python / python/mypy

`tuple` instantiation ignores generics

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#15,172 5 comments 3 reactions 0 assignees View on GitHub

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bug
Dominant language
Python
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Description

a = [1,2]
b: tuple[int, int] = tuple[int, int](a) # Incompatible types in assignment (expression has type "Tuple[int, ...]", variable has type "Tuple[int, int]")  [assignment]

playground

related: #15171

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Research direction

Reproduce the assignment error in the linked mypy playground, then compare the case with related issue #15171. Trace how mypy analyzes generic tuple instantiation; done means the example no longer treats tupleint, int as Tuple[int, ...] when the generic form specifies a fixed-length tuple.

Written by the indexing model from the issue text.

Assessment

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

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