Avoid using deref_mut

Author: maxcabrajac

compiler/rustc_builtin_macros/src/test_harness.rs

@@ -1,7 +1,6 @@
 // Code that generates a test runner to run all the tests in a crate
 
 use std::mem;
-use std::ops::DerefMut;
 
 use rustc_ast as ast;
 use rustc_ast::entry::EntryPointType;
@@ -130,8 +129,9 @@ impl<'a> MutVisitor for TestHarnessGenerator<'a> {
         c.items.push(mk_main(&mut self.cx));
     }
 
-    fn visit_item(&mut self, i: &mut P<ast::Item>) {
-        let item = i.deref_mut();
+    fn visit_item(&mut self, item: &mut P<ast::Item>) {
+        let item = &mut **item;
+
         if let Some(name) = get_test_name(&item) {
             debug!("this is a test item");
 
@@ -198,13 +198,11 @@ struct EntryPointCleaner<'a> {
 }
 
 impl<'a> MutVisitor for EntryPointCleaner<'a> {
-    fn visit_item(&mut self, i: &mut P<ast::Item>) {
+    fn visit_item(&mut self, item: &mut P<ast::Item>) {
         self.depth += 1;
-        ast::mut_visit::walk_item(self, i, ());
+        ast::mut_visit::walk_item(self, item, ());
         self.depth -= 1;
 
-        let item = i.deref_mut();
-
         // Remove any #[rustc_main] or #[start] from the AST so it doesn't
         // clash with the one we're going to add, but mark it as
         // #[allow(dead_code)] to avoid printing warnings.