cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration wchar/wcsxfrm_l.c -o wchar/wcsxfrm_l -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
wchar/wcsxfrm_l.c:17:7: error: call to undeclared function 'wcsxfrm_l'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   17 |         if ( wcsxfrm_l(A, a, sizeof(A) / sizeof(A[0]), locale) != 7 )
      |              ^
wchar/wcsxfrm_l.c:17:7: note: did you mean 'wcsxfrm'?
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_wchar.h:157:8: note: 'wcsxfrm' declared here
  157 | size_t  wcsxfrm(wchar_t * __restrict _LIBC_COUNT(__n),
      |         ^
wchar/wcsxfrm_l.c:22:13: error: call to undeclared function 'wcscoll_l'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   22 |         int coll = wcscoll_l(a, b, locale);
      |                    ^
wchar/wcsxfrm_l.c:22:13: 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 *);
      |         ^
2 errors generated.