From 564dcd49c671c3a60a09df39ace8e8dc943406ff Mon Sep 17 00:00:00 2001
From: Pascal Seitz <pascal.seitz@gmail.com>
Date: Thu, 25 Sep 2025 19:59:43 +0800
Subject: [PATCH] fix debug assert

---
 src/query/union/buffered_union.rs | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/query/union/buffered_union.rs b/src/query/union/buffered_union.rs
index 91f0c8ee4..9e0281dd6 100644
--- a/src/query/union/buffered_union.rs
+++ b/src/query/union/buffered_union.rs
@@ -17,9 +17,7 @@ const HORIZON: u32 = 64u32 * 64u32;
 //
 // Elements are dropped and not yielded.
 fn unordered_drain_filter<T, P>(v: &mut Vec<T>, mut predicate: P)
-where
-    P: FnMut(&mut T) -> bool,
-{
+where P: FnMut(&mut T) -> bool {
     let mut i = 0;
     while i < v.len() {
         if predicate(&mut v[i]) {
@@ -145,7 +143,8 @@ impl<TScorer: Scorer, TScoreCombiner: ScoreCombiner> BufferedUnionScorer<TScorer
     }
 
     fn is_in_horizon(&self, target: DocId) -> bool {
-        let gap = target - self.window_start_doc;
+        // wrapping_sub, because target may be < window_start_doc
+        let gap = target.wrapping_sub(self.window_start_doc);
         gap < HORIZON
     }
 }