Rollup merge of #22276 - ruud-v-a:map-clone, r=nikomatsakis

This resolves #22243 for the single-letter variables that I could grep. Some occurences could not be replaced.

Author: steveklabnik

src/libcollections/bit.rs

@@ -2282,7 +2282,7 @@ 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");
     }
 
@@ -2295,12 +2295,12 @@ 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

@@ -895,7 +895,7 @@ 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()
     }
 }
 
@@ -1013,7 +1013,7 @@ 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

@@ -325,7 +325,7 @@ 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

@@ -218,7 +218,7 @@ 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

@@ -75,7 +75,7 @@ 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

@@ -600,7 +600,7 @@ pub fn lit_to_const(lit: &ast::Lit) -> 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(Rc::new(data.iter().cloned().collect()))
         }
         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

@@ -149,7 +149,7 @@ 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);
+                let item_index = self.item_refs.get(&value[]).cloned();
 
                 match item_index {
                     Some(item_index) => {

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

@@ -4944,7 +4944,7 @@ 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_trans/trans/base.rs

@@ -3228,7 +3228,7 @@ 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

@@ -1153,7 +1153,7 @@ 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

@@ -3223,7 +3223,7 @@ 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(
@@ -3871,7 +3871,7 @@ 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/libstd/sys/windows/thread_local.rs

@@ -244,7 +244,7 @@ unsafe fn run_dtors() {
             let ret = if DTORS.is_null() {
                 Vec::new()
             } else {
-                (*DTORS).iter().map(|s| *s).collect()
+                (*DTORS).iter().cloned().collect()
             };
             DTOR_LOCK.unlock();
             ret

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/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

@@ -282,9 +282,7 @@ pub fn parse(sess: &ParseSess,
              ms: &[TokenTree])
              -> ParseResult {
     let mut cur_eis = Vec::new();
-    cur_eis.push(initial_matcher_pos(Rc::new(ms.iter()
-                                                .map(|x| (*x).clone())
-                                                .collect()),
+    cur_eis.push(initial_matcher_pos(Rc::new(ms.iter().cloned().collect()),
                                      None,
                                      rdr.peek().sp.lo));
 

src/libsyntax/ext/tt/macro_rules.rs

@@ -160,7 +160,7 @@ 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) {

src/libsyntax/parse/lexer/comments.rs

@@ -82,7 +82,7 @@ pub fn strip_doc_comment_decoration(comment: &str) -> String {
         while j > i && lines[j - 1].trim().is_empty() {
             j -= 1;
         }
-        return lines[i..j].iter().map(|x| (*x).clone()).collect();
+        return lines[i..j].iter().cloned().collect();
     }
 
     /// remove a "[ \t]*\*" block from each line, if possible

src/libsyntax/parse/parser.rs

@@ -241,7 +241,7 @@ macro_rules! maybe_whole {
 fn maybe_append(mut lhs: Vec<Attribute>, rhs: Option<Vec<Attribute>>)
                 -> Vec<Attribute> {
     match rhs {
-        Some(ref attrs) => lhs.extend(attrs.iter().map(|a| a.clone())),
+        Some(ref attrs) => lhs.extend(attrs.iter().cloned()),
         None => {}
     }
     lhs
@@ -467,7 +467,7 @@ impl<'a> Parser<'a> {
         debug!("commit_expr {:?}", e);
         if let ExprPath(..) = e.node {
             // might be unit-struct construction; check for recoverableinput error.
-            let mut expected = edible.iter().map(|x| x.clone()).collect::<Vec<_>>();
+            let mut expected = edible.iter().cloned().collect::<Vec<_>>();
             expected.push_all(inedible);
             self.check_for_erroneous_unit_struct_expecting(&expected[]);
         }
@@ -485,7 +485,7 @@ impl<'a> Parser<'a> {
         if self.last_token
                .as_ref()
                .map_or(false, |t| t.is_ident() || t.is_path()) {
-            let mut expected = edible.iter().map(|x| x.clone()).collect::<Vec<_>>();
+            let mut expected = edible.iter().cloned().collect::<Vec<_>>();
             expected.push_all(&inedible[]);
             self.check_for_erroneous_unit_struct_expecting(
                 &expected[]);

src/libsyntax/print/pprust.rs

@@ -983,7 +983,7 @@ impl<'a> State<'a> {
                 try!(self.word_nbsp("trait"));
                 try!(self.print_ident(item.ident));
                 try!(self.print_generics(generics));
-                let bounds: Vec<_> = bounds.iter().map(|b| b.clone()).collect();
+                let bounds: Vec<_> = bounds.iter().cloned().collect();
                 let mut real_bounds = Vec::with_capacity(bounds.len());
                 for b in bounds {
                     if let TraitTyParamBound(ref ptr, ast::TraitBoundModifier::Maybe) = b {