Remove unnecessary clones, document out_dir

src/cargo/core/compiler/context/compilation_files.rs

@@ -191,6 +191,8 @@ impl<'a, 'cfg: 'a> CompilationFiles<'a, 'cfg> {
     /// Returns the directory where the artifacts for the given unit are
     /// initially created.
     pub fn out_dir(&self, unit: &Unit) -> PathBuf {
+        // Docscrape units need to have doc/ set as the out_dir so sources for reverse-dependencies
+        // will be put into doc/ and not into deps/ where the *.examples files are stored.
         if unit.mode.is_doc() || unit.mode.is_doc_scrape() {
             self.layout(unit.kind).doc().to_path_buf()
         } else if unit.mode.is_doc_test() {

src/cargo/ops/cargo_compile.rs

@@ -229,7 +229,7 @@ impl Packages {
     }
 }
 
-#[derive(Debug, PartialEq, Eq, Clone)]
+#[derive(Debug, PartialEq, Eq)]
 pub enum LibRule {
     /// Include the library, fail if not present
     True,
@@ -239,13 +239,13 @@ pub enum LibRule {
     False,
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub enum FilterRule {
     All,
     Just(Vec<String>),
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub enum CompileFilter {
     Default {
         /// Flag whether targets can be safely skipped when required-features are not satisfied.