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The global___ name mangling breaks my type check

See original GitHub issue

With mypy-protobuf 1.19, mypy passed my code. Upgrading to mypy-protobuf 1.20 changes the output to add some global___ prefixes to types, breaking the type check. If I pin my dependency to 1.19, or just strip out these prefixes, mypy passes my code again. Is there another alternative? Perhaps an option to disable the name mangling?

Issue Analytics

State:
Created 3 years ago
Reactions:1
Comments:9 (5 by maintainers)

Top GitHub Comments

1reaction

nipunn1313commented, Jun 11, 2020

Excellent debugging! Thanks!

I changed global__ to type__ since it was not actually always at global scope - while I was investigating this issue earlier.

We do have a test case which creates a similar scenario here.

proto: https://github.com/dropbox/mypy-protobuf/blob/master/proto/test/proto/test3.proto#L32

generated pyi: https://github.com/dropbox/mypy-protobuf/blob/master/test/proto/test3_pb2.pyi.expected#L97

This seems to pass our tests, which does mypy over the generated .pyi file. This leads me to suspect something more complex is going on than just the snippits pasted.

These links are both to version 1.22 (not yet released). Going back in time to version 1.21, the file looks like this

https://github.com/dropbox/mypy-protobuf/blob/3cd710c3346eb65c33e64107891299f173e58b82/test/proto/test3_pb2.pyi.expected#L114

Potential hypotheses (guessing based on what might be different):

Mypy version? Our tests (back at 1.21) ran against mypy 0.761 Our tests (on master, soon to be 1.22) run against mypy 0.780

Different mypy flags? Our instantiation (pretty vanilla) https://github.com/dropbox/mypy-protobuf/blob/master/run_test.sh#L40 https://github.com/dropbox/mypy-protobuf/blob/master/mypy.ini

Different test case? Perhaps paste your entire .pyi file as generated here? Dumping your test case into mypy-playground, it appears to pass https://mypy-play.net/?mypy=latest&python=3.8&gist=4002b2b37938f880a515a836af5c7ada

Oooh interesting!! I think mypy version is to blame here. Somewhere between 0.750 https://mypy-play.net/?mypy=0.750&python=3.8&gist=b605afaed49a278a76deed5fbc7f8439 And 0.760 https://mypy-play.net/?mypy=0.760&python=3.8&gist=b605afaed49a278a76deed5fbc7f8439

mypy started accepting these (hit the burger in the top right -> press run to run mypy)

1reaction

thejohnfreemancommented, May 13, 2020

That could be possible. I tried revisiting this issue over the weekend and wasn’t able to reproduce it any more. To be honest, I’m prepared to just let it go. If I figure out how to reproduce it again (by accident because I won’t be dedicating any deliberate effort), then I’ll re-open this issue. Thanks for taking a look.