clang -O2  -Wall -Wextra -Werror=implicit-function-declaration signal/sig2str.c -o signal/sig2str -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm  -lintl
signal/sig2str.c:9:12: error: use of undeclared identifier 'SIG2STR_MAX'
        char name[SIG2STR_MAX];
                  ^
signal/sig2str.c:10:7: error: implicit declaration of function 'sig2str' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        if ( sig2str(SIGUSR1, name) < 0 )
             ^
2 errors generated.