python-zstd fails to build with Python 3.11.0a2.

src/python-zstd.c:119:25: error: lvalue required as left operand of assignment
  119 |         Py_SIZE(result) = cSize;
      |                         ^
src/python-zstd.c: At top level:
src/python-zstd.c:212:9: note: ‘#pragma message: Old style functions are deprecated since 2018-05-06 and may be removed any time!’
  212 | #pragma message "Old style functions are deprecated since 2018-05-06 and may be removed any time!"
      |         ^~~~~~~
src/python-zstd.c: In function ‘py_zstd_compress_old’:
src/python-zstd.c:283:29: error: lvalue required as left operand of assignment
  283 |             Py_SIZE(result) = cSize + hdr_size;

Since Py_SIZE() is changed to a inline static function, Py_SIZE(obj) = new_size must be replaced with Py_SET_SIZE(obj, new_size): see the Py_SET_SIZE() function (available since Python 3.9). For backward compatibility, this macro can be used:

#if PY_VERSION_HEX < 0x030900A4 && !defined(Py_SET_SIZE)
static inline void _Py_SET_SIZE(PyVarObject *ob, Py_ssize_t size)
{ ob->ob_size = size; }
#define Py_SET_SIZE(ob, size) _Py_SET_SIZE((PyVarObject*)(ob), size)
#endif

(Contributed by Victor Stinner in bpo-39573.)

https://bugs.python.org/issue39573
https://docs.python.org/3.11/whatsnew/3.11.html

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.11/fedora-rawhide-x86_64/02940972-python-zstd/

For all our attempts to build python-zstd with Python 3.11, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.11/package/python-zstd/

Testing and mass rebuild of packages is happening in copr. You can follow these instructions to test locally in mock if your package builds with Python 3.11:
https://copr.fedorainfracloud.org/coprs/g/python/python3.11/

Let us know here if you have any questions.

Python 3.11 is planned to be included in Fedora 37. To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.11.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires), so if this package is required a lot, it's important for us to get it fixed soon.
We'd appreciate help from the people who know this package best, but if you don't want to work on this now, let us know so we can try to work around it on our side.