cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration wchar/wcscoll_l.c -o wchar/wcscoll_l -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
wchar/wcscoll_l.c:15:19: error: call to undeclared function 'wcscoll_l'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   15 |         int comparison = wcscoll_l(a, b, locale);
      |                          ^
wchar/wcscoll_l.c:15:19: note: did you mean 'wcscoll'?
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_wchar.h:133:5: note: 'wcscoll' declared here
  133 | int     wcscoll(const wchar_t *, const wchar_t *);
      |         ^
1 error generated.