python / python/mypy

type of variable not narrowed after `continue` statement inside `try`/`except` block inside a for loop inside a function

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#18,466 1 comment 2 reactions 0 assignees View on GitHub

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bug topic-type-narrowing
Dominant language
Python
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Forks
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Description

def _() -> None:
    for value in [1,2]:
        try:
            foo = 1
        except Exception:
            foo = None
            continue
        reveal_type(foo) # `int | None`, should be `int`

playground

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the example in the linked mypy playground and inspect the control-flow type narrowing around the for loop, try/except, and continue statement. Add a regression test for this case; done means reveal_type(foo) is reported as int after the try/except block.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
compilers
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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