Derive Default in tests::hash

Author: estebank

Diff for: library/core/tests/hash/mod.rs

@@ -4,16 +4,11 @@ use std::hash::{BuildHasher, Hash, Hasher};
 use std::ptr;
 use std::rc::Rc;
 
+#[derive(Default)]
 struct MyHasher {
     hash: u64,
 }
 
-impl Default for MyHasher {
-    fn default() -> MyHasher {
-        MyHasher { hash: 0 }
-    }
-}
-
 impl Hasher for MyHasher {
     fn write(&mut self, buf: &[u8]) {
         for byte in buf {
@@ -107,6 +102,8 @@ fn test_writer_hasher() {
 struct Custom {
     hash: u64,
 }
+
+#[derive(Default)]
 struct CustomHasher {
     output: u64,
 }
@@ -123,12 +120,6 @@ impl Hasher for CustomHasher {
     }
 }
 
-impl Default for CustomHasher {
-    fn default() -> CustomHasher {
-        CustomHasher { output: 0 }
-    }
-}
-
 impl Hash for Custom {
     fn hash<H: Hasher>(&self, state: &mut H) {
         state.write_u64(self.hash);