From 1d1ff8db7af7b7e3169df212a3b774c2bdfdc836 Mon Sep 17 00:00:00 2001
From: Jeong Yunwon <jeong@youknowone.org>
Date: Fri, 10 Jun 2022 11:44:42 +0900
Subject: [PATCH] wrap_index without abs

---
 vm/src/sliceable.rs | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/vm/src/sliceable.rs b/vm/src/sliceable.rs
index 8f1288cc49..7a4a3d0b5a 100644
--- a/vm/src/sliceable.rs
+++ b/vm/src/sliceable.rs
@@ -308,14 +308,15 @@ impl SequenceIndexOp for isize {
     }
 
     fn wrapped_at(&self, len: usize) -> Option<usize> {
-        let neg = self.is_negative();
-        let p = self.unsigned_abs();
-        if neg {
-            len.checked_sub(p)
-        } else if p >= len {
+        let mut p = *self;
+        if p < 0 {
+            // casting to isize is ok because it is used by wrapping_add
+            p = p.wrapping_add(len as isize);
+        }
+        if p < 0 || (p as usize) >= len {
             None
         } else {
-            Some(p)
+            Some(p as usize)
         }
     }
 }