cc -pthread  -Wall -Wextra freelocale.c -o freelocale -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
freelocale.c:9:2: error: use of undeclared identifier 'locale_t'
        locale_t locale = newlocale(LC_ALL_MASK, "C", (locale_t) 0);
        ^
freelocale.c:10:18: error: use of undeclared identifier 'locale_t'
        if ( locale == (locale_t) 0 )
                        ^
freelocale.c:10:7: error: use of undeclared identifier 'locale'
        if ( locale == (locale_t) 0 )
             ^
freelocale.c:12:2: error: implicit declaration of function 'freelocale' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        freelocale(locale);
        ^
freelocale.c:12:2: note: did you mean 'setlocale'?
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/locale.h:53:8: note: 'setlocale' declared here
char            *setlocale(int, const char *);
                 ^
freelocale.c:12:13: error: use of undeclared identifier 'locale'
        freelocale(locale);
                   ^
5 errors generated.