rustdoc: clippy::complexity fixes

clippy::map_flatten
clippy::clone_on_copy
clippy::useless_conversion
clippy::needless_arbitrary_self_type

src/librustdoc/clean/mod.rs

@@ -1533,9 +1533,7 @@ impl<'tcx> Clean<Type> for Ty<'tcx> {
                 for pb in obj.projection_bounds() {
                     bindings.push(TypeBinding {
                         name: cx.tcx.associated_item(pb.item_def_id()).name,
-                        kind: TypeBindingKind::Equality {
+                        kind: TypeBindingKind::Equality { term: pb.skip_binder().term.clean(cx) },
-                            term: pb.skip_binder().term.clean(cx).into(),
-                        },
                     });
                 }
 

src/librustdoc/clean/types.rs

@@ -1036,8 +1036,7 @@ impl Attributes {
         // Additional documentation should be shown before the original documentation
         let other_attrs = additional_attrs
             .into_iter()
-            .map(|(attrs, id)| attrs.iter().map(move |attr| (attr, Some(id))))
+            .flat_map(|(attrs, id)| attrs.iter().map(move |attr| (attr, Some(id))))
-            .flatten()
             .chain(attrs.iter().map(|attr| (attr, None)))
             .filter_map(clean_attr)
             .collect();

src/librustdoc/config.rs

@@ -439,13 +439,12 @@ impl Options {
             matches
                 .opt_str("default-theme")
                 .iter()
-                .map(|theme| {
+                .flat_map(|theme| {
                     vec![
                         ("use-system-theme".to_string(), "false".to_string()),
                         ("theme".to_string(), theme.to_string()),
                     ]
                 })
-                .flatten()
                 .collect(),
             matches
                 .opt_strs("default-setting")

src/librustdoc/html/format.rs

@@ -76,7 +76,7 @@ impl core::fmt::Write for Buffer {
     }
 
     #[inline]
-    fn write_fmt(self: &mut Self, args: fmt::Arguments<'_>) -> fmt::Result {
+    fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> fmt::Result {
         self.buffer.write_fmt(args)
     }
 }

src/librustdoc/html/highlight.rs

@@ -274,8 +274,7 @@ impl Decorations {
         let (mut starts, mut ends): (Vec<_>, Vec<_>) = info
             .0
             .into_iter()
-            .map(|(kind, ranges)| ranges.into_iter().map(move |(lo, hi)| ((lo, kind), hi)))
+            .flat_map(|(kind, ranges)| ranges.into_iter().map(move |(lo, hi)| ((lo, kind), hi)))
-            .flatten()
             .unzip();
 
         // Sort the sequences in document order.

src/librustdoc/html/render/search_index.rs

@@ -81,7 +81,7 @@ crate fn build_index<'tcx>(krate: &clean::Crate, cache: &mut Cache, tcx: TyCtxt<
                     lastpathid += 1;
 
                     if let Some(&(ref fqp, short)) = paths.get(&defid) {
-                        crate_paths.push((short, fqp.last().unwrap().clone()));
+                        crate_paths.push((short, *fqp.last().unwrap()));
                         Some(pathid)
                     } else {
                         None

src/librustdoc/scrape_examples.rs

@@ -247,8 +247,7 @@ crate fn run(
         let target_crates = options
             .target_crates
             .into_iter()
-            .map(|target| all_crates.iter().filter(move |(_, name)| name.as_str() == target))
+            .flat_map(|target| all_crates.iter().filter(move |(_, name)| name.as_str() == target))
-            .flatten()
             .map(|(crate_num, _)| **crate_num)
             .collect::<Vec<_>>();