[CI] Panic in mypy_primer

[stroxler]

Describe the Bug

Recent PRs have a panic, it looks like a Var leak in shard 7

Sandbox Link

No response

(Only applicable for extension issues) IDE Information

No response

[rchen152]

I constructed a standalone repro for the issue:

# foo.py
from enum import Enum
from typing import Self
class E(Enum):
    A = frozenset({1})
    B = frozenset({2})
    @classmethod
    def from_ord(cls) -> list[Self]:
        return [v for v in cls]

# bar.py
from foo import E
def f() -> None:
    xs = E.from_ord()
    _ = [x for x in xs if x != E.A]

pyrefly check bar.py crashes. Given that enums seem to be involved, and this comment says that failing to visit all Type fields is a cause of var leaks, I wonder if 350bac2 could be related.