Remove redundant clones

src/librustc_mir/monomorphize/partitioning.rs

@@ -585,7 +585,7 @@ fn merge_codegen_units<'tcx>(tcx: TyCtxt<'_, 'tcx, 'tcx>,
     // smallest into each other) we're sure to start off with a deterministic
     // order (sorted by name). This'll mean that if two cgus have the same size
     // the stable sort below will keep everything nice and deterministic.
-    codegen_units.sort_by_key(|cgu| cgu.name().clone());
+    codegen_units.sort_by_key(|cgu| *cgu.name());
 
     // Merge the two smallest codegen units until the target size is reached.
     while codegen_units.len() > target_cgu_count {
@@ -985,7 +985,7 @@ fn collect_and_partition_mono_items<'a, 'tcx>(
                 output.push_str(" @@");
                 let mut empty = Vec::new();
                 let cgus = item_to_cgus.get_mut(i).unwrap_or(&mut empty);
-                cgus.as_mut_slice().sort_by_cached_key(|&(ref name, _)| name.clone());
+                cgus.sort_by_key(|(name, _)| *name);
                 cgus.dedup();
                 for &(ref cgu_name, (linkage, _)) in cgus.iter() {
                     output.push_str(" ");

src/librustc_resolve/build_reduced_graph.rs

@@ -318,7 +318,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                         // This particular use tree
                         &tree, id, &prefix, true,
                         // The whole `use` item
-                        parent_scope.clone(), item, ty::Visibility::Invisible, root_span,
+                        parent_scope, item, ty::Visibility::Invisible, root_span,
                     );
                 }
             }

src/libsyntax/ext/tt/macro_parser.rs

@@ -309,7 +309,7 @@ fn create_matches(len: usize) -> Box<[Rc<NamedMatchVec>]> {
         vec![]
     } else {
         let empty_matches = Rc::new(SmallVec::new());
-        vec![empty_matches.clone(); len]
+        vec![empty_matches; len]
     }.into_boxed_slice()
 }