Opt for .cloned() over .map(|x| x.clone()) etc.

src/libsyntax/ext/base.rs

@@ -639,7 +639,7 @@ impl<'a> ExtCtxt<'a> {
     pub fn mod_path(&self) -> Vec<ast::Ident> {
         let mut v = Vec::new();
         v.push(token::str_to_ident(&self.ecfg.crate_name[]));
-        v.extend(self.mod_path.iter().map(|a| *a));
+        v.extend(self.mod_path.iter().cloned());
         return v;
     }
     pub fn bt_push(&mut self, ei: ExpnInfo) {

src/libsyntax/ext/deriving/generic/mod.rs

@@ -367,7 +367,7 @@ impl<'a> TraitDef<'a> {
                 "allow" | "warn" | "deny" | "forbid" => true,
                 _ => false,
             }
-        }).map(|a| a.clone()));
+        }).cloned());
         push(P(ast::Item {
             attrs: attrs,
             ..(*newitem).clone()
@@ -410,7 +410,7 @@ impl<'a> TraitDef<'a> {
         let mut ty_params = ty_params.into_vec();
 
         // Copy the lifetimes
-        lifetimes.extend(generics.lifetimes.iter().map(|l| (*l).clone()));
+        lifetimes.extend(generics.lifetimes.iter().cloned());
 
         // Create the type parameters.
         ty_params.extend(generics.ty_params.iter().map(|ty_param| {
@@ -445,14 +445,14 @@ impl<'a> TraitDef<'a> {
                         span: self.span,
                         bound_lifetimes: wb.bound_lifetimes.clone(),
                         bounded_ty: wb.bounded_ty.clone(),
-                        bounds: OwnedSlice::from_vec(wb.bounds.iter().map(|b| b.clone()).collect())
+                        bounds: OwnedSlice::from_vec(wb.bounds.iter().cloned().collect())
                     })
                 }
                 ast::WherePredicate::RegionPredicate(ref rb) => {
                     ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
                         span: self.span,
                         lifetime: rb.lifetime,
-                        bounds: rb.bounds.iter().map(|b| b.clone()).collect()
+                        bounds: rb.bounds.iter().cloned().collect()
                     })
                 }
                 ast::WherePredicate::EqPredicate(ref we) => {
@@ -500,7 +500,7 @@ impl<'a> TraitDef<'a> {
         let opt_trait_ref = Some(trait_ref);
         let ident = ast_util::impl_pretty_name(&opt_trait_ref, &*self_type);
         let mut a = vec![attr];
-        a.extend(self.attributes.iter().map(|a| a.clone()));
+        a.extend(self.attributes.iter().cloned());
         cx.item(
             self.span,
             ident,

src/libsyntax/ext/source_util.rs

@@ -179,7 +179,7 @@ pub fn expand_include_bytes(cx: &mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
             return DummyResult::expr(sp);
         }
         Ok(bytes) => {
-            let bytes = bytes.iter().map(|x| *x).collect();
+            let bytes = bytes.iter().cloned().collect();
             base::MacExpr::new(cx.expr_lit(sp, ast::LitBinary(Rc::new(bytes))))
         }
     }

src/libsyntax/ext/tt/macro_parser.rs

@@ -283,7 +283,7 @@ pub fn parse(sess: &ParseSess,
              -> ParseResult {
     let mut cur_eis = Vec::new();
     cur_eis.push(initial_matcher_pos(Rc::new(ms.iter()
-                                                .map(|x| (*x).clone())
+                                                .cloned()
                                                 .collect()),
                                      None,
                                      rdr.peek().sp.lo));

src/libsyntax/ext/tt/macro_rules.rs

@@ -159,7 +159,7 @@ fn generic_extension<'cx>(cx: &'cx ExtCtxt,
                                                       None,
                                                       None,
                                                       arg.iter()
-                                                         .map(|x| (*x).clone())
+                                                         .cloned()
                                                          .collect(),
                                                       true);
             match parse(cx.parse_sess(), cx.cfg(), arg_rdr, lhs_tt) {