cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration wchar/fwide.c -o wchar/fwide -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lintl -liconv
wchar/fwide.c: In function ‘main’:
wchar/fwide.c:9:14: error: implicit declaration of function ‘fwide’ [-Wimplicit-function-declaration]
    9 |         if ( fwide(stdin, 0) != 0 )
      |              ^~~~~
wchar/fwide.c:34:14: error: implicit declaration of function ‘fputwc’; did you mean ‘fputc’? [-Wimplicit-function-declaration]
   34 |         if ( fputwc(L'x', fp3) == WEOF )
      |              ^~~~~~
      |              fputc
wchar/fwide.c:34:32: warning: comparison of integer expressions of different signedness: ‘int’ and ‘unsigned int’ [-Wsign-compare]
   34 |         if ( fputwc(L'x', fp3) == WEOF )
      |                                ^~
wchar/fwide.c:39:14: error: implicit declaration of function ‘fgetwc’; did you mean ‘fgetc’? [-Wimplicit-function-declaration]
   39 |         if ( fgetwc(fp4) != WEOF )
      |              ^~~~~~
      |              fgetc
wchar/fwide.c:39:26: warning: comparison of integer expressions of different signedness: ‘int’ and ‘unsigned int’ [-Wsign-compare]
   39 |         if ( fgetwc(fp4) != WEOF )
      |                          ^~