Compilation breaks on Python 3.11.0a7 in PyFrame_GetLasti

[icemac]

Using the latest version of pythoncapi_compat.h currently breaks on Python 3.11.0a7.
I have seen this on GHA for Ubuntu and MacOS and locally on MacOS:

src/zope/container/_compat.h:254:14: error: incomplete definition of type 'struct _frame'
    if (frame->f_lasti < 0) {
        ~~~~~^
/Users/runner/hostedtoolcache/Python/3.11.0-alpha.7/x64/include/python3.11/pytypedefs.h:22:16: note: forward declaration of 'struct _frame'
typedef struct _frame PyFrameObject;
               ^
In file included from src/zope/container/_zope_container_contained.c:34:
src/zope/container/_compat.h:257:17: error: incomplete definition of type 'struct _frame'
    return frame->f_lasti * 2;
           ~~~~~^

See https://github.com/zopefoundation/zope.container/runs/6188321544?check_suite_focus=true#step:7:61 where pythoncapi_compat.h is src/zope/container/_compat.h.

[vstinner]

If you don't need the latest enhancements of pythoncapi_compat.h, just keep your old version.

Sadly, the new version is not compatible with Python 3.11 alpha versions. PyFrameObject got a lot of changes in alpha versions. Hopefully, new public getter functions were added to solve most issues: https://docs.python.org/dev/c-api/frame.html Problem: implementing these getter functions for early alpha versions would require a lot of code in pythoncapi_compat.h, and I chose to not do that.

Workaround if you need to update pythoncapi_compat.h: manually remove the PyFrame functions which cause you build errors. Does it sound like a reasonable workaround to you? That's the approach that I adopted in my coverage PR: nedbat/coveragepy#1353

[vstinner]

(Oops, I clicked on the wrong button by mistake, I didn't want to close the issue.)

[icemac]

@vstinner Thank you for your explanation. It seems that I do not need PyFrame_GetLasti – at least in zope.container.

Thank you for your hard work on the compatibility side!

[vstinner]

Python 3.11 beta3 is now released: can you update to a newer Python 3.11?

[icemac]

I am trying to do so in zopefoundation/zope.container#45, but there are several other problems which arose over night in Python 3.10 and need to be fixed beforehand.

[vstinner]

It seems to be unrelated to pythoncapi-compat. I close the issue.

Supporting alpha versions of Python 3.11 is too complicated. To get Python 3.11, use beta1 or newer.