Kai (Kazuya Ito)

An empty generic class is covariant even though the doc says "all user-defined generic classes invariant by default"

3

*Memo: - `mypy --strict test.py` - mypy 1.19.0 - Python 3.14.0 - Windows 11 [Invariance vs covariance](https://mypy.readthedocs.io/en/stable/common_issues.html#invariance-vs-covariance) says **_mypy considers all user-defined generic classes invariant by default_** as shown below:...

`bool` is available even if `*constraints` of `TypeVar` is the exact types `int` and `float`

4

*Memo: - `mypy --strict test.py` - mypy 1.18.2 - Python 3.14.0 - Windows 11 [The doc](https://docs.python.org/3/library/typing.html#typing.TypeVar) says **'Must be exactly str or bytes'** about `*constraints` to make difference between `bound`...

Lint against cases where user likely intended to use constrained type variables

2

*Memo: - `mypy test.py` - mypy 1.18.2 - Python 3.14.0 - Windows 11 Instantiating the object of the class with the wrong syntax setting constraint types to the 2nd and...