gcc gives an error on an unknown warning flag, but clang just gives a warning. Upgrade the warning in clang to an error by activating -Werror=unknown-warning-option if available. Signed-off-by: Allan McRae <allan@archlinux.org> --- Tested with clang and gcc. Both give the right result. m4/acinclude.m4 | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/m4/acinclude.m4 b/m4/acinclude.m4 index e601f0e..294507e 100644 --- a/m4/acinclude.m4 +++ b/m4/acinclude.m4 @@ -114,6 +114,10 @@ AC_DEFUN([CFLAGS_ADD], [AS_VAR_PUSHDEF([my_cflags], [cflags_cv_warn_$1])dnl AC_CACHE_CHECK([whether compiler handles $1], [my_cflags], [ save_CFLAGS="$CFLAGS" + CFLAGS="${CFLAGS} -Werror=unknown-warning-option" + AC_COMPILE_IFELSE([AC_LANG_PROGRAM([])], + [], + [CFLAGS="$save_CFLAGS"]) CFLAGS="${CFLAGS} $1" AC_COMPILE_IFELSE([AC_LANG_PROGRAM([])], [AS_VAR_SET([my_cflags], [yes])], -- 1.8.1.3