`type A[T] = T; reveal_type(A[int])` shows `typing.TypeAliasType` rather than `types.GenericAlias`
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bug
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- Python
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Description
type A[T] = T
reveal_type(A[int]) # ❌ typing.TypeAliasType
yet
>>> type A[T] = T
>>> type(A[int])
<class 'types.GenericAlias'>
on master and v1.18.2
https://mypy-play.net/?mypy=latest&python=3.12&gist=fa2132200cfca28caf586f0ccc5dc26c
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the example in the linked mypy playground on Python 3.12 and compare mypy's reveal_type result with the runtime type shown in the issue. The work is done when the generic type alias expression is reported consistently with its runtime types.GenericAlias result.
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
- Mostly clear
- Newbie friendliness
- 45/100