Internal error with custom module

[nkakouros]

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  BUG

In my project, I have lib folder where I have placed some custom modules. The directory looks like this:

src/lib/python/
├── canvas
│   ├── announcements.py
│   ├── api_interface.py
│   ├── canvas_config.py
│   ├── course.py
│   ├── groups.py
│   ├── independent_group_discussions.py
│   ├── __init__.py
│   └── pages.py
├── cds
│   ├── canary
│   │   ├── canary_trap.py
│   │   └── __init__.py
│   ├── executor
│   │   ├── executor.py
│   │   └── __init__.py
│   ├── querier
│   │   ├── backends
│   │   │   ├── elasticsearch
│   │   │   │   ├── es_querier.py
│   │   │   │   └── queries
│   │   │   │       ├── canary
│   │   │   │       │   ├── command.py
│   │   │   │       │   └── packet.py
│   │   │   │       ├── __init__.py
│   │   │   │       ├── misc.py
│   │   │   │       └── player.py
│   │   │   └── stub
│   │   │       ├── queries
│   │   │       │   └── __init__.py
│   │   │       └── stub_querier.py
│   │   ├── __init__.py
│   │   ├── querier.py
│   │   ├── queries.py
│   │   └── query.py
│   └── splicer.py
├── twmn
│   ├── player.py
│   ├── scenario.py
│   ├── scoreboard
│   │   ├── backends
│   │   │   ├── canvas.py
│   │   │   └── mock.py
│   │   ├── __init__.py
│   │   └── scoreboard.py
│   ├── system.py
│   ├── theme.py
│   └── world.py
└── twmn_helpers
    ├── cdag.py
    ├── dotdict.py
    ├── errors.py
    └── logging.py

I have set PYTHONPATH to:

export PYTHONPATH="$PYTHONPATH:$PWD/src/lib/python"

Similarly, I have set MYPYPATH to:

export MYPYPATH="$PWD/src/lib/python/"

Without setting MYPYPATH, I do not get proper warnings for type mismatches for my custom modules.

The file cds/querier/query.py contains:

#!/usr/bin/env python

from abc import ABCMeta, abstractmethod


class Query(ABCMeta):
    @abstractmethod
    def __init__(self, query):
        pass

Then, I copy this file to /tmp/shadow.py and run:

mypy --config-file mypy.cfg /absolute/path/to/src/lib/python/cds/querier/query.py  --shadow-file /absolute/or/relative/path/to/src/lib/python/cds/querier/query.py /tmp/shadow.py

(I am replicating how my editor calls mypy to perform linting.)

This gives an internal error:

src/lib/python/cds/querier/query.py:8: error: Function is missing a type annotation
/absolute/path/to/src/lib/python/cds/querier/query.py:7: error: INTERNAL ERROR -- Please try using mypy master on Github:
https://mypy.rtfd.io/en/latest/common_issues.html#using-a-development-mypy-build
Please report a bug at https://github.com/python/mypy/issues
version: 0.770
Traceback (most recent call last):
  File "mypy/checker.py", line 401, in accept
  File "mypy/nodes.py", line 766, in accept
  File "mypy/checker.py", line 3516, in visit_decorator
  File "mypy/checker.py", line 792, in check_func_item
  File "mypy/checker.py", line 835, in check_func_def
  File "mypy/checker.py", line 1060, in check_for_missing_annotations
  File "mypy/checker.py", line 4767, in fail
  File "mypy/messages.py", line 180, in fail
  File "mypy/messages.py", line 165, in report
  File "mypy/errors.py", line 319, in report
  File "mypy/errors.py", line 350, in add_error_info
  File "mypy/errors.py", line 322, in _add_error_info
AssertionError: 
/absolute/path/to/src/lib/python/cds/querier/query.py:7: : note: use --pdb to drop into pdb

If I replace in the mypy command the absolute path to the file with the relative path, then mypy works ok:

mypy --config-file mypy.cfg src/lib/python/cds/querier/query.py  --shadow-file /absolute/or/relative/path/to/src/lib/python/cds/querier/query.py /tmp/shadow.py

I have tried with the latest development version and I get the same behavior.

[msullivan]

The issue is probably that your MYPYPATH overlaps with the files you are passing to the command line, which triggers a crash. The issue is #4881, so I'm closing this as a dupe of that.

There was a PR to fix that (#7567) that stalled out for no particularly good reason. I'll try to get that merged since it is pretty bad.