# HG changeset patch # User john.levon@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@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* ])