generics handle default argument incorrectly #16219
Description
Bug Report
Mypy doesn't appear to handle generic parameters with default values correctly.
To Reproduce
from typing import TypeVar, reveal_type
import numpy as np
from numpy.typing import NBitBase, NDArray
T = TypeVar("T", bound=NBitBase)
def func(dtype: type[np.floating[T]] = np.float64) -> NDArray[np.floating[T]]: # error: Incompatible default for argument "dtype" (default has type "type[floating[Any]]", argument has type "type[floating[T]]") [assignment]
return np.empty(1, dtype)
reveal_type(func()) # Revealed type is "numpy.ndarray[Any, numpy.dtype[numpy.floating[<nothing>]]]"
reveal_type(func(np.float32)) # Revealed type is "numpy.ndarray[Any, numpy.dtype[numpy.floating[numpy._typing._32Bit]]]"Expected Behavior
scratch.py:11: note: Revealed type is "numpy.ndarray[Any, numpy.dtype[numpy.floating[numpy._typing._64Bit]]]"
scratch.py:12: note: Revealed type is "numpy.ndarray[Any, numpy.dtype[numpy.floating[numpy._typing._32Bit]]]"
Actual Behavior
scratch.py:8: error: Incompatible default for argument "dtype" (default has type "type[floating[Any]]", argument has type "type[floating[T]]") [assignment]
scratch.py:11: note: Revealed type is "numpy.ndarray[Any, numpy.dtype[numpy.floating[<nothing>]]]"
scratch.py:12: note: Revealed type is "numpy.ndarray[Any, numpy.dtype[numpy.floating[numpy._typing._32Bit]]]"
Found 1 error in 1 file (checked 1 source file)
Your Environment
- Mypy version used: 1.5.1
- Mypy command-line flags: none
- Mypy configuration options from
mypy.ini(and other config files): none - Python version used: 3.11.5
$ .venv/bin/pip freeze
mypy==1.5.1
mypy-extensions==1.0.0
numpy==1.26.0
typing_extensions==4.8.0