From cf69e016b55fb2fecbd89367c780023ce3f91d94 Mon Sep 17 00:00:00 2001
From: Seyon Sivarajah <seyon.sivarajah@quantinuum.com>
Date: Wed, 3 Jan 2024 14:24:18 +0000
Subject: [PATCH] refactor: simplify removeconstignore verify (#768)

leftover review comment:
https://github.com/CQCL/hugr/pull/757#discussion_r1439399609
---
 src/hugr/rewrite/consts.rs | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/hugr/rewrite/consts.rs b/src/hugr/rewrite/consts.rs
index 6ac32a65a..2fee7a53d 100644
--- a/src/hugr/rewrite/consts.rs
+++ b/src/hugr/rewrite/consts.rs
@@ -45,11 +45,12 @@ impl Rewrite for RemoveConstIgnore {
         if (!h.contains_node(node)) || (!h.get_optype(node).is_load_constant()) {
             return Err(RemoveError::InvalidNode(node));
         }
-
-        if h.out_value_types(node)
-            .next()
-            .is_some_and(|(p, _)| h.linked_inputs(node, p).next().is_some())
-        {
+        let (p, _) = h
+            .out_value_types(node)
+            .exactly_one()
+            .ok()
+            .expect("LoadConstant has only one output.");
+        if h.linked_inputs(node, p).next().is_some() {
             return Err(RemoveError::ValueUsed(node));
         }