Warning for "always False" reference checking?

[Holt59]

I just noticed that pyright does not warn for improper use of is between variables of different types, e.g.

def f(x: dict[int, float], y: float):
    if y is x:  # <- no warning/error here
        print("foo?")

Is there a reason for that? Is there a way to enable such warning?

I am asking because I just spend some times because I misspelled is instead of in, so that would have been useful.

[erictraut]

No one has ever requested such a feature before. I don't recall seeing any such request in the mypy issue tracker either, so this must be a relatively uncommon situation.

I'd consider adding such a feature if there's enough signal from pyright users that it would be useful. If you run across this thread and would like to see such a feature added, please add a "thumbs up" reaction.