Uncaught Error in Assignment of type Iterator[int] to type Iterator[str]

Bug Report

Mypy allows the assignment
it: Iterator[str] = iter(d) where d is dict[int, str].

To Reproduce

https://mypy-play.net/?mypy=latest&python=3.12&flags=strict&gist=05c55a654acd175b763be1c73567a107

from typing import Iterator


d: dict[int, str] = {1: 'A'}
it: Iterator[str] = iter(d)  # mypy does not complain, although iter(d) has type Iterator[int]!
s = next(it) + 'foo'  # TypeError: unsupported operand type(s) for +: 'int' and 'str'

Expected Behavior

Mypy raises an error such as
error: Argument 1 to "iter" has incompatible type "dict[int, str]"; expected "SupportsIter[Iterator[str]]"

Actual Behavior

Success: no issues found in 1 source file

Your Environment

mypy Playground

• Mypy version used: mypy latest 1.17.1
• Mypy command-line flags: --strict
• Python version used: 3.12

Inizia con il riproduttore collegato di mypy-play.net e l’espressione iter(d), usando mypy 1.17.1 con --strict su Python 3.12. Traccia il modo in cui il type checker inferisce il tipo dell’iteratore per un dict[int, str] e aggiungi un test di regressione che mostri che l’assegnazione a Iterator[str] viene rifiutata.