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Importing a new file within a module using "from x import y" fails in incremental mode #1848
Description
Consider the following test case:
[case testIncrementalFoo]
from parent import a
[file parent/__init__.py]
[file parent/a.py]
[file parent/a.py.next]
from parent import b
[file parent/b.py.next]
[stale parent.a, parent.b]
[out]It initially starts with two files (parent/__init__.py and parent/a.py) that are both empty, then runs mypy -i -c "from parent import a" to warm up the cache.
We then add a new empty file, parent/b.py, and change parent/a.py to contain the single line from parent import b and re-run mypy -i -c "from parent import a".
The expected behavior is that mypy should typecheck the modified files without complaining, but will instead report the following error:
<string>:1: note: In module imported here:
parent/a.py:1: error: Module has no attribute 'b'
This error disappears when we change parent/a.py to contain either the line import parent.b or import parent.b as b, or if the file parent/b.py existed before mypy was first run.
Activity
gvanrossum commentedon Jul 12, 2016
Michael0x2a commentedon Jul 12, 2016
It seems like making the dummy change does make the problem go away, as you predicted :)
I'll look into the caching logic next then.
Add failing test case demonstrating bug
Correctly handle ImportFrom in incremental mode