This doesn't seem necessary?

src/librustdoc/clean/mod.rs

@@ -507,12 +507,6 @@ impl attr::AttrMetaMethods for Attribute {
  fn meta_item_list<'a>(&'a self) -> Option<&'a [P<ast::MetaItem>]> { None }
  fn span(&self) -> codemap::Span { unimplemented!() }
 }
-impl<'a> attr::AttrMetaMethods for &'a Attribute {
- fn name(&self) -> InternedString { (**self).name() }
- fn value_str(&self) -> Option<InternedString> { (**self).value_str() }
- fn meta_item_list(&self) -> Option<&[P<ast::MetaItem>]> { None }
- fn span(&self) -> codemap::Span { unimplemented!() }
-}
 
 #[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Debug)]
 pub struct TyParam {

src/librustdoc/fold.rs

@@ -9,8 +9,6 @@
 // except according to those terms.
 
 use clean::*;
-use std::collections::HashMap;
-use std::mem::{replace, swap};
 
 pub trait DocFolder : Sized {
  fn fold_item(&mut self, item: Item) -> Option<Item> {
@@ -20,42 +18,36 @@ pub trait DocFolder : Sized {
  /// don't override!
  fn fold_item_recur(&mut self, item: Item) -> Option<Item> {
  let Item { attrs, name, source, visibility, def_id, inner, stability, deprecation } = item;
- let inner = inner;
  let inner = match inner {
  StructItem(mut i) => {
- let mut foo = Vec::new(); swap(&mut foo, &mut i.fields);
- let num_fields = foo.len();
- i.fields.extend(foo.into_iter().filter_map(|x| self.fold_item(x)));
+ let num_fields = i.fields.len();
+ i.fields = i.fields.into_iter().filter_map(|x| self.fold_item(x)).collect();
  i.fields_stripped |= num_fields != i.fields.len();
  StructItem(i)
  },
  ModuleItem(i) => {
  ModuleItem(self.fold_mod(i))
  },
  EnumItem(mut i) => {
- let mut foo = Vec::new(); swap(&mut foo, &mut i.variants);
- let num_variants = foo.len();
- i.variants.extend(foo.into_iter().filter_map(|x| self.fold_item(x)));
+ let num_variants = i.variants.len();
+ i.variants = i.variants.into_iter().filter_map(|x| self.fold_item(x)).collect();
  i.variants_stripped |= num_variants != i.variants.len();
  EnumItem(i)
  },
  TraitItem(mut i) => {
- let mut foo = Vec::new(); swap(&mut foo, &mut i.items);
- i.items.extend(foo.into_iter().filter_map(|x| self.fold_item(x)));
+ i.items = i.items.into_iter().filter_map(|x| self.fold_item(x)).collect();
  TraitItem(i)
  },
  ImplItem(mut i) => {
- let mut foo = Vec::new(); swap(&mut foo, &mut i.items);
- i.items.extend(foo.into_iter().filter_map(|x| self.fold_item(x)));
+ i.items = i.items.into_iter().filter_map(|x| self.fold_item(x)).collect();
  ImplItem(i)
  },
  VariantItem(i) => {
  let i2 = i.clone(); // this clone is small
  match i.kind {
  StructVariant(mut j) => {
- let mut foo = Vec::new(); swap(&mut foo, &mut j.fields);
- let num_fields = foo.len();
- j.fields.extend(foo.into_iter().filter_map(|x| self.fold_item(x)));
+ let num_fields = j.fields.len();
+ j.fields = j.fields.into_iter().filter_map(|x| self.fold_item(x)).collect();
  j.fields_stripped |= num_fields != j.fields.len();
  VariantItem(Variant {kind: StructVariant(j), ..i2})
  },
@@ -78,17 +70,13 @@ pub trait DocFolder : Sized {
  }
 
  fn fold_crate(&mut self, mut c: Crate) -> Crate {
- c.module = match replace(&mut c.module, None) {
- Some(module) => self.fold_item(module), None => None
- };
-
- let external_traits = replace(&mut c.external_traits, HashMap::new());
- c.external_traits = external_traits.into_iter().map(|(k, mut v)| {
- let items = replace(&mut v.items, Vec::new());
- v.items = items.into_iter().filter_map(|i| self.fold_item(i))
- .collect();
+ c.module = c.module.and_then(|module| {
+ self.fold_item(module)
+ });
+ c.external_traits = c.external_traits.into_iter().map(|(k, mut v)| {
+ v.items = v.items.into_iter().filter_map(|i| self.fold_item(i)).collect();
  (k, v)
  }).collect();
- return c;
+ c
  }
 }

src/librustdoc/html/render.rs

@@ -374,7 +374,7 @@ fn init_ids() -> HashMap<String, usize> {
  "deref-methods",
  "implementations",
  "derived_implementations"
- ].into_iter().map(|id| (String::from(*id), 1)).collect::<HashMap<_, _>>()
+ ].into_iter().map(|id| (String::from(*id), 1)).collect()
 }
 
 /// This method resets the local table of used ID attributes. This is typically

src/librustdoc/passes.rs

@@ -243,8 +243,7 @@ impl<'a> fold::DocFolder for ImplStripper<'a> {
 pub fn unindent_comments(krate: clean::Crate) -> plugins::PluginResult {
  struct CommentCleaner;
  impl fold::DocFolder for CommentCleaner {
- fn fold_item(&mut self, i: Item) -> Option<Item> {
- let mut i = i;
+ fn fold_item(&mut self, mut i: Item) -> Option<Item> {
  let mut avec: Vec<clean::Attribute> = Vec::new();
  for attr in &i.attrs {
  match attr {
@@ -268,9 +267,8 @@ pub fn unindent_comments(krate: clean::Crate) -> plugins::PluginResult {
 pub fn collapse_docs(krate: clean::Crate) -> plugins::PluginResult {
  struct Collapser;
  impl fold::DocFolder for Collapser {
- fn fold_item(&mut self, i: Item) -> Option<Item> {
+ fn fold_item(&mut self, mut i: Item) -> Option<Item> {
  let mut docstr = String::new();
- let mut i = i;
  for attr in &i.attrs {
  if let clean::NameValue(ref x, ref s) = *attr {
  if "doc" == *x {