Bug in alias annotations #7184
Description
Environment data
- pyright 1.1.349
- python version 3.11.6
Code snippet
from typing import Generic
from typing import Literal
from typing import TypeAlias
from typing import TypeVar
A_float: TypeAlias = Literal["float32", "float64"]
A_numeric: TypeAlias = Literal["int32", "int64"] | A_float
Tdtype = TypeVar("Tdtype", bound=A_numeric)
class TypedArray(Generic[Tdtype]):
pass
Tdtype_float = TypeVar("Tdtype_float", bound=A_float)
# WORKS
OptionalFloatArray: TypeAlias = TypedArray[Tdtype_float] | None
# FAILS but equivalent
OptionalArray: TypeAlias = TypedArray[Tdtype] | None
OptionalFloatArray_: TypeAlias = OptionalArray[Tdtype_float]
# error: Could not specialize type "OptionalArray[Tdtype@OptionalArray]"
# "Literal['float32']" cannot be assigned to type "Literal['int32']"
# "Literal['float64']" cannot be assigned to type "Literal['int64']"Error description
Valid aliases with TypeVars raise error if Literal bounds are narrowed.
- Seems to only happen when using Literals in both bounds
- Does not happen if there is only one Literal in
A_float - Error description indicates that the bug is caused by doing subtype comparison in the wrong order