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[1.16 regression] duplicated note for incompatible type #19240
Description
Bug Report
Note lines are being repeated when an error for an incompatible type is raised in certain cases.
Encountered when adding support for mypy v1.16 in typeddjango/django-stubs#2703
Bisected to #18847
To Reproduce
from django.db import models
class MyModel(models.Model):
char1 = models.CharField(max_length=200, choices="test")Expected Behavior
$ uvx --python=3.12 --with=django-stubs mypy==1.15 --strict bug.py
Installed 9 packages in 71ms
bug.py:5: error: Need type annotation for "char1" [var-annotated]
bug.py:5: error: Argument "choices" to "CharField" has incompatible type "str"; expected "Iterable[tuple[Any, Any] | tuple[str, Iterable[tuple[Any, Any]]]] | Mapping[Any, Any] | type[Choices] | Callable[[], Iterable[tuple[Any, Any] | tuple[str, Iterable[tuple[Any, Any]]]] | Mapping[Any, Any]] | None" [arg-type]
bug.py:5: note: Following member(s) of "str" have conflicts:
bug.py:5: note: Expected:
bug.py:5: note: def __iter__(self) -> Iterator[tuple[Any, Any] | tuple[str, Iterable[tuple[Any, Any]]]]
bug.py:5: note: Got:
bug.py:5: note: def __iter__(self) -> Iterator[str]
Found 2 errors in 1 file (checked 1 source file)Actual Behavior
$ uvx --with=django-stubs mypy==1.16 --strict bug.py
bug.py:5: error: Need type annotation for "char1" [var-annotated]
bug.py:5: error: Argument "choices" to "CharField" has incompatible type "str"; expected "Iterable[tuple[Any, Any] | tuple[str, Iterable[tuple[Any, Any]]]] | Mapping[Any, Any] | type[Choices] | Callable[[], Iterable[tuple[Any, Any] | tuple[str, Iterable[tuple[Any, Any]]]] | Mapping[Any, Any]] | None" [arg-type]
bug.py:5: note: Following member(s) of "str" have conflicts:
bug.py:5: note: Expected:
bug.py:5: note: def __iter__(self) -> Iterator[tuple[Any, Any] | tuple[str, Iterable[tuple[Any, Any]]]]
bug.py:5: note: Got:
bug.py:5: note: def __iter__(self) -> Iterator[str]
bug.py:5: note: Expected:
bug.py:5: note: def __iter__(self) -> Iterator[tuple[Any, Any] | tuple[str, Iterable[tuple[Any, Any]]]]
bug.py:5: note: Got:
bug.py:5: note: def __iter__(self) -> Iterator[str]
Found 2 errors in 1 file (checked 1 source file)Note that the last four "note" lines are repeated.
Your Environment
- Mypy version used: 1.16
- Mypy command-line flags: --strict
- Mypy configuration options from mypy.ini (and other config files): n/a
- Python version used: Python 3.12
Activity
ilevkivskyi commented on Jun 5, 2025
OK, I think I know what is going on:
Fix and simplify error de-duplication (#19247)