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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>
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1 parent 6d12afd commit 584ba2d31d3e37c82750dac4500838bafc8d427a @vapier vapier committed with ldv-alt Sep 12, 2010
Showing with 8 additions and 20 deletions.
  1. +8 −20 m4/long_long.m4
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@@ -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

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