clang -O2  -Wall -Wextra -Werror=implicit-function-declaration wchar/wcpncpy.c -o wchar/wcpncpy -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm  -lintl
wchar/wcpncpy.c:7:32: warning: unknown warning group '-Wstringop-truncation', ignored [-Wunknown-pragmas]
#pragma GCC diagnostic ignored "-Wstringop-truncation"
                               ^
wchar/wcpncpy.c:13:7: error: implicit declaration of function 'wcpncpy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        if ( wcpncpy(dst, src, 4) != dst + 4 )
             ^
wchar/wcpncpy.c:13:7: note: did you mean 'wcsncpy'?
/usr/include/wchar.h:118:10: note: 'wcsncpy' declared here
wchar_t *wcsncpy(wchar_t * __restrict , const wchar_t * __restrict, size_t);
         ^
wchar/wcpncpy.c:13:28: warning: comparison between pointer and integer ('int' and 'wchar_t *' (aka 'int *'))
        if ( wcpncpy(dst, src, 4) != dst + 4 )
             ~~~~~~~~~~~~~~~~~~~~ ^  ~~~~~~~
2 warnings and 1 error generated.