From 906d2537b9d0384985ed6259ef77ca1bd3d503ed Mon Sep 17 00:00:00 2001
From: Nicolas Williams <nico@cryptonector.com>
Date: Fri, 26 Dec 2014 14:37:38 -0600
Subject: [PATCH] Allow C-coded functions to `empty`

Just return a jv_invalid() without a message.
---
 execute.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/execute.c b/execute.c
index e8fba19d..231bd218 100644
--- a/execute.c
+++ b/execute.c
@@ -703,9 +703,13 @@ jv jq_next(jq_state *jq) {
       
       if (jv_is_valid(top)) {
         stack_push(jq, top);
-      } else {
+      } else if (jv_invalid_has_msg(jv_copy(top))) {
         set_error(jq, top);
         goto do_backtrack;
+      } else {
+        // C-coded function returns invalid w/o msg? -> backtrack, as if
+        // it had returned `empty`
+        goto do_backtrack;
       }
       break;
     }