iter(type(enum_instance)) loses type information

[asottile]

Bug Report

(this is extracted from a larger example)

from __future__ import annotations

import enum


class E(enum.Enum):
    A = (1,)
    B = (2,)

    @property
    def x(self) -> E:
        reveal_type(type(self).__iter__)
        reveal_type(iter(type(self)))
        reveal_type(tuple(type(self)))
        vals = tuple(type(self))
        return vals[(vals.index(self) + 1) % len(vals)]


reveal_type(iter(E))

To Reproduce

1. mypy t.py

Expected Behavior

I expect:

$ mypy t.py
t.py:12: note: Revealed type is "def () -> typing.Iterator[t.E*]"
t.py:13: note: Revealed type is "typing.Iterator[t.E*]"
t.py:14: note: Revealed type is "builtins.tuple[t.E*, ...]"
t.py:19: note: Revealed type is "typing.Iterator[t.E*]"
Found 1 error in 1 file (checked 1 source file)

notably, iter(type(self)) should be Iterator[t.E*]

even adding self: E explicitly does not change the output

oddly enough, iter(E) correctly inferences the iterator type

Actual Behavior

$ mypy t.py
t.py:12: note: Revealed type is "def () -> typing.Iterator[t.E*]"
t.py:13: note: Revealed type is "typing.Iterator[<nothing>]"
t.py:14: note: Revealed type is "builtins.tuple[<nothing>]"
t.py:15: error: Need type annotation for "vals"
t.py:19: note: Revealed type is "typing.Iterator[t.E*]"
Found 1 error in 1 file (checked 1 source file)

(Write what happened.)

Your Environment

• Mypy version used: 0.920
• Mypy command-line flags: N/A
• Mypy configuration options from mypy.ini (and other config files): N/A
• Python version used: 3.8.10
• Operating system and version: ubuntu 20.04

[erictraut]

It appears this bug has been fixed. Mypy 1.5 produces the "expected results" above. These results agree with pyright as well.

[asottile]

nice! confirmed as well