Description of problem:

When trying to address the bugzilla report that lhapdf is not buildable with Python 3.12, I encountered that Cython generates code that uses Python C API functions that have been removed in Python 3.12:

/builddir/build/BUILD/LHAPDF-6.5.3/wrappers/python/lhapdf.cpp: In function ‘int __Pyx_PyUnicode_Equals(PyObject*, PyObject*, int)’:
/builddir/build/BUILD/LHAPDF-6.5.3/wrappers/python/lhapdf.cpp:571:51: error: ‘_PyUnicode_Ready’ was not declared in this scope; did you mean ‘PyUnicode_READY’?
  571 |                                               0 : _PyUnicode_Ready((PyObject *)(op)))
      |                                                   ^~~~~~~~~~~~~~~~
/builddir/build/BUILD/LHAPDF-6.5.3/wrappers/python/lhapdf.cpp:977:43: note: in definition of macro ‘unlikely’
  977 |   #define unlikely(x) __builtin_expect(!!(x), 0)
      |                                           ^
/builddir/build/BUILD/LHAPDF-6.5.3/wrappers/python/lhapdf.cpp:26280:22: note: in expansion of macro ‘__Pyx_PyUnicode_READY’
26280 |         if (unlikely(__Pyx_PyUnicode_READY(s1) < 0) || unlikely(__Pyx_PyUnicode_READY(s2) < 0))
      |                      ^~~~~~~~~~~~~~~~~~~~~
/builddir/build/BUILD/LHAPDF-6.5.3/wrappers/python/lhapdf.cpp: In function ‘const char* __Pyx_PyUnicode_AsStringAndSize(PyObject*, Py_ssize_t*)’:
/builddir/build/BUILD/LHAPDF-6.5.3/wrappers/python/lhapdf.cpp:571:51: error: ‘_PyUnicode_Ready’ was not declared in this scope; did you mean ‘PyUnicode_READY’?
  571 |                                               0 : _PyUnicode_Ready((PyObject *)(op)))
      |                                                   ^~~~~~~~~~~~~~~~
/builddir/build/BUILD/LHAPDF-6.5.3/wrappers/python/lhapdf.cpp:977:43: note: in definition of macro ‘unlikely’
  977 |   #define unlikely(x) __builtin_expect(!!(x), 0)
      |                                           ^
/builddir/build/BUILD/LHAPDF-6.5.3/wrappers/python/lhapdf.cpp:29016:18: note: in expansion of macro ‘__Pyx_PyUnicode_READY’
29016 |     if (unlikely(__Pyx_PyUnicode_READY(o) == -1)) return NULL;
      |                  ^~~~~~~~~~~~~~~~~~~~~


Version-Release number of selected component (if applicable):

DEBUG util.py:445:   python3-Cython                  x86_64 0.29.32-1.fc38     \
     python312 2.5 M


How reproducible:

Always


Actual results:

Generated code calls functions removed in Python 3.12


Expected results:

Generated code compiles with Python 3.12


Additional info:

Possibly fixed upstream by this commit:

https://github.com/cython/cython/commit/b4595a04a78b79dc59276a9f64aab7b884e945e8