valid-type not reported for variables imported in other modules

[njgrisafi]

Bug Report

Mypy reports [valid-type] for a variable defined in the same file but not when the variable is imported in other files.

To Reproduce

Create 3 files

# app/example_a.py

def dynamic_type(x):
    return type("some_type", () , x)

# app/example_b.py

from app.example_a import dynamic_type

SOME_FAKE_TYPE = dynamic_type({"a": "a"})

x: SOME_FAKE_TYPE

# app/example_c.py
from app.example_b import SOME_FAKE_TYPE


x: SOME_FAKE_TYPE

Expected Behavior

Mypy should raise [valid-type] errors in both app/example_b.py and app/example_c.py

Actual Behavior

It only reports [valid-type] errors in app/example_b.py

app/example_b.py:6: error: Variable "app.example_b.SOME_FAKE_TYPE" is not valid as a type  [valid-type]
app/example_b.py:6: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#variables-vs-type-aliases

Your Environment

$ uv run mypy --version
mypy 1.16.0 (compiled: yes

• Mypy version used: 1.16.0
• Mypy command-line flags: mypy
• Mypy configuration options from mypy.ini (and other config files):

[mypy]
check_untyped_defs = True
follow_imports = normal
disallow_untyped_defs = False
files = app/

• Python version used: 3.11.8

[njgrisafi]

Adding a return annotation makes mypy behave the way we expect

from typing import Any

def dynamic_type(x) -> type[Any]:
    return type("some_type", () , x)

[hauntsaninja]

The intention here is similar to complaining about symbols that mypy cannot resolve from imports. It makes mypy complain if you're using annotations in a bunch of places (and so may expect actually meaningful type checking) but the annotation doesn't mean anything to mypy (and so there is no meaningful type checking)

I wouldn't make any behaviour changes to mypy here, but I'd we could maybe consider a sub error-code for valid-type specific to Any