Repository navigation
tuple index out of range error is inconsistent #20475
Description
Either both of these should error, or neither of them.
def test1(items: tuple[int, ...]) -> None:
reveal_type(items[1]) # ✅️
reveal_type(items[2]) # ✅️
reveal_type(items[3]) # ✅️
def test2(items: tuple[int, *tuple[int, ...]]) -> None:
reveal_type(items[1]) # ❌️ tuple index out of range
reveal_type(items[2]) # ❌️ tuple index out of range
reveal_type(items[3]) # ❌️ tuple index out of rangehttps://mypy-play.net/?mypy=master&python=3.12&gist=dc9de67cb18ae540cdbb6bc32632eae7
FWIW, only mypy errors here. pyright (strict): no errors, pyrefly no errors, ty: no errors.
Such tuple types can occur naturally, which makes this check prone to false positives, for instance tup=(id, *values), when values is list-like.
Activity
randolf-scholz commented on Dec 26, 2025
Looks to be a duplicate of #19109 and #18665.
I encountered this as a result of my draft PR #20472, which introduces more precise tuple handling, that can introduce tuple[T, *tuple[...]] for instance from handling unions of tuples.