[BUG] AC_PATH_XTRA

[Morten Eriksen]

Hi,

given this configure.in (a useless case, but it'll serve as an
example):

== [snip] ====================================

AC_INIT(configure.in)
AC_CONFIG_HEADER(config.h)

if false; then
  AC_PATH_XTRA
else
  AC_PATH_XTRA
fi

AC_OUTPUT


== [snip] ====================================

..the resulting configure script will fail to define X_DISPLAY_MISSING
on systems without X11.

The reason for this is that AC_PATH_XTRA AC_REQUIREs AC_PATH_X, which
means it will only get expanded for the _first_ AC_PATH_XTRA in the
configure.in above, and then AC_PATH_XTRA uses

        test x"$no_x" = xyes

to decide whether or not to define X_DISPLAY_MISSING. But the
AC_PATH_X code will never be executed for the second AC_PATH_XTRA
above, so $no_x will never be set to anything at all.

(Autoconf's X11 checking is in general a mess, BTW.)

Regards,
Morten