[carljm]

At runtime on Python 3.15, frozendict defines its own __eq__ and __ne__ types, which require self to be a frozendict. With this correctly reflected in typeshed, type-checkers can catch the runtime TypeErrors below, which otherwise pass silently:

plain = {"x": 1}
frozen = frozendict(plain)

assert frozendict.__eq__(frozen, plain)  # True
frozendict.__eq__(plain, frozen)         # TypeError
frozendict.__ne__(plain, frozen)         # TypeError

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉