Better detection of unsupported compiler options.

Should prevent "unsupported -Wl,-z,retpoline" warnings during linking.
ok djm@

1 files changed, 11 insertions, 4 deletions

diff --git a/aclocal.m4 b/aclocal.m4
index ac6b6684a..25ecc49a2 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -25,7 +25,7 @@ int main(int argc, char **argv) {
 }
         ]])],
                 [
-if `grep -i "unrecognized option" conftest.err >/dev/null`
+if $ac_cv_path_EGREP -i "unrecognized option|warning.*ignored" conftest.err >/dev/null
 then
                 AC_MSG_RESULT([no])
                 CFLAGS="$saved_CFLAGS"
@@ -63,7 +63,7 @@ int main(int argc, char **argv) {
 }
         ]])],
                 [
-if `grep -i "unrecognized option" conftest.err >/dev/null`
+if $ac_cv_path_EGREP -i "unrecognized option|warning.*ignored" conftest.err >/dev/null
 then
                 AC_MSG_RESULT([no])
                 CFLAGS="$saved_CFLAGS"
@@ -100,8 +100,15 @@ int main(int argc, char **argv) {
         exit(0);
 }
                 ]])],
-                [ AC_MSG_RESULT([yes])
-                  LDFLAGS="$saved_LDFLAGS $_define_flag"],
+                [
+if $ac_cv_path_EGREP -i "unrecognized option|warning.*ignored" conftest.err >/dev/null
+then
+                  AC_MSG_RESULT([no])
+                  LDFLAGS="$saved_LDFLAGS"
+else
+                  AC_MSG_RESULT([yes])
+                  LDFLAGS="$saved_LDFLAGS $_define_flag"
+fi              ],
                 [ AC_MSG_RESULT([no])
                   LDFLAGS="$saved_LDFLAGS" ]
         )