Print only blanket implementations on reference primitive type

src/librustdoc/html/render/mod.rs

@@ -616,7 +616,7 @@ fn short_item_info(
 pub(crate) fn render_impls(
     cx: &mut Context<'_>,
     w: &mut Buffer,
-    impls: &[&&Impl],
+    impls: &[&Impl],
     containing_item: &clean::Item,
     toggle_open_by_default: bool,
 ) {
@@ -1039,9 +1039,9 @@ pub(crate) fn render_all_impls(
     w: &mut Buffer,
     cx: &mut Context<'_>,
     containing_item: &clean::Item,
-    concrete: &[&&Impl],
+    concrete: &[&Impl],
-    synthetic: &[&&Impl],
+    synthetic: &[&Impl],
-    blanket_impl: &[&&Impl],
+    blanket_impl: &[&Impl],
 ) {
     let mut impls = Buffer::empty_from(w);
     render_impls(cx, &mut impls, concrete, containing_item, true);
@@ -1158,9 +1158,9 @@ fn render_assoc_items_inner(
             return;
         }
 
-        let (synthetic, concrete): (Vec<&&Impl>, Vec<&&Impl>) =
+        let (synthetic, concrete): (Vec<&Impl>, Vec<&Impl>) =
-            traits.iter().partition(|t| t.inner_impl().kind.is_auto());
+            traits.into_iter().partition(|t| t.inner_impl().kind.is_auto());
-        let (blanket_impl, concrete): (Vec<&&Impl>, _) =
+        let (blanket_impl, concrete): (Vec<&Impl>, _) =
             concrete.into_iter().partition(|t| t.inner_impl().kind.is_blanket());
 
         render_all_impls(w, cx, containing_item, &concrete, &synthetic, &blanket_impl);
@@ -1968,6 +1968,70 @@ fn small_url_encode(s: String) -> String {
     }
 }
 
+pub(crate) fn sidebar_render_assoc_items(
+    cx: &Context<'_>,
+    out: &mut Buffer,
+    id_map: &mut IdMap,
+    concrete: Vec<&Impl>,
+    synthetic: Vec<&Impl>,
+    blanket_impl: Vec<&Impl>,
+) {
+    let format_impls = |impls: Vec<&Impl>, id_map: &mut IdMap| {
+        let mut links = FxHashSet::default();
+
+        let mut ret = impls
+            .iter()
+            .filter_map(|it| {
+                let trait_ = it.inner_impl().trait_.as_ref()?;
+                let encoded =
+                    id_map.derive(get_id_for_impl(&it.inner_impl().for_, Some(trait_), cx));
+
+                let i_display = format!("{:#}", trait_.print(cx));
+                let out = Escape(&i_display);
+                let prefix = match it.inner_impl().polarity {
+                    ty::ImplPolarity::Positive | ty::ImplPolarity::Reservation => "",
+                    ty::ImplPolarity::Negative => "!",
+                };
+                let generated = format!("<a href=\"#{}\">{}{}</a>", encoded, prefix, out);
+                if links.insert(generated.clone()) { Some(generated) } else { None }
+            })
+            .collect::<Vec<String>>();
+        ret.sort();
+        ret
+    };
+
+    let concrete_format = format_impls(concrete, id_map);
+    let synthetic_format = format_impls(synthetic, id_map);
+    let blanket_format = format_impls(blanket_impl, id_map);
+
+    if !concrete_format.is_empty() {
+        print_sidebar_block(
+            out,
+            "trait-implementations",
+            "Trait Implementations",
+            concrete_format.iter(),
+        );
+    }
+
+    if !synthetic_format.is_empty() {
+        print_sidebar_block(
+            out,
+            "synthetic-implementations",
+            "Auto Trait Implementations",
+            synthetic_format.iter(),
+        );
+    }
+
+    if !blanket_format.is_empty() {
+        print_sidebar_block(
+            out,
+            "blanket-implementations",
+            "Blanket Implementations",
+            blanket_format.iter(),
+        );
+    }
+}
+
 fn sidebar_assoc_items(cx: &Context<'_>, out: &mut Buffer, it: &clean::Item) {
     let did = it.item_id.expect_def_id();
     let cache = cx.cache();
@@ -2016,65 +2080,12 @@ fn sidebar_assoc_items(cx: &Context<'_>, out: &mut Buffer, it: &clean::Item) {
                 sidebar_deref_methods(cx, out, impl_, v, &mut derefs, &mut used_links);
             }
 
-            let format_impls = |impls: Vec<&Impl>, id_map: &mut IdMap| {
-                let mut links = FxHashSet::default();
-
-                let mut ret = impls
-                    .iter()
-                    .filter_map(|it| {
-                        let trait_ = it.inner_impl().trait_.as_ref()?;
-                        let encoded =
-                            id_map.derive(get_id_for_impl(&it.inner_impl().for_, Some(trait_), cx));
-
-                        let i_display = format!("{:#}", trait_.print(cx));
-                        let out = Escape(&i_display);
-                        let prefix = match it.inner_impl().polarity {
-                            ty::ImplPolarity::Positive | ty::ImplPolarity::Reservation => "",
-                            ty::ImplPolarity::Negative => "!",
-                        };
-                        let generated = format!("<a href=\"#{}\">{}{}</a>", encoded, prefix, out);
-                        if links.insert(generated.clone()) { Some(generated) } else { None }
-                    })
-                    .collect::<Vec<String>>();
-                ret.sort();
-                ret
-            };
-
             let (synthetic, concrete): (Vec<&Impl>, Vec<&Impl>) =
                 v.iter().partition::<Vec<_>, _>(|i| i.inner_impl().kind.is_auto());
             let (blanket_impl, concrete): (Vec<&Impl>, Vec<&Impl>) =
                 concrete.into_iter().partition::<Vec<_>, _>(|i| i.inner_impl().kind.is_blanket());
 
-            let concrete_format = format_impls(concrete, &mut id_map);
+            sidebar_render_assoc_items(cx, out, &mut id_map, concrete, synthetic, blanket_impl);
-            let synthetic_format = format_impls(synthetic, &mut id_map);
-            let blanket_format = format_impls(blanket_impl, &mut id_map);
-
-            if !concrete_format.is_empty() {
-                print_sidebar_block(
-                    out,
-                    "trait-implementations",
-                    "Trait Implementations",
-                    concrete_format.iter(),
-                );
-            }
-
-            if !synthetic_format.is_empty() {
-                print_sidebar_block(
-                    out,
-                    "synthetic-implementations",
-                    "Auto Trait Implementations",
-                    synthetic_format.iter(),
-                );
-            }
-
-            if !blanket_format.is_empty() {
-                print_sidebar_block(
-                    out,
-                    "blanket-implementations",
-                    "Blanket Implementations",
-                    blanket_format.iter(),
-                );
-            }
         }
     }
 }
@@ -2344,9 +2355,54 @@ fn sidebar_trait(cx: &Context<'_>, buf: &mut Buffer, it: &clean::Item, t: &clean
     buf.push_str("</section>")
 }
 
+/// Returns the list of implementations for the primitive reference type, filtering out any
+/// implementations that are on concrete or partially generic types, only keeping implementations
+/// of the form `impl<T> Trait for &T`.
+pub(crate) fn get_filtered_impls_for_reference<'a>(
+    shared: &'a Rc<SharedContext<'_>>,
+    it: &clean::Item,
+) -> (Vec<&'a Impl>, Vec<&'a Impl>, Vec<&'a Impl>) {
+    let def_id = it.item_id.expect_def_id();
+    // If the reference primitive is somehow not defined, exit early.
+    let Some(v) = shared.cache.impls.get(&def_id) else { return (Vec::new(), Vec::new(), Vec::new()) };
+    // Since there is no "direct implementation" on the reference primitive type, we filter out
+    // every implementation which isn't a trait implementation.
+    let traits: Vec<_> = v.iter().filter(|i| i.inner_impl().trait_.is_some()).collect();
+    let (synthetic, concrete): (Vec<&Impl>, Vec<&Impl>) =
+        traits.into_iter().partition(|t| t.inner_impl().kind.is_auto());
+
+    let (blanket_impl, concrete): (Vec<&Impl>, _) =
+        concrete.into_iter().partition(|t| t.inner_impl().kind.is_blanket());
+    // Now we keep only references over full generic types.
+    let concrete: Vec<_> = concrete
+        .into_iter()
+        .filter(|t| match t.inner_impl().for_ {
+            clean::Type::BorrowedRef { ref type_, .. } => type_.is_full_generic(),
+            _ => false,
+        })
+        .collect();
+
+    (concrete, synthetic, blanket_impl)
+}
+
 fn sidebar_primitive(cx: &Context<'_>, buf: &mut Buffer, it: &clean::Item) {
     let mut sidebar = Buffer::new();
-    sidebar_assoc_items(cx, &mut sidebar, it);
+
+    if it.name.map(|n| n.as_str() != "reference").unwrap_or(false) {
+        sidebar_assoc_items(cx, &mut sidebar, it);
+    } else {
+        let shared = Rc::clone(&cx.shared);
+        let (concrete, synthetic, blanket_impl) = get_filtered_impls_for_reference(&shared, it);
+
+        sidebar_render_assoc_items(
+            cx,
+            &mut sidebar,
+            &mut IdMap::new(),
+            concrete,
+            synthetic,
+            blanket_impl,
+        );
+    }
 
     if !sidebar.is_empty() {
         write!(buf, "<section>{}</section>", sidebar.into_inner());

src/librustdoc/html/render/print_item.rs

@@ -16,10 +16,10 @@ use std::fmt;
 use std::rc::Rc;
 
 use super::{
-    collect_paths_for_type, document, ensure_trailing_slash, item_ty_to_section,
+    collect_paths_for_type, document, ensure_trailing_slash, get_filtered_impls_for_reference,
-    notable_traits_decl, render_assoc_item, render_assoc_items, render_attributes_in_code,
+    item_ty_to_section, notable_traits_decl, render_all_impls, render_assoc_item,
-    render_attributes_in_pre, render_impl, render_rightside, render_stability_since_raw,
+    render_assoc_items, render_attributes_in_code, render_attributes_in_pre, render_impl,
-    AssocItemLink, Context, ImplRenderingParameters,
+    render_rightside, render_stability_since_raw, AssocItemLink, Context, ImplRenderingParameters,
 };
 use crate::clean;
 use crate::config::ModuleSorting;
@@ -1371,8 +1371,18 @@ fn item_proc_macro(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, m: &c
 }
 
 fn item_primitive(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item) {
+    let def_id = it.item_id.expect_def_id();
     document(w, cx, it, None, HeadingOffset::H2);
-    render_assoc_items(w, cx, it, it.item_id.expect_def_id(), AssocItemRender::All)
+    if it.name.map(|n| n.as_str() != "reference").unwrap_or(false) {
+        render_assoc_items(w, cx, it, def_id, AssocItemRender::All);
+    } else {
+        // We handle the "reference" primitive type on its own because we only want to list
+        // implementations on generic types.
+        let shared = Rc::clone(&cx.shared);
+        let (concrete, synthetic, blanket_impl) = get_filtered_impls_for_reference(&shared, it);
+
+        render_all_impls(w, cx, it, &concrete, &synthetic, &blanket_impl);
+    }
 }
 
 fn item_constant(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, c: &clean::Constant) {