Auto merge of #141573 - nnethercote:rustdoc-alloc-cleanups, r=camelid

rustdoc: cleanups relating to allocations

These commits generally clean up the code a bit and also reduce allocation rates a bit.

r? `@camelid`

4 files changed, 53 insertions, 43 deletions

diff --git a/src/librustdoc/html/render/context.rs b/src/librustdoc/html/render/context.rs
index 1f7201b8ca8..5984dcd74ca 100644
--- a/src/librustdoc/html/render/context.rs
+++ b/src/librustdoc/html/render/context.rs
@@ -14,7 +14,7 @@ use rustc_span::edition::Edition;
 use rustc_span::{FileName, Symbol, sym};
 use tracing::info;
 
-use super::print_item::{full_path, item_path, print_item};
+use super::print_item::{full_path, print_item, print_item_path};
 use super::sidebar::{ModuleLike, Sidebar, print_sidebar, sidebar_module_like};
 use super::{AllTypes, LinkFromSrc, StylePath, collect_spans_and_sources, scrape_examples_help};
 use crate::clean::types::ExternalLocation;
@@ -266,7 +266,7 @@ impl<'tcx> Context<'tcx> {
                         for name in &names[..names.len() - 1] {
                             write!(f, "{name}/")?;
                         }
-                        write!(f, "{}", item_path(ty, names.last().unwrap().as_str()))
+                        write!(f, "{}", print_item_path(ty, names.last().unwrap().as_str()))
                     });
                     match self.shared.redirections {
                         Some(ref redirections) => {
@@ -278,7 +278,7 @@ impl<'tcx> Context<'tcx> {
                             let _ = write!(
                                 current_path,
                                 "{}",
-                                item_path(ty, names.last().unwrap().as_str())
+                                print_item_path(ty, names.last().unwrap().as_str())
                             );
                             redirections.borrow_mut().insert(current_path, path.to_string());
                         }
@@ -847,7 +847,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
         if !buf.is_empty() {
             let name = item.name.as_ref().unwrap();
             let item_type = item.type_();
-            let file_name = item_path(item_type, name.as_str()).to_string();
+            let file_name = print_item_path(item_type, name.as_str()).to_string();
             self.shared.ensure_dir(&self.dst)?;
             let joint_dst = self.dst.join(&file_name);
             self.shared.fs.write(joint_dst, buf)?;
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index 5677b13033d..66d5aafa3c1 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -2548,7 +2548,7 @@ fn item_ty_to_section(ty: ItemType) -> ItemSection {
 /// types are re-exported, we don't use the corresponding
 /// entry from the js file, as inlining will have already
 /// picked up the impl
-fn collect_paths_for_type(first_ty: clean::Type, cache: &Cache) -> Vec<String> {
+fn collect_paths_for_type(first_ty: &clean::Type, cache: &Cache) -> Vec<String> {
     let mut out = Vec::new();
     let mut visited = FxHashSet::default();
     let mut work = VecDeque::new();
@@ -2565,7 +2565,7 @@ fn collect_paths_for_type(first_ty: clean::Type, cache: &Cache) -> Vec<String> {
     work.push_back(first_ty);
 
     while let Some(ty) = work.pop_front() {
-        if !visited.insert(ty.clone()) {
+        if !visited.insert(ty) {
             continue;
         }
 
@@ -2575,16 +2575,16 @@ fn collect_paths_for_type(first_ty: clean::Type, cache: &Cache) -> Vec<String> {
                 work.extend(tys.into_iter());
             }
             clean::Type::Slice(ty) => {
-                work.push_back(*ty);
+                work.push_back(ty);
             }
             clean::Type::Array(ty, _) => {
-                work.push_back(*ty);
+                work.push_back(ty);
             }
             clean::Type::RawPointer(_, ty) => {
-                work.push_back(*ty);
+                work.push_back(ty);
             }
             clean::Type::BorrowedRef { type_, .. } => {
-                work.push_back(*type_);
+                work.push_back(type_);
             }
             clean::Type::QPath(box clean::QPathData { self_type, trait_, .. }) => {
                 work.push_back(self_type);
diff --git a/src/librustdoc/html/render/print_item.rs b/src/librustdoc/html/render/print_item.rs
index b4663961c1b..a75088d27cc 100644
--- a/src/librustdoc/html/render/print_item.rs
+++ b/src/librustdoc/html/render/print_item.rs
@@ -413,7 +413,7 @@ fn item_module(cx: &Context<'_>, item: &clean::Item, items: &[clean::Item]) -> i
 
             match myitem.kind {
                 clean::ExternCrateItem { ref src } => {
-                    use crate::html::format::anchor;
+                    use crate::html::format::print_anchor;
 
                     match *src {
                         Some(src) => {
@@ -421,7 +421,7 @@ fn item_module(cx: &Context<'_>, item: &clean::Item, items: &[clean::Item]) -> i
                                 w,
                                 "<dt><code>{}extern crate {} as {};",
                                 visibility_print_with_space(myitem, cx),
-                                anchor(myitem.item_id.expect_def_id(), src, cx),
+                                print_anchor(myitem.item_id.expect_def_id(), src, cx),
                                 EscapeBodyTextWithWbr(myitem.name.unwrap().as_str())
                             )?;
                         }
@@ -430,7 +430,11 @@ fn item_module(cx: &Context<'_>, item: &clean::Item, items: &[clean::Item]) -> i
                                 w,
                                 "<dt><code>{}extern crate {};",
                                 visibility_print_with_space(myitem, cx),
-                                anchor(myitem.item_id.expect_def_id(), myitem.name.unwrap(), cx)
+                                print_anchor(
+                                    myitem.item_id.expect_def_id(),
+                                    myitem.name.unwrap(),
+                                    cx
+                                )
                             )?;
                         }
                     }
@@ -439,7 +443,7 @@ fn item_module(cx: &Context<'_>, item: &clean::Item, items: &[clean::Item]) -> i
 
                 clean::ImportItem(ref import) => {
                     let stab_tags = import.source.did.map_or_else(String::new, |import_def_id| {
-                        extra_info_tags(tcx, myitem, item, Some(import_def_id)).to_string()
+                        print_extra_info_tags(tcx, myitem, item, Some(import_def_id)).to_string()
                     });
 
                     let id = match import.kind {
@@ -497,7 +501,9 @@ fn item_module(cx: &Context<'_>, item: &clean::Item, items: &[clean::Item]) -> i
                     write!(
                         w,
                         "<dt>\
-                            <a class=\"{class}\" href=\"{href}\" title=\"{title}\">{name}</a>\
+                            <a class=\"{class}\" href=\"{href}\" title=\"{title1} {title2}\">\
+                            {name}\
+                            </a>\
                             {visibility_and_hidden}\
                             {unsafety_flag}\
                             {stab_tags}\
@@ -505,11 +511,12 @@ fn item_module(cx: &Context<'_>, item: &clean::Item, items: &[clean::Item]) -> i
                         {docs_before}{docs}{docs_after}",
                         name = EscapeBodyTextWithWbr(myitem.name.unwrap().as_str()),
                         visibility_and_hidden = visibility_and_hidden,
-                        stab_tags = extra_info_tags(tcx, myitem, item, None),
+                        stab_tags = print_extra_info_tags(tcx, myitem, item, None),
                         class = myitem.type_(),
                         unsafety_flag = unsafety_flag,
-                        href = item_path(myitem.type_(), myitem.name.unwrap().as_str()),
-                        title = format_args!("{} {}", myitem.type_(), full_path(cx, myitem)),
+                        href = print_item_path(myitem.type_(), myitem.name.unwrap().as_str()),
+                        title1 = myitem.type_(),
+                        title2 = full_path(cx, myitem),
                     )?;
                 }
             }
@@ -524,7 +531,7 @@ fn item_module(cx: &Context<'_>, item: &clean::Item, items: &[clean::Item]) -> i
 
 /// Render the stability, deprecation and portability tags that are displayed in the item's summary
 /// at the module level.
-fn extra_info_tags(
+fn print_extra_info_tags(
     tcx: TyCtxt<'_>,
     item: &clean::Item,
     parent: &clean::Item,
@@ -639,7 +646,7 @@ fn item_function(cx: &Context<'_>, it: &clean::Item, f: &clean::Function) -> imp
 fn item_trait(cx: &Context<'_>, it: &clean::Item, t: &clean::Trait) -> impl fmt::Display {
     fmt::from_fn(|w| {
         let tcx = cx.tcx();
-        let bounds = bounds(&t.bounds, false, cx);
+        let bounds = print_bounds(&t.bounds, false, cx);
         let required_types =
             t.items.iter().filter(|m| m.is_required_associated_type()).collect::<Vec<_>>();
         let provided_types = t.items.iter().filter(|m| m.is_associated_type()).collect::<Vec<_>>();
@@ -652,7 +659,7 @@ fn item_trait(cx: &Context<'_>, it: &clean::Item, t: &clean::Trait) -> impl fmt:
         let count_types = required_types.len() + provided_types.len();
         let count_consts = required_consts.len() + provided_consts.len();
         let count_methods = required_methods.len() + provided_methods.len();
-        let must_implement_one_of_functions = tcx.trait_def(t.def_id).must_implement_one_of.clone();
+        let must_implement_one_of_functions = &tcx.trait_def(t.def_id).must_implement_one_of;
 
         // Output the trait definition
         wrap_item(w, |mut w| {
@@ -1088,7 +1095,7 @@ fn item_trait(cx: &Context<'_>, it: &clean::Item, t: &clean::Trait) -> impl fmt:
                             it,
                             &implementor_dups,
                             &collect_paths_for_type(
-                                implementor.inner_impl().for_.clone(),
+                                &implementor.inner_impl().for_,
                                 &cx.shared.cache,
                             ),
                         )
@@ -1236,7 +1243,7 @@ fn item_trait_alias(
                 attrs = render_attributes_in_pre(it, "", cx),
                 name = it.name.unwrap(),
                 generics = t.generics.print(cx),
-                bounds = bounds(&t.bounds, true, cx),
+                bounds = print_bounds(&t.bounds, true, cx),
                 where_clause =
                     print_where_clause(&t.generics, cx, 0, Ending::NoNewline).maybe_display(),
             )
@@ -2254,14 +2261,18 @@ pub(super) fn full_path(cx: &Context<'_>, item: &clean::Item) -> String {
     s
 }
 
-pub(super) fn item_path(ty: ItemType, name: &str) -> impl Display {
+pub(super) fn print_item_path(ty: ItemType, name: &str) -> impl Display {
     fmt::from_fn(move |f| match ty {
         ItemType::Module => write!(f, "{}index.html", ensure_trailing_slash(name)),
         _ => write!(f, "{ty}.{name}.html"),
     })
 }
 
-fn bounds(bounds: &[clean::GenericBound], trait_alias: bool, cx: &Context<'_>) -> impl Display {
+fn print_bounds(
+    bounds: &[clean::GenericBound],
+    trait_alias: bool,
+    cx: &Context<'_>,
+) -> impl Display {
     (!bounds.is_empty())
         .then_some(fmt::from_fn(move |f| {
             let has_lots_of_bounds = bounds.len() > 2;
diff --git a/src/librustdoc/html/render/write_shared.rs b/src/librustdoc/html/render/write_shared.rs
index 4f6e9abdbca..33738f7a242 100644
--- a/src/librustdoc/html/render/write_shared.rs
+++ b/src/librustdoc/html/render/write_shared.rs
@@ -607,16 +607,9 @@ impl TypeAliasPart {
         let cx = type_impl_collector.cx;
         let aliased_types = type_impl_collector.aliased_types;
         for aliased_type in aliased_types.values() {
-            let impls = aliased_type
-                .impl_
-                .values()
-                .flat_map(|AliasedTypeImpl { impl_, type_aliases }| {
-                    let mut ret: Vec<AliasSerializableImpl> = Vec::new();
-                    let trait_ = impl_
-                        .inner_impl()
-                        .trait_
-                        .as_ref()
-                        .map(|trait_| format!("{:#}", trait_.print(cx)));
+            let impls = aliased_type.impl_.values().filter_map(
+                |AliasedTypeImpl { impl_, type_aliases }| {
+                    let mut ret: Option<AliasSerializableImpl> = None;
                     // render_impl will filter out "impossible-to-call" methods
                     // to make that functionality work here, it needs to be called with
                     // each type alias, and if it gives a different result, split the impl
@@ -624,8 +617,8 @@ impl TypeAliasPart {
                         cx.id_map.borrow_mut().clear();
                         cx.deref_id_map.borrow_mut().clear();
                         let type_alias_fqp = (*type_alias_fqp).iter().join("::");
-                        if let Some(last) = ret.last_mut() {
-                            last.aliases.push(type_alias_fqp);
+                        if let Some(ret) = &mut ret {
+                            ret.aliases.push(type_alias_fqp);
                         } else {
                             let target_did = impl_
                                 .inner_impl()
@@ -660,16 +653,22 @@ impl TypeAliasPart {
                                 },
                             )
                             .to_string();
-                            ret.push(AliasSerializableImpl {
+                            // The alternate display prints it as plaintext instead of HTML.
+                            let trait_ = impl_
+                                .inner_impl()
+                                .trait_
+                                .as_ref()
+                                .map(|trait_| format!("{:#}", trait_.print(cx)));
+                            ret = Some(AliasSerializableImpl {
                                 text,
-                                trait_: trait_.clone(),
+                                trait_,
                                 aliases: vec![type_alias_fqp],
                             })
                         }
                     }
                     ret
-                })
-                .collect::<Vec<_>>();
+                },
+            );
 
             let mut path = PathBuf::from("type.impl");
             for component in &aliased_type.target_fqp[..aliased_type.target_fqp.len() - 1] {
@@ -682,7 +681,7 @@ impl TypeAliasPart {
             ));
 
             let part = OrderedJson::array_sorted(
-                impls.iter().map(OrderedJson::serialize).collect::<Result<Vec<_>, _>>().unwrap(),
+                impls.map(|impl_| OrderedJson::serialize(impl_).unwrap()),
             );
             path_parts.push(path, OrderedJson::array_unsorted([crate_name_json, &part]));
         }
@@ -760,7 +759,7 @@ impl TraitAliasPart {
                         Some(Implementor {
                             text: imp.inner_impl().print(false, cx).to_string(),
                             synthetic: imp.inner_impl().kind.is_auto(),
-                            types: collect_paths_for_type(imp.inner_impl().for_.clone(), cache),
+                            types: collect_paths_for_type(&imp.inner_impl().for_, cache),
                         })
                     }
                 })