valid-type not reported for variables imported in other modules
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Description
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
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the report with app/example_a.py, app/example_b.py, and app/example_c.py using mypy 1.16.0, then compare the [valid-type] diagnostics for the local and imported variables. The fix is complete when mypy reports the expected error in both example_b.py and example_c.py without changing the reproduction’s intent.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100