cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration wctype/iswctype_l.c -o wctype/iswctype_l -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
wctype/iswctype_l.c:13:23: error: call to undeclared function 'wctype_l'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   13 |         wctype_t charclass = wctype_l("alpha", locale);
      |                              ^
wctype/iswctype_l.c:13:23: note: did you mean 'wctype'?
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/___wctype.h:190:2: note: 'wctype' declared here
  190 |         wctype(const char *);
      |         ^
wctype/iswctype_l.c:18:8: error: call to undeclared function 'iswctype_l'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   18 |         if ( !iswctype_l(wc1, charclass, locale) )
      |               ^
2 errors generated.