Use Rust 2018 edition

Cargo.toml

@@ -3,6 +3,7 @@ name = "uluru"
 version = "2.1.1"
 authors = ["The Servo Project Developers", "Matt Brubeck <mbrubeck@limpet.net>"]
 license = "MPL-2.0"
+edition = "2018"
 description = "A simple, fast, LRU cache implementation"
 repository = "https://github.com/servo/uluru"
 keywords = ["cache", "linkedlist", "array", "no_std"]

src/lib.rs

@@ -12,10 +12,7 @@
 //!
 //! See the [`LRUCache`](LRUCache) docs for details.
 
-extern crate arrayvec;
-
 use arrayvec::ArrayVec;
-
 use core::fmt;
 
 #[cfg(test)]
@@ -206,15 +203,15 @@ impl<T, const N: usize> LRUCache<T, N> {
     }
 
     /// Iterate over the contents of this cache.
-    pub fn iter(&self) -> Iter<T, N> {
+    pub fn iter(&self) -> Iter<'_, T, N> {
         Iter {
             pos: self.head,
             cache: self,
         }
     }
 
     /// Iterate mutably over the contents of this cache.
-    fn iter_mut(&mut self) -> IterMut<T, N> {
+    fn iter_mut(&mut self) -> IterMut<'_, T, N> {
         IterMut {
             pos: self.head,
             cache: self,