cc -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations signal/sigqueue.c -o signal/sigqueue -D_POSIX_C_SOURCE=202405L -lm -lpthread -lrt -lintl -liconv
signal/sigqueue.c:5:40: error: ‘sigqueue’ undeclared here (not in a function)
    5 | int (*foo)(pid_t, int, union sigval) = sigqueue;
      |                                        ^~~~~~~~