[libvirt] [PATCH] Improve compiler flag checking
# HG changeset patch
# User john.levon(a)sun.com
# Date 1229399267 28800
# Node ID 1f7707a3d49b20397011897cdc04c347322ad0c5
# Parent a6c317b5fe1b4081ccb40ba90af7d31298cf6b44
Improve compiler flag checking
Some compilers (including GCC) don't set the return value consistently
if an erroneous option is passed on the command line. Account for that.
Signed-off-by: John Levon <john.levon(a)sun.com>
diff --git a/acinclude.m4 b/acinclude.m4
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -45,21 +45,9 @@ AC_DEFUN([LIBVIRT_COMPILE_WARNINGS],[
;;
esac
- compiler_flags=
+ COMPILER_FLAGS=
for option in $try_compiler_flags; do
- SAVE_CFLAGS="$CFLAGS"
- CFLAGS="$CFLAGS $option"
- AC_MSG_CHECKING([whether gcc understands $option])
- AC_TRY_LINK([], [],
- has_option=yes,
- has_option=no,)
- CFLAGS="$SAVE_CFLAGS"
- AC_MSG_RESULT($has_option)
- if test $has_option = yes; then
- compiler_flags="$compiler_flags $option"
- fi
- unset has_option
- unset SAVE_CFLAGS
+ gl_COMPILER_FLAGS($option)
done
unset option
unset try_compiler_flags
@@ -85,7 +73,7 @@ AC_DEFUN([LIBVIRT_COMPILE_WARNINGS],[
fi
AC_MSG_RESULT($complCFLAGS)
- WARN_CFLAGS="$compiler_flags $complCFLAGS"
+ WARN_CFLAGS="$COMPILER_FLAGS $complCFLAGS"
AC_SUBST(WARN_CFLAGS)
])
diff --git a/m4/compiler-flags.m4 b/m4/compiler-flags.m4
--- a/m4/compiler-flags.m4
+++ b/m4/compiler-flags.m4
@@ -23,12 +23,14 @@ AC_DEFUN([gl_COMPILER_FLAGS],
AC_DEFUN([gl_COMPILER_FLAGS],
[AC_MSG_CHECKING(whether compiler accepts $1)
AC_SUBST(COMPILER_FLAGS)
- ac_save_CFLAGS="$CFLAGS"
- CFLAGS="$CFLAGS $1"
- AC_TRY_COMPILE(,
- [int x;],
- COMPILER_FLAGS="$COMPILER_FLAGS $1"
- AC_MSG_RESULT(yes),
- AC_MSG_RESULT(no))
- CFLAGS="$ac_save_CFLAGS"
+ echo 'int x;' >conftest.c
+ $CC $CFLAGS $1 -c conftest.c 2>conftest.err
+ ret=$?
+ if test $ret != 0 -o -s conftest.err; then
+ AC_MSG_RESULT(no)
+ else
+ AC_MSG_RESULT(yes)
+ COMPILER_FLAGS="$COMPILER_FLAGS $1"
+ fi
+ rm -f conftest*
])