cc -O2 -pipe  -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations time/timer_delete.c -o time/timer_delete -D_POSIX_C_SOURCE=202405L  -lm -lpthread 
time/timer_delete.c:5:23: error: use of undeclared identifier 'timer_delete'
int (*foo)(timer_t) = timer_delete;
                      ^
1 error generated.