cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration wctype/towctrans_l.c -o wctype/towctrans_l -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
wctype/towctrans_l.c:13:19: error: call to undeclared function 'wctrans_l'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   13 |         wctrans_t desc = wctrans_l("tolower", locale);
      |                          ^
wctype/towctrans_l.c:13:19: note: did you mean 'wctrans'?
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_wctype.h:126:2: note: 'wctrans' declared here
  126 |         wctrans(const char *);
      |         ^
wctype/towctrans_l.c:18:16: error: call to undeclared function 'towctrans_l'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   18 |         wchar_t wc3 = towctrans_l(wc1, desc, locale);
      |                       ^
2 errors generated.