Handle Self wrapped in Annotated when checking the expected self type - #21928
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ilevkivskyi merged 2 commits intoSep 8, 2026
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A5rocks
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I'm surprised we don't already simply trim out Annotated in all types! But this makes sense to me otherwise.
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Out of curiosity(not entirely sure if it's actually an issue), while snooping around to fix this issue, I noticed mypy is okay with this: class Foo:
def fails[T: Self](self: Annotated[T, "tag"], x: int) -> None: passI might be missing a lot of things since I'm fairly new to type checking semantics, but I think I couldn't find anything about this in PEP 673, and no other type checker allows this(I tried pyright, zuban, and ty). Is this intended on mypy's side? |
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I've also found that the following has the same issue: from typing import Self
type Test[T] = T
class Foo:
# error: Method cannot have explicit self annotation and Self type [misc]
def also_fails(self: Test[Self], x: int) -> None: passNot a practical issue but it does seem odd. |
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According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅ |
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Fixes #21917
Self wrapped in Annotated was not being recognized as an expected self type. This PR updates
is_expected_self_typeto recurse through Annotated when checking unbound types.