Expected Iterable[Buffer] when using map(str, ...) #2087
Description
Summary
playground link: https://play.ty.dev/eab57770-64e1-44c8-940a-561b4340e9af
Consider the following program
from typing import Sequence, reveal_type
def test(command: Sequence[str]) -> None:
if isinstance(command, list):
reveal_type(command)
print(list(map(str, command)))
test(['echo', 'hello'])This works in runtime, however since 0.0.3, ty is reporting a type error
$ uv run --with ty==0.0.3 -m ty check test.py
info[revealed-type]: Revealed type
--> test.py:5:21
|
3 | def test(command: Sequence[str]) -> None:
4 | if isinstance(command, list):
5 | reveal_type(command)
| ^^^^^^^ `Sequence[str] & Top[list[Unknown]]`
6 | print(list(map(str, command)))
|
error[invalid-argument-type]: Argument to function `__new__` is incorrect
--> test.py:6:29
|
4 | if isinstance(command, list):
5 | reveal_type(command)
6 | print(list(map(str, command)))
| ^^^^^^^ Expected `Iterable[Buffer]`, found `Sequence[str] & Top[list[Unknown]]`
7 |
8 | test(['echo', 'hello'])
|
info: Matching overload defined here
--> stdlib/builtins.pyi:3839:13
|
3837 | else:
3838 | @overload
3839 | def __new__(cls, func: Callable[[_T1], _S], iterable: Iterable[_T1], /) -> Self: ...
| ^^^^^^^ ----------------------- Parameter declared here
3840 | @overload
3841 | def __new__(cls, func: Callable[[_T1, _T2], _S], iterable: Iterable[_T1], iter2: Iterable[_T2], /) -> Self: ...
|
info: Non-matching overloads for function `__new__`:
info: (cls, func: (_T1@__new__, _T2@__new__, /) -> _S@map, iterable: Iterable[_T1@__new__], iter2: Iterable[_T2@__new__], /) -> Self@__new__
info: (cls, func: (_T1@__new__, _T2@__new__, _T3@__new__, /) -> _S@map, iterable: Iterable[_T1@__new__], iter2: Iterable[_T2@__new__], iter3: Iterable[_T3@__new__], /) -> Self@__new__
info: (cls, func: (_T1@__new__, _T2@__new__, _T3@__new__, _T4@__new__, /) -> _S@map, iterable: Iterable[_T1@__new__], iter2: Iterable[_T2@__new__], iter3: Iterable[_T3@__new__], iter4: Iterable[_T4@__new__], /) -> Self@__new__
info: (cls, func: (_T1@__new__, _T2@__new__, _T3@__new__, _T4@__new__, _T5@__new__, /) -> _S@map, iterable: Iterable[_T1@__new__], iter2: Iterable[_T2@__new__], iter3: Iterable[_T3@__new__], iter4: Iterable[_T4@__new__], iter5: Iterable[_T5@__new__], /) -> Self@__new__
info: (cls, func: (...) -> _S@map, iterable: Iterable[Any], iter2: Iterable[Any], iter3: Iterable[Any], iter4: Iterable[Any], iter5: Iterable[Any], iter6: Iterable[Any], /, *iterables: Iterable[Any]) -> Self@__new__
info: rule `invalid-argument-type` is enabled by default
Found 2 diagnostics
This only started happening in 0.0.3; 0.0.2 works without type error. Interesting enough, on 0.0.2 reveal_type still shows Sequence[str] & Top[list[Unknown]], so felt like possible typeshed change? But doesn't look like there've been any recent typeshed syncs, so not sure what to make of it! https://github.com/astral-sh/ruff/commits/main/
Funny enough, if we change to isinstance(command, list[str]), this type checks in 0.0.3
4 | if isinstance(command, list[str]):
5 | reveal_type(command)
| ^^^^^^^ `Sequence[str]`
However
- it's not allowed in runtime:
TypeError: isinstance() argument 2 cannot be a parameterized generic - the inferred type isn't correct, should be
list[str]? (I guess this is irrelevant since ideally ty would flag this as invalid in runtime anyway)
Apologies if it's an existing issue, didn't really manage to find anything similar, and encountered independently in two separate projects, so figured worth reporting so people can find it in search.
Version
ty 0.0.3/latest master