Bad circular imports are not rejected

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#61 12 comments 3 reactions 0 assignees View on GitHub

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
30/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
python
Domain
compilers

Research direction

Start by reproducing the issue with the a.py and b.py examples given in the report, then trace how mypy handles their imports. Define the intended diagnostic and add a regression case showing that the circular import is rejected without allowing invalid generated Python to pass.

Written by the indexing model from the issue text.

Description

feature priority-2-low topic-runtime-semantics

If a.py contains

import b
name = 'a'
print(b.name)

and b.py contains

import a
name = 'b'
print(a.name)

then mypy compiles a.py without error, but the generated python throws an error because of the circular import.

(Found this one while refactoring mypy itself into packages)

Dominant language
Python
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Avg merge
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Merged PRs (30d)
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