From 79212bf652a66bdb03f3eb32ad56a3021899252b Mon Sep 17 00:00:00 2001
From: Andrew Davison <andrew.davison@gmail.com>
Date: Tue, 3 Oct 2023 08:30:03 +1000
Subject: [PATCH] WIP, re issue #354

---
 src/attributed.c | 8 ++++++--
 src/attributed.h | 2 +-
 src/query.c      | 4 ++--
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/attributed.c b/src/attributed.c
index c26512633..877dab44c 100644
--- a/src/attributed.c
+++ b/src/attributed.c
@@ -210,7 +210,7 @@ bool fn_sys_redo_trail_1(query * q)
 	return true;
 }
 
-bool do_post_unification_hook(query *q)
+bool do_post_unification_hook(query *q, bool is_builtin)
 {
 	q->run_hook = false;
 	q->undo_lo_tp = q->before_hook_tp;
@@ -249,7 +249,11 @@ bool do_post_unification_hook(query *q)
 	if (!tmp[1].match)
 		return throw_error(q, tmp+1, q->st.curr_frame, "existence_error", "procedure");
 
-	make_call_redo(q, tmp+2);
+	if (is_builtin)
+		make_call(q, tmp+2);
+	else
+		make_call_redo(q, tmp+2);
+
 	q->st.curr_cell = tmp;
 	return true;
 }
diff --git a/src/attributed.h b/src/attributed.h
index 3a063d28b..499b5d7ec 100644
--- a/src/attributed.h
+++ b/src/attributed.h
@@ -6,7 +6,7 @@ bool fn_sys_get_attributes_2(query *q);
 bool fn_sys_unattributed_var_1(query *q);
 bool fn_sys_attributed_var_1(query *q);
 
-bool do_post_unification_hook(query *q);
+bool do_post_unification_hook(query *q, bool is_builtin);
 bool fn_sys_undo_trail_2(query *q);
 bool fn_sys_redo_trail_1(query *q);
 
diff --git a/src/query.c b/src/query.c
index 321f0aa35..075dfc2c9 100644
--- a/src/query.c
+++ b/src/query.c
@@ -1581,7 +1581,7 @@ bool start(query *q)
 			}
 
 			if (q->run_hook)
-				do_post_unification_hook(q);
+				do_post_unification_hook(q, true);
 
 			Trace(q, save_cell, save_ctx, EXIT);
 			proceed(q);
@@ -1593,7 +1593,7 @@ bool start(query *q)
 			}
 
 			if (q->run_hook)
-				do_post_unification_hook(q);
+				do_post_unification_hook(q, false);
 		} else {
 			if (consultall(q, q->st.curr_cell, q->st.curr_frame) != true) {
 				q->retry = QUERY_RETRY;