cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration wchar/fwprintf.c -o wchar/fwprintf -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lintl -liconv
wchar/fwprintf.c: In function ‘main’:
wchar/fwprintf.c:12:14: error: implicit declaration of function ‘fwprintf’; did you mean ‘fprintf’? [-Wimplicit-function-declaration]
   12 |         if ( fwprintf(fp, L"hello %ls %d", L"world", 42) < 0 )
      |              ^~~~~~~~
      |              fprintf
wchar/fwprintf.c:19:15: error: implicit declaration of function ‘fgetws’; did you mean ‘fgets’? [-Wimplicit-function-declaration]
   19 |         if ( !fgetws(buf, sizeof(buf)/sizeof(buf[0]), fp) )
      |               ^~~~~~
      |               fgets