https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91092
--- Comment #2 from Florian Weimer <fw at gcc dot gnu.org> ---
Current util-linux is an example:
$ ./configure
[…]
checking wchar_t support... yes
[…]
$ ./configure CC="gcc -Werror=implicit-function-declaration"
[…]
configure: WARNING: wchar_t support not found; not building widechar
[…]
configure.ac has this:
AC_ARG_ENABLE([widechar],
AS_HELP_STRING([--disable-widechar], [do not compile wide character
support]),
[], [enable_widechar=check]
)
UL_BUILD_INIT([widechar])
UL_REQUIRES_COMPILE([widechar], [[
#include <wchar.h>
#include <wctype.h>
#include <stdio.h>
]], [[
wchar_t wc;
wint_t w;
w = fgetwc(stdin);
if (w == WEOF) exit(1);
wc = w;
fputwc(wc,stdout);
]],
[wchar_t support])
#include <stdlib.h> is missing for the exit function.
This is still a large task as a result, but the cost of not doing this also
quite high in terms of time wasted on hunting down source code bugs the
compiler has already identified successfully.
