From c7a787a3276cadad7ee51577f65158b4888c058c Mon Sep 17 00:00:00 2001
From: Vojtech Kral <vojtech@kral.hk>
Date: Fri, 16 Oct 2020 20:24:49 +0200
Subject: [PATCH] liballoc: VecDeque: Simplify binary_search_by()

---
 library/alloc/src/collections/vec_deque.rs | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/library/alloc/src/collections/vec_deque.rs b/library/alloc/src/collections/vec_deque.rs
index 6ba0a463da4..94dac1cd176 100644
--- a/library/alloc/src/collections/vec_deque.rs
+++ b/library/alloc/src/collections/vec_deque.rs
@@ -2516,24 +2516,13 @@ impl<T> VecDeque<T> {
     where
         F: FnMut(&'a T) -> Ordering,
     {
-        if self.is_empty() {
-            return Err(0);
-        }
-
         let (front, back) = self.as_slices();
 
-        match back.first().map(|elem| f(elem)) {
-            Some(Ordering::Equal) => return Ok(front.len()),
-            Some(Ordering::Less) => {
-                return back[1..]
-                    .binary_search_by(f)
-                    .map(|idx| idx + front.len() + 1)
-                    .map_err(|idx| idx + front.len() + 1);
-            }
-            _ => {}
+        if let Some(Ordering::Less | Ordering::Equal) = back.first().map(|elem| f(elem)) {
+            back.binary_search_by(f).map(|idx| idx + front.len()).map_err(|idx| idx + front.len())
+        } else {
+            front.binary_search_by(f)
         }
-
-        front.binary_search_by(f)
     }
 
     /// Binary searches this sorted `VecDeque` with a key extraction function.