Description
This bug found via a report from @eddieschoute
mypy crashes on the following cmdline test:
[case testDuplicateModules]
# cmd: mypy src
[file mypy.ini]
[[mypy]
mypy_path = src
[file src/__init__.py]
[file src/a.py]
import foo.bar
[file src/foo/__init__.py]
[file src/foo/bar.py]
1+'x'
[out]
-- The below would be what we produced if it didn't crash, but really we should
-- produce a useful error.
src/foo/bar.py:1: error: Unsupported operand types for + ("int" and "str")
src/foo/bar.py:1: error: Unsupported operand types for + ("int" and "str")
This crashes with
File "/home/msullivan/src/mypy/mypy/errors.py", line 264, in _add_error_info
assert file not in self.flushed_files
Here, the "canonical" module name for src/foo/bar.py is src.foo.bar. But if src is on the search path, both python and mypy will also happily let it have the name foo.bar.
In the test above, the inclusion on the command line results in bar.py being processed as src.foo.bar while the import for foo.bar in a.py, combined with src being on the mypy_path, also leads to it being processed as foo.bar. An error is generated in both, which trips an assert in Errors as we try to add a new error to a file that has already had its error messages flushed to the user.
One simple fix would be to track flushed_files by module id instead of file name, but it would probably be better to generate an error when a file appears multiple times with different module names, since it is unlikely to be intended?