Fix off_t/rlim_t size checks when cross-compiling

The current off_t/rlim_t size checks (wrt size of long long) use AC_RUN
which obviously doesn't work when cross-compiling.  While we don't hit
any configure errors, the fall back code is pretty dumb (which is to say
there isn't any).  Considering the code in question though, we can use
some fun compiler tricks with sizeof and array lengths to turn it into
a pure build test and avoid the RUN issue completely.

* m4/long_long.m4 (AC_OFF_T_IS_LONG_LONG, AC_RLIM_T_IS_LONG_LONG):
Convert from AC_RUN_IFELSE to AC_COMPILE_IFELSE.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

diff --git a/m4/long_long.m4 b/m4/long_long.m4
index 5c5c80aec1de4862399fb3ebb0293fd48c82094e..32ebdfd4410c4437890f72516815375758635ba5 100644 (file)
--- a/m4/long_long.m4
+++ b/m4/long_long.m4
@@ -2,16 +2,10 @@ dnl ### A macro to determine if off_t is a long long
 AC_DEFUN([AC_OFF_T_IS_LONG_LONG],
 [AC_MSG_CHECKING(for long long off_t)
 AC_CACHE_VAL(ac_cv_have_long_long_off_t,
-[AC_RUN_IFELSE([AC_LANG_SOURCE([[#include <sys/types.h>
-main () {
-       if (sizeof (off_t) == sizeof (long long) &&
-           sizeof (off_t) > sizeof (long))
-           return 0;
-       return 1;
-}
-]])],[ac_cv_have_long_long_off_t=yes],[ac_cv_have_long_long_off_t=no],[# Should try to guess here
-ac_cv_have_long_long_off_t=no
-])])
+[AC_COMPILE_IFELSE([AC_LANG_SOURCE([[#include <sys/types.h>
+char a[(sizeof (off_t) == sizeof (long long) &&
+        sizeof (off_t) > sizeof (long)) - 1];
+]])],[ac_cv_have_long_long_off_t=yes],[ac_cv_have_long_long_off_t=no])])
 AC_MSG_RESULT($ac_cv_have_long_long_off_t)
 if test "$ac_cv_have_long_long_off_t" = yes
 then
@@ -23,18 +17,12 @@ dnl ### A macro to determine if rlim_t is a long long
 AC_DEFUN([AC_RLIM_T_IS_LONG_LONG],
 [AC_MSG_CHECKING(for long long rlim_t)
 AC_CACHE_VAL(ac_cv_have_long_long_rlim_t,
-[AC_RUN_IFELSE([AC_LANG_SOURCE([[#include <sys/types.h>
+[AC_COMPILE_IFELSE([AC_LANG_SOURCE([[#include <sys/types.h>
 #include <sys/time.h>
 #include <sys/resource.h>
-main () {
-       if (sizeof (rlim_t) == sizeof (long long) &&
-           sizeof (rlim_t) > sizeof (long))
-           return 0;
-       return 1;
-}
-]])],[ac_cv_have_long_long_rlim_t=yes],[ac_cv_have_long_long_rlim_t=no],[# Should try to guess here
-ac_cv_have_long_long_rlim_t=no
-])])
+char a[(sizeof (rlim_t) == sizeof (long long) &&
+        sizeof (rlim_t) > sizeof (long)) - 1];
+]])],[ac_cv_have_long_long_rlim_t=yes],[ac_cv_have_long_long_rlim_t=no])])
 AC_MSG_RESULT($ac_cv_have_long_long_rlim_t)
 if test "$ac_cv_have_long_long_rlim_t" = yes
 then