cc -O2 -pipe -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations signal/sig2str.c -o signal/sig2str -D_POSIX_C_SOURCE=202405L  -lm -lpthread -lrt  -lstdthreads -lcrypt
signal/sig2str.c:5:27: error: use of undeclared identifier 'sig2str'
    5 | int (*foo)(int, char *) = sig2str;
      |                           ^
1 error generated.