I've tried to report this on sip mailing list, but I don't know if the message reached it because I can't see it on mailing list archive.

python-wxpython4 fails to build with Python 3.12.0a7.

../../../../sip/cpp/sip_corewxArrayString.cpp: In function ‘int convertTo_wxArrayString(PyObject*, void**, int*, PyObject*)’:
../../../../sip/cpp/sip_corewxArrayString.cpp:91:26: error: ‘PyUnicode_GET_SIZE’ was not declared in this scope; did you mean ‘PyDict_GET_SIZE’?
   91 |             size_t len = PyUnicode_GET_SIZE(item);
      |                          ^~~~~~~~~~~~~~~~~~
      |                          PyDict_GET_SIZE

This happens because of a change in CPython, where PyUnicode_GET_SIZE() was removed.

From what's new:
    Legacy Unicode APIs have been removed. See PEP 623 for detail.
            PyUnicode_WCHAR_KIND
            PyUnicode_AS_UNICODE()
            PyUnicode_AsUnicode()
            PyUnicode_AsUnicodeAndSize()
            PyUnicode_AS_DATA()
            PyUnicode_FromUnicode()
            PyUnicode_GET_SIZE()
            PyUnicode_GetSize()
            PyUnicode_GET_DATA_SIZE()

https://docs.python.org/3.12/whatsnew/3.12.html

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.12/fedora-rawhide-x86_64/05903515-python-wxpython4/

For all our attempts to build python-wxpython4 with Python 3.12, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.12/package/python-wxpython4/

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 3.12:
https://copr.fedorainfracloud.org/coprs/g/python/python3.12/

Let us know here if you have any questions.

Python 3.12 is planned to be included in Fedora 39. To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.12.
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.