Protobuf Python extension module is not ABI compatible with Stackless Python

[akruis]

What version of protobuf and what language are you using?
Version: any version, that uses the CPP extension module i.e. 3.7.1
Language: Stackless Python

What operating system (Linux, Windows, ...) and version?
Not relevant

What runtime / compiler are you using (e.g., python version or gcc version)
Not relevant

What did you do?
Steps to reproduce the behavior:

1. Install Stackless Python 3.7.3
2. install protobuf 3.7.1 wheel
   $ python -m pip install protobuf
3. run the following python code (minimal example)

   from google.protobuf.pyext import _message
   def func():
       _message.Message._CheckCalledFromGeneratedFile()
   func()
   

What did you expect to see

TypeError: Descriptors should not be created directly, but only retrieved from their parent.

What did you see instead?

Segmentation fault (core dumped)

Anything else we should know about your project / environment

The segmentation fault is caused by the following line of code:

protobuf/python/google/protobuf/pyext/descriptor.cc

Line 114 in 6973c3a

if (frame->f_code->co_filename == NULL) {

The problem is, that protobuf uses the structure PyFrameObject (frame->f_code) which is not part of the C-Python ABI and differs between C-Python and Stackless Python. See https://github.com/stackless-dev/stackless/wiki/Portable-usage-of-PyFrameObject for details.

Merging pull request #5171 would fix the problem.

Another option is compute the offset of the field f_code at runtime. Use the macro PYFRAME_CODE(frame) from https://github.com/stackless-dev/stackless/wiki/Portable-usage-of-PyFrameObject.

Work arounds

1. Install the pure Python version of protobuf or
2. Compile protobuf using Stackless Python

[anandolee]

I think #5171 owner may not working on the PR anymore. I will remove _CheckCalledFromGeneratedFile() in another change later.

[snoopy-coder]

I recently encountered an error while using Protobuf Python extension module.
tdryer/hangups#451 (comment)
Not sure it is relevant to this discussion, but I consider it necessary to inform you.

[haberman]

Closing as obsolete. The relevant APIs (eg. _CheckCalledFromGeneratedFile) have been removed.