Build fails on CPython alphas ("3.10")

[Rosuav]

• gevent version: master branch (currently ed26336)
• Python version: CPython 3.10 alpha built from git, revision 9645930b5b (master branch as of time of building)
• Operating System: Debian Linux 9.12 (Stretch) Linux 4.9.0-11-amd6

Description:

gevent fails to build on the current alphas, but worked (with workarounds) on the later alphas and betas of 3.9.

What I've run:

Build CPython from source, install, etc. Create a fresh venv and attempt to install gevent:

$ python3.10 -m venv env
$ source env/bin/activate
$ pip install -U pip
$ pip install cython # optional, doesn't fix anything
$ pip install -v git+git://github.com/gevent/gevent.git

The build fails with this message:

      gcc -pthread -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -fPIC -I/home/rosuav/asdf/env/include -I/usr/local/include/python3.10 -c greenlet.c -o build/temp.linux-x86_64-3.10/greenlet.o
      greenlet.c: In function ‘g_initialstub’:
      greenlet.c:823:4: warning: ‘PyEval_CallObjectWithKeywords’ is deprecated [-Wdeprecated-declarations]
          result = PyEval_CallObjectWithKeywords(
          ^~~~~~
      In file included from /usr/local/include/python3.10/Python.h:145:0,
                       from greenlet.h:8,
                       from greenlet.c:5:
      /usr/local/include/python3.10/ceval.h:17:43: note: declared here
       Py_DEPRECATED(3.9) PyAPI_FUNC(PyObject *) PyEval_CallObjectWithKeywords(
                                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      greenlet.c: In function ‘green_dealloc’:
      greenlet.c:1046:4: error: ‘_Py_DEC_REFTOTAL’ undeclared (first use in this function)
          _Py_DEC_REFTOTAL;
          ^~~~~~~~~~~~~~~~
      greenlet.c:1046:4: note: each undeclared identifier is reported only once for each function it appears in
      error: command '/usr/bin/gcc' failed with exit code 1

Unsure whether the problem is in gevent or in cython. Not sure how to track down the distinction.

[jamadden]

Thanks for the report.

These errors belong to greenlet, the underlying green-threads library.

For 3.9, @vstinner submitted patches to greenlet to account for the breaking API changes. I think perhaps those are the same API changes you're seeing here, they just haven't been released yet.

[Rosuav]

Ah, cool. Thanks. I'll check back later on; for now, I just have to run things in 3.9.

[vstinner]

For 3.9, @vstinner submitted patches to greenlet to account for the breaking API changes.

There is no release including my fix: the latest one was done 2 years ago, https://pypi.org/project/greenlet/#history