`TYPE_CHECKING` doesn't work if imported with alias

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#12,928 3 comments 2 reactions 0 assignees View on GitHub

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
42/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Stale
Tech stack
python
Domain
devtools

Research direction

Start by reproducing the discrepancy in the issue's Python snippet or linked mypy playground, then trace how mypy recognizes TYPE_CHECKING imports and aliases. Done means an aliased import behaves like the direct import for unreachable-code analysis, with regression coverage for both forms.

Written by the indexing model from the issue text.

Description

bug 
from typing import TYPE_CHECKING
from typing import TYPE_CHECKING as amogus

if not TYPE_CHECKING:
    1 + "" # no error (unreachable)
    
if not amogus:
    1 + "" # error

playground

Dominant language
Python
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Forks
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Avg merge
1d 18h
Merged PRs (30d)
54

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