python / python/mypy

`property` accessed on class incorrectly understood as function, expected `property`

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Description

class Foo:
    @property
    def foo(self) -> int:
        return 1

    reveal_type(foo)  # Revealed type is "def (self: asdf.Foo) -> int"


reveal_type(Foo.foo)  # Revealed type is "def (self: asdf.Foo) -> int"

related: https://github.com/python/mypy/issues/15911#issuecomment-1685167054

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the Foo reproducer in the issue and compare its two reveal_type results with the related discussion in mypy issue 15911. Trace how mypy interprets the @property declaration when accessed through the class, and consider the work complete when Foo.foo is revealed as a property rather than a function while instance access remains correct.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
35/100

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