rustdoc: use javascript to layout notable traits popups

Fixes #102576

src/librustdoc/html/format.rs

@@ -107,10 +107,6 @@ impl Buffer {
         self.buffer
     }
 
-    pub(crate) fn insert_str(&mut self, idx: usize, s: &str) {
-        self.buffer.insert_str(idx, s);
-    }
-
     pub(crate) fn push_str(&mut self, s: &str) {
         self.buffer.push_str(s);
     }

src/librustdoc/html/render/context.rs

@@ -69,11 +69,13 @@ pub(crate) struct Context<'tcx> {
     /// the source files are present in the html rendering, then this will be
     /// `true`.
     pub(crate) include_sources: bool,
+    /// Collection of all types with notable traits referenced in the current module.
+    pub(crate) types_with_notable_traits: FxHashSet<clean::Type>,
 }
 
 // `Context` is cloned a lot, so we don't want the size to grow unexpectedly.
 #[cfg(all(not(windows), target_arch = "x86_64", target_pointer_width = "64"))]
-rustc_data_structures::static_assert_size!(Context<'_>, 128);
+rustc_data_structures::static_assert_size!(Context<'_>, 160);
 
 /// Shared mutable state used in [`Context`] and elsewhere.
 pub(crate) struct SharedContext<'tcx> {
@@ -532,6 +534,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
             deref_id_map: FxHashMap::default(),
             shared: Rc::new(scx),
             include_sources,
+            types_with_notable_traits: FxHashSet::default(),
         };
 
         if emit_crate {
@@ -560,6 +563,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
             id_map: IdMap::new(),
             shared: Rc::clone(&self.shared),
             include_sources: self.include_sources,
+            types_with_notable_traits: FxHashSet::default(),
         }
     }
 
@@ -803,6 +807,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
                 }
             }
         }
+
         Ok(())
     }
 

src/librustdoc/html/render/mod.rs

@@ -59,7 +59,7 @@ use rustc_span::{
     symbol::{sym, Symbol},
     BytePos, FileName, RealFileName,
 };
-use serde::ser::SerializeSeq;
+use serde::ser::{SerializeMap, SerializeSeq};
 use serde::{Serialize, Serializer};
 
 use crate::clean::{self, ItemId, RenderedLink, SelfTy};
@@ -803,7 +803,7 @@ fn assoc_method(
     d: &clean::FnDecl,
     link: AssocItemLink<'_>,
     parent: ItemType,
-    cx: &Context<'_>,
+    cx: &mut Context<'_>,
     render_mode: RenderMode,
 ) {
     let tcx = cx.tcx();
@@ -836,6 +836,8 @@ fn assoc_method(
         + name.as_str().len()
         + generics_len;
 
+    let notable_traits = d.output.as_return().and_then(|output| notable_traits_button(output, cx));
+
     let (indent, indent_str, end_newline) = if parent == ItemType::Trait {
         header_len += 4;
         let indent_str = "    ";
@@ -861,13 +863,9 @@ fn assoc_method(
         name = name,
         generics = g.print(cx),
         decl = d.full_print(header_len, indent, cx),
-        notable_traits = d
-            .output
-            .as_return()
-            .and_then(|output| notable_traits_decl(output, cx))
-            .unwrap_or_default(),
+        notable_traits = notable_traits.unwrap_or_default(),
         where_clause = print_where_clause(g, cx, indent, end_newline),
-    )
+    );
 }
 
 /// Writes a span containing the versions at which an item became stable and/or const-stable. For
@@ -967,7 +965,7 @@ fn render_assoc_item(
     item: &clean::Item,
     link: AssocItemLink<'_>,
     parent: ItemType,
-    cx: &Context<'_>,
+    cx: &mut Context<'_>,
     render_mode: RenderMode,
 ) {
     match &*item.kind {
@@ -1277,8 +1275,8 @@ fn should_render_item(item: &clean::Item, deref_mut_: bool, tcx: TyCtxt<'_>) ->
     }
 }
 
-fn notable_traits_decl(ty: &clean::Type, cx: &Context<'_>) -> Option<String> {
-    let mut out = Buffer::html();
+pub(crate) fn notable_traits_button(ty: &clean::Type, cx: &mut Context<'_>) -> Option<String> {
+    let mut has_notable_trait = false;
 
     let did = ty.def_id(cx.cache())?;
 
@@ -1291,6 +1289,7 @@ fn notable_traits_decl(ty: &clean::Type, cx: &Context<'_>) -> Option<String> {
     {
         return None;
     }
+
     if let Some(impls) = cx.cache().impls.get(&did) {
         for i in impls {
             let impl_ = i.inner_impl();
@@ -1304,56 +1303,106 @@ fn notable_traits_decl(ty: &clean::Type, cx: &Context<'_>) -> Option<String> {
 
                 if cx.cache().traits.get(&trait_did).map_or(false, |t| t.is_notable_trait(cx.tcx()))
                 {
-                    if out.is_empty() {
-                        write!(
-                            &mut out,
-                            "<span class=\"notable\">Notable traits for {}</span>\
-                         <code class=\"content\">",
-                            impl_.for_.print(cx)
-                        );
-                    }
+                    has_notable_trait = true;
+                }
+            }
+        }
+    }
+
+    if has_notable_trait {
+        cx.types_with_notable_traits.insert(ty.clone());
+        Some(format!(
+            "<span class=\"notable-traits\" data-ty=\"{ty:#}\">\
+                <span class=\"notable-traits-tooltip\">ⓘ</span>\
+            </span>",
+            ty = ty.print(cx),
+        ))
+    } else {
+        None
+    }
+}
+
+fn notable_traits_decl(ty: &clean::Type, cx: &Context<'_>) -> (String, String) {
+    let mut out = Buffer::html();
+
+    let did = ty.def_id(cx.cache()).expect("notable_traits_button already checked this");
 
-                    //use the "where" class here to make it small
+    let impls = cx.cache().impls.get(&did).expect("notable_traits_button already checked this");
+
+    for i in impls {
+        let impl_ = i.inner_impl();
+        if !impl_.for_.without_borrowed_ref().is_same(ty.without_borrowed_ref(), cx.cache()) {
+            // Two different types might have the same did,
+            // without actually being the same.
+            continue;
+        }
+        if let Some(trait_) = &impl_.trait_ {
+            let trait_did = trait_.def_id();
+
+            if cx.cache().traits.get(&trait_did).map_or(false, |t| t.is_notable_trait(cx.tcx())) {
+                if out.is_empty() {
                     write!(
                         &mut out,
-                        "<span class=\"where fmt-newline\">{}</span>",
-                        impl_.print(false, cx)
+                        "<h3 class=\"notable\">Notable traits for <code>{}</code></h3>\
+                     <pre class=\"content\"><code>",
+                        impl_.for_.print(cx)
                     );
-                    for it in &impl_.items {
-                        if let clean::AssocTypeItem(ref tydef, ref _bounds) = *it.kind {
-                            out.push_str("<span class=\"where fmt-newline\">    ");
-                            let empty_set = FxHashSet::default();
-                            let src_link = AssocItemLink::GotoSource(trait_did.into(), &empty_set);
-                            assoc_type(
-                                &mut out,
-                                it,
-                                &tydef.generics,
-                                &[], // intentionally leaving out bounds
-                                Some(&tydef.type_),
-                                src_link,
-                                0,
-                                cx,
-                            );
-                            out.push_str(";</span>");
-                        }
+                }
+
+                //use the "where" class here to make it small
+                write!(
+                    &mut out,
+                    "<span class=\"where fmt-newline\">{}</span>",
+                    impl_.print(false, cx)
+                );
+                for it in &impl_.items {
+                    if let clean::AssocTypeItem(ref tydef, ref _bounds) = *it.kind {
+                        out.push_str("<span class=\"where fmt-newline\">    ");
+                        let empty_set = FxHashSet::default();
+                        let src_link = AssocItemLink::GotoSource(trait_did.into(), &empty_set);
+                        assoc_type(
+                            &mut out,
+                            it,
+                            &tydef.generics,
+                            &[], // intentionally leaving out bounds
+                            Some(&tydef.type_),
+                            src_link,
+                            0,
+                            cx,
+                        );
+                        out.push_str(";</span>");
                     }
                 }
             }
         }
     }
-
     if out.is_empty() {
-        return None;
+        write!(&mut out, "</code></pre>",);
     }
 
-    out.insert_str(
-        0,
-        "<span class=\"notable-traits\"><span class=\"notable-traits-tooltip\">ⓘ\
-        <span class=\"notable-traits-tooltiptext\"><span class=\"docblock\">",
-    );
-    out.push_str("</code></span></span></span></span>");
+    (format!("{:#}", ty.print(cx)), out.into_inner())
+}
 
-    Some(out.into_inner())
+pub(crate) fn notable_traits_json<'a>(
+    tys: impl Iterator<Item = &'a clean::Type>,
+    cx: &Context<'_>,
+) -> String {
+    let mp: Vec<(String, String)> = tys.map(|ty| notable_traits_decl(ty, cx)).collect();
+    struct NotableTraitsMap(Vec<(String, String)>);
+    impl Serialize for NotableTraitsMap {
+        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where
+            S: Serializer,
+        {
+            let mut map = serializer.serialize_map(Some(self.0.len()))?;
+            for item in &self.0 {
+                map.serialize_entry(&item.0, &item.1)?;
+            }
+            map.end()
+        }
+    }
+    serde_json::to_string(&NotableTraitsMap(mp))
+        .expect("serialize (string, string) -> json object cannot fail")
 }
 
 #[derive(Clone, Copy, Debug)]

src/librustdoc/html/render/print_item.rs

@@ -17,9 +17,10 @@ use std::rc::Rc;
 
 use super::{
     collect_paths_for_type, document, ensure_trailing_slash, get_filtered_impls_for_reference,
-    item_ty_to_section, notable_traits_decl, render_all_impls, render_assoc_item,
-    render_assoc_items, render_attributes_in_code, render_attributes_in_pre, render_impl,
-    render_rightside, render_stability_since_raw, AssocItemLink, Context, ImplRenderingParameters,
+    item_ty_to_section, notable_traits_button, notable_traits_json, render_all_impls,
+    render_assoc_item, render_assoc_items, render_attributes_in_code, render_attributes_in_pre,
+    render_impl, render_rightside, render_stability_since_raw, AssocItemLink, Context,
+    ImplRenderingParameters,
 };
 use crate::clean;
 use crate::config::ModuleSorting;
@@ -183,6 +184,16 @@ pub(super) fn print_item(
             unreachable!();
         }
     }
+
+    // Render notable-traits.js used for all methods in this module.
+    if !cx.types_with_notable_traits.is_empty() {
+        write!(
+            buf,
+            r#"<script type="text/json" id="notable-traits-data">{}</script>"#,
+            notable_traits_json(cx.types_with_notable_traits.iter(), cx)
+        );
+        cx.types_with_notable_traits.clear();
+    }
 }
 
 /// For large structs, enums, unions, etc, determine whether to hide their fields
@@ -516,6 +527,9 @@ fn item_function(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, f: &cle
         + name.as_str().len()
         + generics_len;
 
+    let notable_traits =
+        f.decl.output.as_return().and_then(|output| notable_traits_button(output, cx));
+
     wrap_into_item_decl(w, |w| {
         wrap_item(w, "fn", |w| {
             render_attributes_in_pre(w, it, "");
@@ -533,16 +547,11 @@ fn item_function(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, f: &cle
                 generics = f.generics.print(cx),
                 where_clause = print_where_clause(&f.generics, cx, 0, Ending::Newline),
                 decl = f.decl.full_print(header_len, 0, cx),
-                notable_traits = f
-                    .decl
-                    .output
-                    .as_return()
-                    .and_then(|output| notable_traits_decl(output, cx))
-                    .unwrap_or_default(),
+                notable_traits = notable_traits.unwrap_or_default(),
             );
         });
     });
-    document(w, cx, it, None, HeadingOffset::H2)
+    document(w, cx, it, None, HeadingOffset::H2);
 }
 
 fn item_trait(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, t: &clean::Trait) {

src/librustdoc/html/static/css/noscript.css

@@ -22,3 +22,9 @@ nav.sub {
 .source .sidebar {
 	display: none;
 }
+
+.notable-traits {
+	/* layout requires javascript
+	    https://github.com/rust-lang/rust/issues/102576 */
+	display: none;
+}

src/librustdoc/html/static/css/rustdoc.css

@@ -183,6 +183,8 @@ h4.code-header {
 	font-weight: 600;
 	margin: 0;
 	padding: 0;
+	/* position notable traits in mobile mode within the header */
+	position: relative;
 }
 
 #crate-search,
@@ -1268,13 +1270,12 @@ h3.variant {
 	cursor: pointer;
 }
 
-.notable-traits:hover .notable-traits-tooltiptext,
-.notable-traits .notable-traits-tooltiptext.force-tooltip {
+.notable-traits .notable-traits-tooltiptext {
 	display: inline-block;
+	visibility: hidden;
 }
 
-.notable-traits .notable-traits-tooltiptext {
-	display: none;
+.notable-traits-tooltiptext {
 	padding: 5px 3px 3px 3px;
 	border-radius: 6px;
 	margin-left: 5px;
@@ -1292,22 +1293,26 @@ h3.variant {
 	content: "\00a0\00a0\00a0";
 }
 
-.notable-traits .docblock {
+.notable-traits-tooltiptext .docblock {
 	margin: 0;
 }
 
-.notable-traits .notable {
-	margin: 0;
-	margin-bottom: 13px;
+.notable-traits-tooltiptext .notable {
 	font-size: 1.1875rem;
 	font-weight: 600;
 	display: block;
 }
 
-.notable-traits .docblock code.content {
+.notable-traits-tooltiptext pre, .notable-traits-tooltiptext code {
+	background: transparent;
+}
+
+.notable-traits-tooltiptext .docblock pre.content {
 	margin: 0;
 	padding: 0;
 	font-size: 1.25rem;
+	white-space: pre-wrap;
+	overflow: hidden;
 }
 
 .search-failed {