AC_TYPE_MBSTATE_T

[Stepan Kasal]

Hello,
        a problem related to detection of multibyte support was
raised by a bug report to gawk, the thread is archived at:
http://mail.gnu.org/archive/html/bug-gnu-utils/2003-07/msg00361.html

HP-UX 11.11 with GCC doesn't define mbstate_t in wchar.h, even though
functions mbrlen and mbrtowc are available.

It seems that wchar.h would include <sys/_mbstate_t.h>, if
_INCLUDE__STDC_A1_SOURCE were defined.
But defining this symbol breaks something else in the gawk source tree.

The next thing to try would be to include <sys/_mbstate_t.h>
before wchar.h .  Perhaps this could be encorporated into the
AC_TYPE_MBSTATE_T test?
(I haven't tried this yet, as I don't have access to the system.)

Or is it better to simply call AC_FUNC_MBRTOWC which would find out
that mbstate_t is not defined and would disable multibyte support
for that platform?

A somewhat related question:  why does AC_TYPE_MBSTATE_T define
mbstate_t if it is not defined by the headers?  Just so that declarations
of functions can contain it?  But the type may not actually be used on
such systems, right?

Thank you in advance for explanation,
        Stepan Kasal

PS: please cc me in the answer, if possible