Use .cloned() where appropriate

Fix most of Clippy’s map_clone warnings.

src/cargo/core/registry.rs

@@ -15,7 +15,7 @@ pub trait Registry {
 impl Registry for Vec<Summary> {
     fn query(&mut self, dep: &Dependency) -> CargoResult<Vec<Summary>> {
         Ok(self.iter().filter(|summary| dep.matches(*summary))
-               .map(|summary| summary.clone()).collect())
+               .cloned().collect())
     }
 }
 

src/cargo/ops/cargo_rustc/context.rs

@@ -213,7 +213,7 @@ impl<'a, 'cfg> Context<'a, 'cfg> {
         if unit.target.is_lib() && unit.profile.test {
             // Libs and their tests are built in parallel, so we need to make
             // sure that their metadata is different.
-            metadata.map(|m| m.clone()).map(|mut m| {
+            metadata.cloned().map(|mut m| {
                 m.mix(&"test");
                 m
             })
@@ -232,7 +232,7 @@ impl<'a, 'cfg> Context<'a, 'cfg> {
             // file names like `target/debug/libfoo.{a,so,rlib}` and such.
             None
         } else {
-            metadata.map(|m| m.clone())
+            metadata.cloned()
         }
     }
 

src/cargo/ops/resolve.rs

@@ -89,7 +89,7 @@ pub fn resolve_with_previous<'a>(registry: &mut PackageRegistry,
             for node in r.iter().filter(|p| keep(p, to_avoid, &to_avoid_sources)) {
                 let deps = r.deps(node).into_iter().flat_map(|i| i)
                             .filter(|p| keep(p, to_avoid, &to_avoid_sources))
-                            .map(|p| p.clone()).collect();
+                            .cloned().collect();
                 registry.register_lock(node.clone(), deps);
             }
 

src/cargo/sources/path.rs

@@ -312,7 +312,7 @@ impl<'cfg> Source for PathSource<'cfg> {
 
         Ok(self.packages.iter()
            .filter(|pkg| ids.iter().any(|id| pkg.package_id() == id))
-           .map(|pkg| pkg.clone())
+           .cloned()
            .collect())
     }
 

src/cargo/util/errors.rs

@@ -360,8 +360,8 @@ pub fn process_error(msg: &str,
 
     ProcessError {
         desc: desc,
-        exit: status.map(|a| a.clone()),
-        output: output.map(|a| a.clone()),
+        exit: status.cloned(),
+        output: output.cloned(),
         cause: cause,
     }
 }

src/cargo/util/graph.rs

@@ -21,7 +21,7 @@ impl<N: Eq + Hash + Clone> Graph<N> {
     }
 
     pub fn add(&mut self, node: N, children: &[N]) {
-        self.nodes.insert(node, children.iter().map(|n| n.clone()).collect());
+        self.nodes.insert(node, children.iter().cloned().collect());
     }
 
     pub fn link(&mut self, node: N, child: N) {