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

Author: Ryman

src/compiletest/compiletest.rs

@@ -21,6 +21,7 @@
 #![feature(test)]
 #![feature(unicode)]
 #![feature(env)]
+#![feature(core)]
 
 #![deny(warnings)]
 

src/compiletest/runtest.rs

@@ -1133,7 +1133,7 @@ fn compile_test_(config: &Config, props: &TestProps,
     // FIXME (#9639): This needs to handle non-utf8 paths
     let mut link_args = vec!("-L".to_string(),
                              aux_dir.as_str().unwrap().to_string());
-    link_args.extend(extra_args.iter().map(|s| s.clone()));
+    link_args.extend(extra_args.iter().cloned());
     let args = make_compile_args(config,
                                  props,
                                  link_args,

src/libcollections/bit.rs

@@ -2306,7 +2306,7 @@ mod tests {
     #[test]
     fn test_from_bools() {
         let bools = vec![true, false, true, true];
-        let bitv: Bitv = bools.iter().map(|n| *n).collect();
+        let bitv: Bitv = bools.iter().cloned().collect();
         assert_eq!(format!("{:?}", bitv), "1011");
     }
 
@@ -2319,12 +2319,12 @@ mod tests {
     #[test]
     fn test_bitv_iterator() {
         let bools = vec![true, false, true, true];
-        let bitv: Bitv = bools.iter().map(|n| *n).collect();
+        let bitv: Bitv = bools.iter().cloned().collect();
 
         assert_eq!(bitv.iter().collect::<Vec<bool>>(), bools);
 
         let long: Vec<_> = (0i32..10000).map(|i| i % 2 == 0).collect();
-        let bitv: Bitv = long.iter().map(|n| *n).collect();
+        let bitv: Bitv = long.iter().cloned().collect();
         assert_eq!(bitv.iter().collect::<Vec<bool>>(), long)
     }
 

src/libcollections/dlist.rs

@@ -938,7 +938,7 @@ impl<A: Ord> Ord for DList<A> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A: Clone> Clone for DList<A> {
     fn clone(&self) -> DList<A> {
-        self.iter().map(|x| x.clone()).collect()
+        self.iter().cloned().collect()
     }
 }
 
@@ -1056,7 +1056,7 @@ mod tests {
 
     #[cfg(test)]
     fn list_from<T: Clone>(v: &[T]) -> DList<T> {
-        v.iter().map(|x| (*x).clone()).collect()
+        v.iter().cloned().collect()
     }
 
     #[test]

src/libcore/iter.rs

@@ -350,7 +350,7 @@ pub trait IteratorExt: Iterator + Sized {
     ///
     /// ```
     /// let xs = [100, 200, 300];
-    /// let mut it = xs.iter().map(|x| *x).peekable();
+    /// let mut it = xs.iter().cloned().peekable();
     /// assert_eq!(*it.peek().unwrap(), 100);
     /// assert_eq!(it.next().unwrap(), 100);
     /// assert_eq!(it.next().unwrap(), 200);

src/libcoretest/iter.rs

@@ -713,7 +713,7 @@ fn test_random_access_inspect() {
 fn test_random_access_map() {
     let xs = [1, 2, 3, 4, 5];
 
-    let mut it = xs.iter().map(|x| *x);
+    let mut it = xs.iter().cloned();
     assert_eq!(xs.len(), it.indexable());
     for (i, elt) in xs.iter().enumerate() {
         assert_eq!(Some(*elt), it.idx(i));

src/librustc/metadata/cstore.rs

@@ -139,8 +139,7 @@ impl CStore {
     pub fn get_used_crate_source(&self, cnum: ast::CrateNum)
                                      -> Option<CrateSource> {
         self.used_crate_sources.borrow_mut()
-            .iter().find(|source| source.cnum == cnum)
-            .map(|source| source.clone())
+            .iter().find(|source| source.cnum == cnum).cloned()
     }
 
     pub fn reset(&self) {
@@ -218,7 +217,7 @@ impl CStore {
 
     pub fn find_extern_mod_stmt_cnum(&self, emod_id: ast::NodeId)
                                      -> Option<ast::CrateNum> {
-        self.extern_mod_crate_map.borrow().get(&emod_id).map(|x| *x)
+        self.extern_mod_crate_map.borrow().get(&emod_id).cloned()
     }
 }
 

src/librustc/middle/check_match.rs

@@ -76,7 +76,7 @@ impl<'a> fmt::Debug for Matrix<'a> {
             pretty_printed_matrix.iter().map(|row| row[col].len()).max().unwrap_or(0)
         }).collect();
 
-        let total_width = column_widths.iter().map(|n| *n).sum() + column_count * 3 + 1;
+        let total_width = column_widths.iter().cloned().sum() + column_count * 3 + 1;
         let br = repeat('+').take(total_width).collect::<String>();
         try!(write!(f, "{}\n", br));
         for row in pretty_printed_matrix {

src/librustc/middle/const_eval.rs

@@ -501,7 +501,7 @@ fn lit_to_const(lit: &ast::Lit, ty_hint: Option<Ty>) -> const_val {
     match lit.node {
         ast::LitStr(ref s, _) => const_str((*s).clone()),
         ast::LitBinary(ref data) => {
-            const_binary(Rc::new(data.iter().map(|x| *x).collect()))
+            const_binary(data.clone())
         }
         ast::LitByte(n) => const_uint(n as u64),
         ast::LitChar(n) => const_uint(n as u64),

src/librustc/middle/dependency_format.rs

@@ -158,7 +158,7 @@ fn calculate_type(sess: &session::Session,
 
     // Collect what we've got so far in the return vector.
     let mut ret = (1..sess.cstore.next_crate_num()).map(|i| {
-        match formats.get(&i).map(|v| *v) {
+        match formats.get(&i).cloned() {
             v @ Some(cstore::RequireDynamic) => v,
             _ => None,
         }

src/librustc/middle/infer/error_reporting.rs

@@ -924,7 +924,7 @@ impl<'a, 'tcx> Rebuilder<'a, 'tcx> {
 
     fn rebuild(&self)
                -> (ast::FnDecl, Option<ast::ExplicitSelf_>, ast::Generics) {
-        let mut expl_self_opt = self.expl_self_opt.map(|x| x.clone());
+        let mut expl_self_opt = self.expl_self_opt.cloned();
         let mut inputs = self.fn_decl.inputs.clone();
         let mut output = self.fn_decl.output.clone();
         let mut ty_params = self.generics.ty_params.clone();

src/librustc/middle/lang_items.rs

@@ -147,18 +147,12 @@ struct LanguageItemCollector<'a> {
 
 impl<'a, 'v> Visitor<'v> for LanguageItemCollector<'a> {
     fn visit_item(&mut self, item: &ast::Item) {
-        match extract(&item.attrs) {
-            Some(value) => {
-                let item_index = self.item_refs.get(&value[]).map(|x| *x);
-
-                match item_index {
-                    Some(item_index) => {
-                        self.collect_item(item_index, local_def(item.id), item.span)
-                    }
-                    None => {}
-                }
+        if let Some(value) = extract(&item.attrs) {
+            let item_index = self.item_refs.get(&value[]).cloned();
+
+            if let Some(item_index) = item_index {
+                self.collect_item(item_index, local_def(item.id), item.span)
             }
-            None => {}
         }
 
         visit::walk_item(self, item);

src/librustc/middle/region.rs

@@ -407,7 +407,7 @@ impl RegionMaps {
 
     pub fn opt_encl_scope(&self, id: CodeExtent) -> Option<CodeExtent> {
         //! Returns the narrowest scope that encloses `id`, if any.
-        self.scope_map.borrow().get(&id).map(|x| *x)
+        self.scope_map.borrow().get(&id).cloned()
     }
 
     #[allow(dead_code)] // used in middle::cfg

src/librustc/middle/resolve_lifetime.rs

@@ -562,7 +562,7 @@ pub fn early_bound_lifetimes<'a>(generics: &'a ast::Generics) -> Vec<ast::Lifeti
 
     generics.lifetimes.iter()
         .filter(|l| referenced_idents.iter().any(|&i| i == l.lifetime.name))
-        .map(|l| (*l).clone())
+        .cloned()
         .collect()
 }
 

src/librustc/middle/traits/select.rs

@@ -738,7 +738,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     {
         let cache = self.pick_candidate_cache();
         let hashmap = cache.hashmap.borrow();
-        hashmap.get(&cache_fresh_trait_pred.0.trait_ref).map(|c| (*c).clone())
+        hashmap.get(&cache_fresh_trait_pred.0.trait_ref).cloned()
     }
 
     fn insert_candidate_cache(&mut self,

src/librustc/middle/ty.rs

@@ -2868,7 +2868,7 @@ pub fn mk_ctor_fn<'tcx>(cx: &ctxt<'tcx>,
                         def_id: ast::DefId,
                         input_tys: &[Ty<'tcx>],
                         output: Ty<'tcx>) -> Ty<'tcx> {
-    let input_args = input_tys.iter().map(|ty| *ty).collect();
+    let input_args = input_tys.iter().cloned().collect();
     mk_bare_fn(cx,
                Some(def_id),
                cx.mk_bare_fn(BareFnTy {
@@ -3837,7 +3837,7 @@ pub fn is_type_representable<'tcx>(cx: &ctxt<'tcx>, sp: Span, ty: Ty<'tcx>)
                                        -> Representability {
         match ty.sty {
             ty_tup(ref ts) => {
-                find_nonrepresentable(cx, sp, seen, ts.iter().map(|ty| *ty))
+                find_nonrepresentable(cx, sp, seen, ts.iter().cloned())
             }
             // Fixed-length vectors.
             // FIXME(#11924) Behavior undecided for zero-length vectors.
@@ -4965,7 +4965,7 @@ pub fn note_and_explain_type_err(cx: &ctxt, err: &type_err) {
 }
 
 pub fn provided_source(cx: &ctxt, id: ast::DefId) -> Option<ast::DefId> {
-    cx.provided_method_sources.borrow().get(&id).map(|x| *x)
+    cx.provided_method_sources.borrow().get(&id).cloned()
 }
 
 pub fn provided_trait_methods<'tcx>(cx: &ctxt<'tcx>, id: ast::DefId)

src/librustc/util/common.rs

@@ -214,7 +214,7 @@ pub fn memoized<T, U, S, F>(cache: &RefCell<HashMap<T, U, S>>, arg: T, f: F) ->
           F: FnOnce(T) -> U,
 {
     let key = arg.clone();
-    let result = cache.borrow().get(&key).map(|result| result.clone());
+    let result = cache.borrow().get(&key).cloned();
     match result {
         Some(result) => result,
         None => {

src/librustc_back/rpath.rs

@@ -40,10 +40,7 @@ pub fn get_rpath_flags<F, G>(config: RPathConfig<F, G>) -> Vec<String> where
     debug!("preparing the RPATH!");
 
     let libs = config.used_crates.clone();
-    let libs = libs.into_iter().filter_map(|(_, l)| {
-        l.map(|p| p.clone())
-    }).collect::<Vec<_>>();
-
+    let libs = libs.into_iter().filter_map(|(_, l)| l).collect::<Vec<_>>();
     let rpaths = get_rpaths(config, &libs[]);
     flags.push_all(&rpaths_to_flags(&rpaths[])[]);
     flags

src/librustc_driver/test.rs

@@ -254,7 +254,7 @@ impl<'a, 'tcx> Env<'a, 'tcx> {
                 output_ty: Ty<'tcx>)
                 -> Ty<'tcx>
     {
-        let input_args = input_tys.iter().map(|ty| *ty).collect();
+        let input_args = input_tys.iter().cloned().collect();
         ty::mk_bare_fn(self.infcx.tcx,
                        None,
                        self.infcx.tcx.mk_bare_fn(ty::BareFnTy {

src/librustc_resolve/lib.rs

@@ -1920,18 +1920,15 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                                 -> ResolveResult<(Rc<Module>, LastPrivate)> {
         fn search_parent_externals(needle: Name, module: &Rc<Module>)
                                 -> Option<Rc<Module>> {
-            module.external_module_children.borrow()
-                                            .get(&needle).cloned()
-                                            .map(|_| module.clone())
-                                            .or_else(|| {
-                match module.parent_link.clone() {
-                    ModuleParentLink(parent, _) => {
-                        search_parent_externals(needle,
-                                                &parent.upgrade().unwrap())
+            match module.external_module_children.borrow().get(&needle) {
+                Some(_) => Some(module.clone()),
+                None => match module.parent_link {
+                    ModuleParentLink(ref parent, _) => {
+                        search_parent_externals(needle, &parent.upgrade().unwrap())
                     }
                    _ => None
                 }
-            })
+            }
         }
 
         let mut search_module = module_;

src/librustc_trans/trans/base.rs

@@ -3211,7 +3211,7 @@ pub fn trans_crate<'tcx>(analysis: ty::CrateAnalysis<'tcx>)
     reachable.push("rust_eh_personality_catch".to_string());
 
     if codegen_units > 1 {
-        internalize_symbols(&shared_ccx, &reachable.iter().map(|x| x.clone()).collect());
+        internalize_symbols(&shared_ccx, &reachable.iter().cloned().collect());
     }
 
     let metadata_module = ModuleTranslation {

src/librustc_trans/trans/expr.rs

@@ -1197,7 +1197,7 @@ fn trans_rvalue_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
                 let trait_ref =
                     bcx.tcx().object_cast_map.borrow()
                                              .get(&expr.id)
-                                             .map(|t| (*t).clone())
+                                             .cloned()
                                              .unwrap();
                 let trait_ref = bcx.monomorphize(&trait_ref);
                 let datum = unpack_datum!(bcx, trans(bcx, &**val));

src/librustc_trans/trans/type_of.rs

@@ -67,7 +67,7 @@ pub fn untuple_arguments_if_necessary<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
                                                 abi: abi::Abi)
                                                 -> Vec<Ty<'tcx>> {
     if abi != abi::RustCall {
-        return inputs.iter().map(|x| (*x).clone()).collect()
+        return inputs.iter().cloned().collect()
     }
 
     if inputs.len() == 0 {

src/librustc_typeck/check/mod.rs

@@ -3220,7 +3220,7 @@ fn check_expr_with_unifier<'a, 'tcx, F>(fcx: &FnCtxt<'a, 'tcx>,
         for field in ast_fields {
             let mut expected_field_type = tcx.types.err;
 
-            let pair = class_field_map.get(&field.ident.node.name).map(|x| *x);
+            let pair = class_field_map.get(&field.ident.node.name).cloned();
             match pair {
                 None => {
                     fcx.type_error_message(
@@ -3852,7 +3852,7 @@ fn check_expr_with_unifier<'a, 'tcx, F>(fcx: &FnCtxt<'a, 'tcx>,
       }
       ast::ExprStruct(ref path, ref fields, ref base_expr) => {
         // Resolve the path.
-        let def = tcx.def_map.borrow().get(&id).map(|i| *i);
+        let def = tcx.def_map.borrow().get(&id).cloned();
         let struct_id = match def {
             Some(def::DefVariant(enum_id, variant_id, true)) => {
                 check_struct_enum_variant(fcx, id, expr.span, enum_id,

src/librustdoc/passes.rs

@@ -293,7 +293,7 @@ pub fn collapse_docs(krate: clean::Crate) -> plugins::PluginResult {
             let mut a: Vec<clean::Attribute> = i.attrs.iter().filter(|&a| match a {
                 &clean::NameValue(ref x, _) if "doc" == *x => false,
                 _ => true
-            }).map(|x| x.clone()).collect();
+            }).cloned().collect();
             if docstr.len() > 0 {
                 a.push(clean::NameValue("doc".to_string(), docstr));
             }

src/librustdoc/visit_ast.rs

@@ -333,7 +333,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                     name: name,
                     items: items.clone(),
                     generics: gen.clone(),
-                    bounds: b.iter().map(|x| (*x).clone()).collect(),
+                    bounds: b.iter().cloned().collect(),
                     id: item.id,
                     attrs: item.attrs.clone(),
                     whence: item.span,

src/libstd/env.rs

@@ -918,7 +918,7 @@ mod tests {
     #[cfg(unix)]
     fn join_paths_unix() {
         fn test_eq(input: &[&str], output: &str) -> bool {
-            &*join_paths(input.iter().map(|s| *s)).unwrap() ==
+            &*join_paths(input.iter().cloned()).unwrap() ==
                 OsStr::from_str(output)
         }
 
@@ -927,14 +927,14 @@ mod tests {
                          "/bin:/usr/bin:/usr/local/bin"));
         assert!(test_eq(&["", "/bin", "", "", "/usr/bin", ""],
                          ":/bin:::/usr/bin:"));
-        assert!(join_paths(["/te:st"].iter().map(|s| *s)).is_err());
+        assert!(join_paths(["/te:st"].iter().cloned()).is_err());
     }
 
     #[test]
     #[cfg(windows)]
     fn join_paths_windows() {
         fn test_eq(input: &[&str], output: &str) -> bool {
-            &*join_paths(input.iter().map(|s| *s)).unwrap() ==
+            &*join_paths(input.iter().cloned()).unwrap() ==
                 OsStr::from_str(output)
         }
 
@@ -945,6 +945,6 @@ mod tests {
                         r";c:\windows;;;c:\;"));
         assert!(test_eq(&[r"c:\te;st", r"c:\"],
                         r#""c:\te;st";c:\"#));
-        assert!(join_paths([r#"c:\te"st"#].iter().map(|s| *s)).is_err());
+        assert!(join_paths([r#"c:\te"st"#].iter().cloned()).is_err());
     }
     }

src/libsyntax/ast_map/mod.rs

@@ -251,7 +251,7 @@ impl<'ast> Map<'ast> {
     }
 
     fn find_entry(&self, id: NodeId) -> Option<MapEntry<'ast>> {
-        self.map.borrow().get(id as usize).map(|e| *e)
+        self.map.borrow().get(id as usize).cloned()
     }
 
     pub fn krate(&self) -> &'ast Crate {

src/libsyntax/diagnostics/registry.rs

@@ -21,6 +21,6 @@ impl Registry {
     }
 
     pub fn find_description(&self, code: &str) -> Option<&'static str> {
-        self.descriptions.get(code).map(|desc| *desc)
+        self.descriptions.get(code).cloned()
     }
 }

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) {