Summary
# getitem_bug.py
from collections.abc import Sequence
from operator import __getitem__, __index__
from typing import SupportsIndex, TypeVar, reveal_type
_T = TypeVar("_T")
def derpitem(seq: Sequence[_T], key: SupportsIndex) -> _T:
reveal_type(key) # SupportsIndex
reveal_type(__index__(key)) # int
return __getitem__(seq, __index__(key)) # <-- \\BOOM!//
print(list(derpitem("abcdefghi", 3)))Playground: https://play.ty.dev/bec872f4-361c-4fd3-9eb0-06e82164ca0b
% python getitem_bug.py
Runtime type is 'int'
Runtime type is 'int'
['d']
% mypy --config-file=/dev/null getitem_bug.py # <-- no error (similar to pyrefly and pyright)
/dev/null: No [mypy] section in config file
getitem_bug.py:10: note: Revealed type is "typing.SupportsIndex"
getitem_bug.py:11: note: Revealed type is "builtins.int"
Success: no issues found in 1 source file
% ty version
ty 0.0.22
% ty check --python-version 3.11 getitem_bug.py # <-- no likey
info[revealed-type]: Revealed type
--> getitem_bug.py:10:17
|
9 | def derpitem(seq: Sequence[_T], key: SupportsIndex) -> _T:
10 | reveal_type(key) # SupportsIndex
| ^^^ `SupportsIndex`
11 | reveal_type(__index__(key)) # int
12 | return __getitem__(seq, __index__(key)) # <-- \\BOOM!//
|
info[revealed-type]: Revealed type
--> getitem_bug.py:11:17
|
9 | def derpitem(seq: Sequence[_T], key: SupportsIndex) -> _T:
10 | reveal_type(key) # SupportsIndex
11 | reveal_type(__index__(key)) # int
| ^^^^^^^^^^^^^^ `int`
12 | return __getitem__(seq, __index__(key)) # <-- \\BOOM!//
|
error[no-matching-overload]: No overload of function `getitem` matches arguments
--> getitem_bug.py:12:12
|
10 | reveal_type(key) # SupportsIndex
11 | reveal_type(__index__(key)) # int
12 | return __getitem__(seq, __index__(key)) # <-- \\BOOM!//
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
info: First overload defined here
--> stdlib/_operator.pyi:164:5
|
162 | def delitem(a: MutableMapping[_K, Any], b: _K, /) -> None: ...
163 | @overload
164 | def getitem(a: Sequence[_T], b: slice[int | None], /) -> Sequence[_T]:
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
165 | """Same as a[b]."""
|
info: Possible overloads for function `getitem`:
info: [_T](a: Sequence[_T], b: slice[int | None, int | None, int | None], /) -> Sequence[_T]
info: [_K, _V](a: SupportsGetItem[_K, _V], b: _K, /) -> _V
info: rule `no-matching-overload` is enabled by default
Found 3 diagnosticsRelevant types:
Version
ty 0.0.22
Summary
Playground: https://play.ty.dev/bec872f4-361c-4fd3-9eb0-06e82164ca0b
Relevant types:
getitemoverloadsSupportsGetItemSupportsIndexVersion
ty 0.0.22