libkdtree++ fails to build with Python 3.11.0b1.

In file included from /usr/include/python3.11/Python.h:38,
                 from py-kdtree_wrap.cxx:178:
/usr/include/python3.11/pyport.h:39:20: warning: identifier 'nullptr' is a keyword in C++11 [-Wc++11-compat]
   39 | #  define _Py_NULL nullptr
      |                    ^~~~~~~
/usr/include/python3.11/object.h:590:15: note: in expansion of macro '_Py_NULL'
  590 |     if (op != _Py_NULL) {
      |               ^~~~~~~~
In file included from /usr/include/python3.11/pymem.h:96,
                 from /usr/include/python3.11/Python.h:41:
/usr/include/python3.11/cpython/pymem.h:42:39: warning: comma at end of enumerator list [-Wpedantic]
   42 |     PYMEM_ALLOCATOR_PYMALLOC_DEBUG = 6,
      |                                       ^
/usr/include/python3.11/object.h: In function 'void Py_XINCREF(PyObject*)':
/usr/include/python3.11/pyport.h:39:20: error: 'nullptr' was not declared in this scope
   39 | #  define _Py_NULL nullptr
      |                    ^~~~~~~
/usr/include/python3.11/object.h:590:15: note: in expansion of macro '_Py_NULL'
  590 |     if (op != _Py_NULL) {
      |               ^~~~~~~~
/usr/include/python3.11/object.h: In function 'void Py_XDECREF(PyObject*)':
/usr/include/python3.11/pyport.h:39:20: error: 'nullptr' was not declared in this scope
   39 | #  define _Py_NULL nullptr
      |                    ^~~~~~~
/usr/include/python3.11/object.h:600:15: note: in expansion of macro '_Py_NULL'
  600 |     if (op != _Py_NULL) {
      |               ^~~~~~~~
In file included from /usr/include/python3.11/Python.h:44:
/usr/include/python3.11/object.h: At global scope:
/usr/include/python3.11/object.h:678:19: warning: comma at end of enumerator list [-Wpedantic]
  678 |     PYGEN_NEXT = 1,
      |                   ^
/usr/include/python3.11/cpython/unicodeobject.h: In function 'Py_ssize_t PyUnicode_GET_SIZE(PyObject*)':
/usr/include/python3.11/pyport.h:39:20: error: 'nullptr' was not declared in this scope
   39 | #  define _Py_NULL nullptr
      |                    ^~~~~~~
/usr/include/python3.11/cpython/unicodeobject.h:645:42: note: in expansion of macro '_Py_NULL'
  645 |     if (_PyASCIIObject_CAST(op)->wstr == _Py_NULL) {
      |                                          ^~~~~~~~
/usr/include/python3.11/cpython/unicodeobject.h: In function 'Py_UNICODE* PyUnicode_AS_UNICODE(PyObject*)':
/usr/include/python3.11/pyport.h:39:20: error: 'nullptr' was not declared in this scope
   39 | #  define _Py_NULL nullptr
      |                    ^~~~~~~
/usr/include/python3.11/cpython/unicodeobject.h:677:17: note: in expansion of macro '_Py_NULL'
  677 |     if (wstr != _Py_NULL) {
      |                 ^~~~~~~~
/usr/include/python3.11/cpython/methodobject.h: In function 'PyObject* PyCFunction_GET_SELF(PyObject*)':
/usr/include/python3.11/pyport.h:39:20: error: 'nullptr' was not declared in this scope
   39 | #  define _Py_NULL nullptr
      |                    ^~~~~~~
/usr/include/python3.11/cpython/methodobject.h:50:16: note: in expansion of macro '_Py_NULL'
   50 |         return _Py_NULL;
      |                ^~~~~~~~
/usr/include/python3.11/cpython/methodobject.h: In function 'PyTypeObject* PyCFunction_GET_CLASS(PyObject*)':
/usr/include/python3.11/pyport.h:39:20: error: 'nullptr' was not declared in this scope
   39 | #  define _Py_NULL nullptr
      |                    ^~~~~~~
/usr/include/python3.11/cpython/methodobject.h:70:12: note: in expansion of macro '_Py_NULL'
   70 |     return _Py_NULL;
      |            ^~~~~~~~
/usr/include/python3.11/cpython/abstract.h: In function 'PyObject* PyObject_CallMethodNoArgs(PyObject*, PyObject*)':
/usr/include/python3.11/pyport.h:39:20: error: 'nullptr' was not declared in this scope
   39 | #  define _Py_NULL nullptr
      |                    ^~~~~~~
/usr/include/python3.11/cpython/abstract.h:107:59: note: in expansion of macro '_Py_NULL'
  107 |     return PyObject_VectorcallMethod(name, &self, nargsf, _Py_NULL);
      |                                                           ^~~~~~~~
/usr/include/python3.11/cpython/abstract.h: In function 'PyObject* PyObject_CallMethodOneArg(PyObject*, PyObject*, PyObject*)':
/usr/include/python3.11/pyport.h:39:20: error: 'nullptr' was not declared in this scope
   39 | #  define _Py_NULL nullptr
      |                    ^~~~~~~
/usr/include/python3.11/cpython/abstract.h:117:58: note: in expansion of macro '_Py_NULL'
  117 |     return PyObject_VectorcallMethod(name, args, nargsf, _Py_NULL);
      |                                                          ^~~~~~~~
/usr/include/python3.11/cpython/abstract.h: In function 'PyObject* _PyObject_VectorcallMethodId(_Py_Identifier*, PyObject* const*, size_t, PyObject*)':
/usr/include/python3.11/pyport.h:39:20: error: 'nullptr' was not declared in this scope
   39 | #  define _Py_NULL nullptr
      |                    ^~~~~~~
/usr/include/python3.11/cpython/abstract.h:147:16: note: in expansion of macro '_Py_NULL'
  147 |         return _Py_NULL;
      |                ^~~~~~~~
/usr/include/python3.11/cpython/abstract.h: In function 'PyObject* _PyObject_CallMethodIdNoArgs(PyObject*, _Py_Identifier*)':
/usr/include/python3.11/pyport.h:39:20: error: 'nullptr' was not declared in this scope
   39 | #  define _Py_NULL nullptr
      |                    ^~~~~~~
/usr/include/python3.11/cpython/abstract.h:156:62: note: in expansion of macro '_Py_NULL'
  156 |     return _PyObject_VectorcallMethodId(name, &self, nargsf, _Py_NULL);
      |                                                              ^~~~~~~~
/usr/include/python3.11/cpython/abstract.h: In function 'PyObject* _PyObject_CallMethodIdOneArg(PyObject*, _Py_Identifier*, PyObject*)':
/usr/include/python3.11/pyport.h:39:20: error: 'nullptr' was not declared in this scope
   39 | #  define _Py_NULL nullptr
      |                    ^~~~~~~
/usr/include/python3.11/cpython/abstract.h:166:61: note: in expansion of macro '_Py_NULL'
  166 |     return _PyObject_VectorcallMethodId(name, args, nargsf, _Py_NULL);
      |                                                             ^~~~~~~~
py-kdtree_wrap.cxx: In function 'PyObject* PyInit__kdtree()':
/usr/include/python3.11/pyport.h:39:20: error: 'nullptr' was not declared in this scope
   39 | #  define _Py_NULL nullptr
      |                    ^~~~~~~
/usr/include/python3.11/object.h:81:8: note: in definition of macro 'PyObject_HEAD_INIT'
   81 |     1, type },
      |        ^~~~
/usr/include/python3.11/moduleobject.h:52:24: note: in expansion of macro '_Py_NULL'
   52 |     PyObject_HEAD_INIT(_Py_NULL) \
      |                        ^~~~~~~~
py-kdtree_wrap.cxx:6535:5: note: in expansion of macro 'PyModuleDef_HEAD_INIT'
 6535 |     PyModuleDef_HEAD_INIT,
      |     ^~~~~~~~~~~~~~~~~~~~~
make: *** [Makefile:35: _kdtree.so] Error 1

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_64/04392263-libkdtree++/

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

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.