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tuple[*Ts] subtype with extra type parameter not gradually assignable to itself #19908
Description
This demonstrates the issue:
from typing import Any
class Array[DataT, *ShapeTs](tuple[*ShapeTs]): ...
type Float2D = Array[float, *tuple[int, int]] # or Array[float, int, int]
type FloatND = Array[float, *tuple[Any, ...]]
def from_2d(a: Float2D) -> FloatND:
return a # mypy: ✅, pyright: ✅
def into_2d(a: FloatND) -> Float2D:
return a # mypy: ❌, pyright: ✅https://mypy-play.net/?mypy=latest&python=3.13&flags=strict&gist=1b95c702df6de35fa3f61aa7b5dfef16
Without the additional DataT typar, the false positive disappears
from typing import Any
class Array[*ShapeTs](tuple[*ShapeTs]): ...
type Float2D = Array[*tuple[int, int]] # or Array[int, int]
type FloatND = Array[*tuple[Any, ...]]
def from_2d(a: Float2D) -> FloatND:
return a # mypy: ✅, pyright: ✅
def into_2d(a: FloatND) -> Float2D:
return a # mypy: ✅, pyright: ✅https://mypy-play.net/?mypy=latest&python=3.13&flags=strict&gist=be0dfedeb0e7ed14da359cd52d2901e7
The issue also disappears when tuple is no longer a base class
from typing import Any
class Array[float, *ShapeTs]: ...
type Float2D = Array[float, *tuple[int, int]] # or Array[float, int, int]
type FloatND = Array[float, *tuple[Any, ...]]
def from_2d(a: Float2D) -> FloatND:
return a # mypy: ✅, pyright: ✅
def into_2d(a: FloatND) -> Float2D:
return a # mypy: ✅, pyright: ✅https://mypy-play.net/?mypy=latest&python=3.13&flags=strict&gist=a1439e7c3037239bc4663b981534fb17
Potentially related issues:
- Lenient TypeVarTuple checking when number of dimensions is unknown #18665
- incorrect inference of user-defined variadic tuple subtype instances #19106
tuple[Any, *tuple[Any, ...]]is not assignable to other tuple types #19109- Empty variadic
tuplesubtype not assignable totuple[int, ...]#19110 - Inconsistent constraint resolution for tuples. #19860
- false positive "Tuple index out of range" when indexing
tuple[Any, *tuple[Any, ...]]#19858
Activity
Lenient handling of *tuple[Any, ...] (part 1) (python#22001)