --warn-unreachable