Seems PR 11328 introduced a compiler warning:
In file included from ./Include/Python.h:64:0,
from ./Python/sysmodule.c:17:
./Python/sysmodule.c:1597:14: warning: ‘sys_clear_type_cache__doc__’ defined but not used [-Wunused-variable]
PyDoc_STRVAR(sys_clear_type_cache__doc__,
^
./Include/pymacro.h:70:37: note: in definition of macro ‘PyDoc_VAR’
#define PyDoc_VAR(name) static char name[]
^~~~
./Python/sysmodule.c:1597:1: note: in expansion of macro ‘PyDoc_STRVAR’
PyDoc_STRVAR(sys_clear_type_cache__doc__,
^~~~~~~~~~~~