Replace map(|x| *x) with cloned().

This partially resolves rust-lang#22243.

Author: ruuda

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/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/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/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_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/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/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/libtest/lib.rs

@@ -938,7 +938,7 @@ fn calc_result(desc: &TestDesc, task_result: Result<(), Box<Any+Send>>) -> TestR
         (&ShouldFail::Yes(Some(msg)), Err(ref err))
             if err.downcast_ref::<String>()
                 .map(|e| &**e)
-                .or_else(|| err.downcast_ref::<&'static str>().map(|e| *e))
+                .or_else(|| err.downcast_ref::<&'static str>().cloned())
                 .map(|e| e.contains(msg))
                 .unwrap_or(false) => TrOk,
         _ => TrFailed,

src/test/bench/shootout-fasta.rs

@@ -133,7 +133,7 @@ fn run<W: Writer>(writer: &mut W) -> std::old_io::IoResult<()> {
                         ('t', 0.3015094502008)];
 
     try!(make_fasta(writer, ">ONE Homo sapiens alu\n",
-                    alu.as_bytes().iter().cycle().map(|c| *c), n * 2));
+                    alu.as_bytes().iter().cycle().cloned(), n * 2));
     try!(make_fasta(writer, ">TWO IUB ambiguity codes\n",
                     AAGen::new(rng, iub), n * 3));
     try!(make_fasta(writer, ">THREE Homo sapiens frequency\n",

src/test/bench/shootout-meteor.rs

@@ -270,7 +270,7 @@ fn handle_sol(raw_sol: &List<u64>, data: &mut Data) {
     // reverse order, i.e. the board rotated by half a turn.
     data.nb += 2;
     let sol1 = to_vec(raw_sol);
-    let sol2: Vec<u8> = sol1.iter().rev().map(|x| *x).collect();
+    let sol2: Vec<u8> = sol1.iter().rev().cloned().collect();
 
     if data.nb == 2 {
         data.min = sol1.clone();