From 8be071ab980c6080732daec565c35de242eaccf7 Mon Sep 17 00:00:00 2001
From: John Turner <jturner.usa@gmail.com>
Date: Tue, 25 Nov 2025 06:48:20 +0000
Subject: assert that iterator makes progress in Many combinator, in debug mode

---
 src/lib.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index e0c7fa0..0d5a164 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -445,10 +445,16 @@ where
         while !it.is_finished() {
             it = match self.parser.next::<OM, EM>(it.clone(), &mut state) {
                 Some(Ok((rest, output))) => {
+                    debug_assert!(
+                        rest.position() > it.position(),
+                        "iterator failed to make progress"
+                    );
+
                     outputs = OM::combine(outputs, output, |mut acc, e| {
                         acc.push(e);
                         acc
                     });
+
                     rest
                 }
                 _ => break,
-- 
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