From 9d412718df6b40960cd1bd5dda44c9a5ac331f18 Mon Sep 17 00:00:00 2001
From: niftynei <niftynei@gmail.com>
Date: Thu, 8 Oct 2020 17:26:04 -0500
Subject: [PATCH] psbt: save the index of the change on the 'parent'

Note that for removals, the index will be on the original; for
additions, the index will be on the new. Yes this is implicit.
---
 common/psbt_open.c | 1 +
 common/psbt_open.h | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/common/psbt_open.c b/common/psbt_open.c
index 9137ccf86..4b65f431f 100644
--- a/common/psbt_open.c
+++ b/common/psbt_open.c
@@ -219,6 +219,7 @@ void psbt_sort_by_serial_id(struct wally_psbt *psbt)
 		struct type##_set a;				\
 		a.type = from->type##s[index];			\
 		a.tx_##type = from->tx->type##s[index]; 	\
+		a.idx = index;					\
 		tal_arr_expand(&add_to, a);			\
 	} while (0)
 
diff --git a/common/psbt_open.h b/common/psbt_open.h
index 3fb20865d..08efd46df 100644
--- a/common/psbt_open.h
+++ b/common/psbt_open.h
@@ -19,11 +19,15 @@ struct wally_map;
 struct input_set {
 	struct wally_tx_input tx_input;
 	struct wally_psbt_input input;
+	/* index on PSBT of this input */
+	size_t idx;
 };
 
 struct output_set {
 	struct wally_tx_output tx_output;
 	struct wally_psbt_output output;
+	/* index on PSBT of this output */
+	size_t idx;
 };
 
 struct psbt_changeset {