$ make
cython msgpack/_cmsgpack.pyx
python setup.py build_ext -i -f
running build_ext
building 'msgpack._cmsgpack' extension
creating build
creating build/temp.linux-x86_64-cpython-314
creating build/temp.linux-x86_64-cpython-314/msgpack
x86_64-linux-gnu-gcc -fno-strict-overflow -Wsign-compare -DNDEBUG -g -O2 -Wall -g -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -flto=auto -ffat-lto-objects -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -fPIC -I. -I/tmp/venv/include -I/usr/include/python3.14t -c msgpack/_cmsgpack.c -o build/temp.linux-x86_64-cpython-314/msgpack/_cmsgpack.o
msgpack/_cmsgpack.c:2343:80: error: unknown type name ‘__pyx_vectorcallfunc’; did you mean ‘vectorcallfunc’?
 2343 | ject *__Pyx_PyVectorcall_FastCallDict(PyObject *func, __pyx_vectorcallfunc vc, PyObject *const *args, size_t nargs, PyObject *kw);
      |                                                       ^~~~~~~~~~~~~~~~~~~~
      |                                                       vectorcallfunc
msgpack/_cmsgpack.c: In function ‘__pyx_pf_7msgpack_9_cmsgpack_6Packer_2__dealloc__’:
msgpack/_cmsgpack.c:6941:3: warning: ‘Py_OptimizeFlag’ is deprecated [-Wdeprecated-declarations]
 6941 |   if (unlikely(__pyx_assertions_enabled())) {
      |   ^~
In file included from /usr/include/python3.14t/Python.h:72,
                 from msgpack/_cmsgpack.c:16:
/usr/include/python3.14t/cpython/pydebug.h:13:37: note: declared here
   13 | Py_DEPRECATED(3.12) PyAPI_DATA(int) Py_OptimizeFlag;
      |                                     ^~~~~~~~~~~~~~~
msgpack/_cmsgpack.c: At top level:
msgpack/_cmsgpack.c:21382:69: error: unknown type name ‘__pyx_vectorcallfunc’; did you mean ‘vectorcallfunc’?
21382 | t *__Pyx_PyVectorcall_FastCallDict_kw(PyObject *func, __pyx_vectorcallfunc vc, PyObject *const *args, size_t nargs, PyObject *kw)
      |                                                       ^~~~~~~~~~~~~~~~~~~~
      |                                                       vectorcallfunc
msgpack/_cmsgpack.c:21427:80: error: unknown type name ‘__pyx_vectorcallfunc’; did you mean ‘vectorcallfunc’?
21427 | ject *__Pyx_PyVectorcall_FastCallDict(PyObject *func, __pyx_vectorcallfunc vc, PyObject *const *args, size_t nargs, PyObject *kw)
      |                                                       ^~~~~~~~~~~~~~~~~~~~
      |                                                       vectorcallfunc
msgpack/_cmsgpack.c: In function ‘__Pyx_CyFunction_CallAsMethod’:
msgpack/_cmsgpack.c:22116:6: error: unknown type name ‘__pyx_vectorcallfunc’; did you mean ‘vectorcallfunc’?
22116 |      __pyx_vectorcallfunc vc = __Pyx_CyFunction_func_vectorcall(cyfunc);
      |      ^~~~~~~~~~~~~~~~~~~~
      |      vectorcallfunc
msgpack/_cmsgpack.c:2433:45: warning: initialization of ‘int’ from ‘vectorcallfunc’ {aka ‘struct _object * (*)(struct _object *, struct _object * const*, long unsigned int,  struct _object *)’} makes integer from pointer without a cast [-Wint-conversion]
 2433 | #define __Pyx_CyFunction_func_vectorcall(f) (((PyCFunctionObject*)f)->vectorcall)
      |                                             ^
msgpack/_cmsgpack.c:22116:32: note: in expansion of macro ‘__Pyx_CyFunction_func_vectorcall’
22116 |      __pyx_vectorcallfunc vc = __Pyx_CyFunction_func_vectorcall(cyfunc);
      |                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
msgpack/_cmsgpack.c:22119:16: warning: implicit declaration of function ‘__Pyx_PyVectorcall_FastCallDict’; did you mean ‘__Pyx_PyObject_FastCallDict’? [-Wimplicit-function-declaration]
22119 |         return __Pyx_PyVectorcall_FastCallDict(func, vc, &PyTuple_GET_ITEM(args, 0), (size_t)PyTuple_GET_SIZE(args), kw);
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                __Pyx_PyObject_FastCallDict
msgpack/_cmsgpack.c:22119:16: warning: returning ‘int’ from a function with return type ‘PyObject *’ {aka ‘struct _object *’} makes pointer from integer without a cast [-Wint-conversion]
22119 |         return __Pyx_PyVectorcall_FastCallDict(func, vc, &PyTuple_GET_ITEM(args, 0), (size_t)PyTuple_GET_SIZE(args), kw);
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
error: command '/usr/bin/x86_64-linux-gnu-gcc' failed with exit code 1
make: *** [Makefile:5: all] Error 1