Fix core tests

Author: rylev

library/core/src/clone.rs

@@ -111,6 +111,7 @@ pub trait Clone: Sized {
     /// # Examples
     ///
     /// ```
+    /// # #![allow(noop_method_call)]
     /// let hello = "Hello"; // &str implements Clone
     ///
     /// assert_eq!("Hello", hello.clone());

library/core/tests/clone.rs

@@ -1,3 +1,5 @@
+#![allow(noop_method_call)]
+
 #[test]
 fn test_borrowed_clone() {
     let x = 5;

library/core/tests/iter/adapters/intersperse.rs

@@ -9,7 +9,7 @@ fn test_intersperse() {
     assert_eq!(v, vec![1]);
 
     let xs = ["a", "", "b", "c"];
-    let v: Vec<&str> = xs.iter().map(|x| x.clone()).intersperse(", ").collect();
+    let v: Vec<&str> = xs.iter().map(|x| *x).intersperse(", ").collect();
     let text: String = v.concat();
     assert_eq!(text, "a, , b, c".to_string());
 
@@ -24,7 +24,7 @@ fn test_intersperse_size_hint() {
     assert_eq!(iter.size_hint(), (0, Some(0)));
 
     let xs = ["a", "", "b", "c"];
-    let mut iter = xs.iter().map(|x| x.clone()).intersperse(", ");
+    let mut iter = xs.iter().map(|x| *x).intersperse(", ");
     assert_eq!(iter.size_hint(), (7, Some(7)));
 
     assert_eq!(iter.next(), Some("a"));