Build fails on Python 3.10 nightly

[akaihola]

I'm seeing these errors when building on Python 3.10 nightly on Travis CI:

    gcc -pthread -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -g -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security -fPIC -D__RTMIDI_SILENCE_WARNINGS__ -D__LINUX_ALSA__ -D__UNIX_JACK__ -Isrc/rtmidi -I/home/travis/virtualenv/python3.10-dev/include -I/opt/python/3.10-dev/include/python3.10 -c src/_rtmidi.cpp -o build/temp.linux-x86_64-3.10/src/_rtmidi.o
    src/_rtmidi.cpp: In function ‘int __Pyx_ListComp_Append(PyObject*, PyObject*)’:
    src/_rtmidi.cpp:1071:23: error: lvalue required as left operand of assignment
             Py_SIZE(list) = len+1;
                           ^
    In file included from /opt/python/3.10-dev/include/python3.10/pytime.h:6:0,
                     from /opt/python/3.10-dev/include/python3.10/Python.h:85,
                     from src/_rtmidi.cpp:47:
    src/_rtmidi.cpp: In function ‘void __pyx_tp_dealloc_6rtmidi_7_rtmidi_MidiIn(PyObject*)’:
    /opt/python/3.10-dev/include/python3.10/object.h:128:58: error: lvalue required as increment operand
     #define Py_REFCNT(ob) _Py_REFCNT(_PyObject_CAST_CONST(ob))
                                                              ^
    src/_rtmidi.cpp:10464:7: note: in expansion of macro ‘Py_REFCNT’
         ++Py_REFCNT(o);
           ^
    /opt/python/3.10-dev/include/python3.10/object.h:128:58: error: lvalue required as decrement operand
     #define Py_REFCNT(ob) _Py_REFCNT(_PyObject_CAST_CONST(ob))
                                                              ^
    src/_rtmidi.cpp:10466:7: note: in expansion of macro ‘Py_REFCNT’
         --Py_REFCNT(o);
           ^
    src/_rtmidi.cpp: In function ‘void __pyx_tp_dealloc_6rtmidi_7_rtmidi_MidiOut(PyObject*)’:
    /opt/python/3.10-dev/include/python3.10/object.h:128:58: error: lvalue required as increment operand
     #define Py_REFCNT(ob) _Py_REFCNT(_PyObject_CAST_CONST(ob))
                                                              ^
    src/_rtmidi.cpp:10609:7: note: in expansion of macro ‘Py_REFCNT’
         ++Py_REFCNT(o);
           ^
    /opt/python/3.10-dev/include/python3.10/object.h:128:58: error: lvalue required as decrement operand
     #define Py_REFCNT(ob) _Py_REFCNT(_PyObject_CAST_CONST(ob))
                                                              ^
    src/_rtmidi.cpp:10611:7: note: in expansion of macro ‘Py_REFCNT’
         --Py_REFCNT(o);
           ^

immutables seems to have the same issue, see immutables#46 for discussion and proposed solutions.

[SpotlightKid]

Have you tried recreating src/_rtmidi.cpp with Cython? Are you using the latest Cython version?

[akaihola]

Thanks @SpotlightKid, that fixed it, here's my build on Travis CI!

[DestyNova]

@SpotlightKid are there instructions on how to do that? I tried installing with pip install but got the same error.

[edit] Oh, fixed it, my mistake.