request-cache with --no-implicit-reexport cause an AssertionError

[p-gag]

Crash Report

Only with --no-implicit-reexport, adding from requests_cache import CachedSession into any file, including an empty file cause this error: AssertionError: Definition of requests_cache.patcher.BaseCache is unexpectedly incomplete

Traceback

$ mypy --no-implicit-reexport app/test.py
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.9/bin/mypy", line 8, in <module>
    sys.exit(console_entry())
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/mypy/__main__.py", line 11, in console_entry
    main(None, sys.stdout, sys.stderr)
  File "mypy/main.py", line 87, in main
  File "mypy/main.py", line 165, in run_build
  File "mypy/build.py", line 179, in build
  File "mypy/build.py", line 254, in _build
  File "mypy/build.py", line 2697, in dispatch
  File "mypy/build.py", line 3021, in process_graph
  File "mypy/build.py", line 3138, in process_stale_scc
  File "mypy/build.py", line 2288, in write_cache
  File "mypy/build.py", line 1475, in write_cache
  File "mypy/nodes.py", line 313, in serialize
  File "mypy/nodes.py", line 3149, in serialize
  File "mypy/nodes.py", line 3083, in serialize
AssertionError: Definition of requests_cache.patcher.BaseCache is unexpectedly incomplete```

To Reproduce

# test.py
from requests_cache import CachedSession

On the command line:

$ mypy --no-implicit-reexport test.py

Note: removing the .mypy_chache did not help.

Your Environment

• request-cache used: 0.7.3
• Mypy version used: 0.910
• Mypy command-line flags: --no-implicit-reexport
• Mypy configuration options from mypy.ini (and other config files): not used
• Python version used: 3.9.1
• Operating system and version: macOS Version 11.3.1

[JWCook]

Well, that's curious. I also reproduced this with the latest changes in the requests-cache master branch.

If I modify the import in requests_cache/patcher.py to

from .backends import BaseCache as BaseCache

The error goes away, but if I alias it to something else:

from .backends import BaseCache as CacheType

I get the same AssertionError.

I don't know what's going on there, but if you have suggestions for improving the type hints or exports in requests-cache, you're welcome to create an issue there: https://github.com/reclosedev/requests-cache/issues

[boehmseb]

Hi,

I just stumbled across the same problem. While I also have no idea what's going on, I can say that mypy only crashes from version 0.800 onwards. No crash with earlier versions. Maybe this helps identifying the problem.