Generate a warning/error on assigning values of type NoReturn

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#4,179 6 comments 0 reactions 0 assignees View on GitHub

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Assessment

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

Research direction

Start with the Python example in the issue and investigate how mypy handles an expression annotated as NoReturn when its value is assigned. No source file or test is named, so locate the relevant type-checking entry point and existing NoReturn tests; done means the example produces the requested warning or error with appropriate coverage.

Written by the indexing model from the issue text.

Description

feature priority-2-low 
import sys
from typing import List
from mypy_extensions import NoReturn

def never_returns() -> NoReturn:
    sys.exit(1)

def foo() -> None:
    x = never_returns()

It would be nice if mypy warned in this situation.

Dominant language
Python
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Avg merge
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Merged PRs (30d)
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