From 17d11ebe6e9599d804c0378900b92a5a8054aec3 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Sat, 5 Jan 2019 16:16:08 +0100
Subject: [PATCH] be explicit about doing a binary search; fix out-of-bounds
 check

---
 src/range_map.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/range_map.rs b/src/range_map.rs
index d157cbf0549..d21f1ed8964 100644
--- a/src/range_map.rs
+++ b/src/range_map.rs
@@ -40,10 +40,11 @@ pub fn new(size: Size, init: T) -> RangeMap<T> {
 
     /// Find the index containing the given offset.
     fn find_offset(&self, offset: u64) -> usize {
-        debug_assert!(self.v.len() > 0);
+        // We do a binary search
         let mut left = 0usize; // inclusive
         let mut right = self.v.len(); // exclusive
         loop {
+            debug_assert!(left < right, "find_offset: offset {} is out-of-bounds", offset);
             let candidate = left.checked_add(right).unwrap() / 2;
             let elem = &self.v[candidate];
             if offset < elem.range.start {
@@ -54,7 +55,6 @@ fn find_offset(&self, offset: u64) -> usize {
                 // we are too far left (offset is further right)
                 debug_assert!(candidate >= left); // we are making progress
                 left = candidate+1;
-                debug_assert!(left < right, "find_offset: offset {} is out-of-bounds", offset);
             } else {
                 // This is it!
                 return candidate;
-- 
2.44.0