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,
         }