rustdoc: use details tag for trait implementors

This switches from JS-generated toggles to using the HTML <details> tag
for expanding and collapsing entries in the "Implementors" section.

Author: jsha

src/librustdoc/html/render/mod.rs

@@ -1313,6 +1313,7 @@ fn render_impl(
     let cache = cx.cache();
     let traits = &cache.traits;
     let trait_ = i.trait_did_full(cache).map(|did| &traits[&did]);
+    let mut close_tags = String::new();
 
     if render_mode == RenderMode::Normal {
         let id = cx.derive_id(match i.inner_impl().trait_ {
@@ -1331,7 +1332,12 @@ fn render_impl(
             format!(" aliases=\"{}\"", aliases.join(","))
         };
         if let Some(use_absolute) = use_absolute {
-            write!(w, "<h3 id=\"{}\" class=\"impl\"{}><code class=\"in-band\">", id, aliases);
+            write!(
+                w,
+                "<details class=\"rustdoc-toggle implementors-toggle\"><summary><h3 id=\"{}\" class=\"impl\"{}><code class=\"in-band\">",
+                id, aliases
+            );
+            close_tags.insert_str(0, "</details>");
             write!(w, "{}", i.inner_impl().print(use_absolute, cx));
             if show_def_docs {
                 for it in &i.inner_impl().items {
@@ -1354,11 +1360,12 @@ fn render_impl(
         } else {
             write!(
                 w,
-                "<h3 id=\"{}\" class=\"impl\"{}><code class=\"in-band\">{}</code>",
+                "<details class=\"rustdoc-toggle implementors-toggle\"><summary><h3 id=\"{}\" class=\"impl\"{}><code class=\"in-band\">{}</code>",
                 id,
                 aliases,
                 i.inner_impl().print(false, cx)
             );
+            close_tags.insert_str(0, "</details>");
         }
         write!(w, "<a href=\"#{}\" class=\"anchor\"></a>", id);
         render_stability_since_raw(
@@ -1370,6 +1377,7 @@ fn render_impl(
         );
         write_srclink(cx, &i.impl_item, w);
         w.write_str("</h3>");
+        w.write_str("</summary>");
 
         if trait_.is_some() {
             if let Some(portability) = portability(&i.impl_item, Some(parent)) {
@@ -1580,6 +1588,7 @@ fn render_impl(
     }
 
     w.write_str("<div class=\"impl-items\">");
+    close_tags.insert_str(0, "</div>");
     for trait_item in &i.inner_impl().items {
         doc_impl_item(
             w,
@@ -1650,7 +1659,7 @@ fn render_impl(
             );
         }
     }
-    w.write_str("</div>");
+    w.write_str(&close_tags);
 }
 
 fn print_sidebar(cx: &Context<'_>, it: &clean::Item, buffer: &mut Buffer) {

src/librustdoc/html/static/main.js

@@ -1196,31 +1196,18 @@ function hideThemeButtonState() {
             if (!next) {
                 return;
             }
-            if (hasClass(e, "impl") &&
-                (next.getElementsByClassName("method").length > 0 ||
-                 next.getElementsByClassName("associatedconstant").length > 0)) {
-                var newToggle = toggle.cloneNode(true);
-                insertAfter(newToggle, e.childNodes[e.childNodes.length - 1]);
-                // In case the option "auto-collapse implementors" is not set to false, we collapse
-                // all implementors.
-                if (hideImplementors === true && e.parentNode.id === "implementors-list") {
-                    collapseDocs(newToggle, "hide");
-                }
-            }
         };
 
         onEachLazy(document.getElementsByClassName("method"), func);
         onEachLazy(document.getElementsByClassName("associatedconstant"), func);
-        onEachLazy(document.getElementsByClassName("impl"), funcImpl);
         var impl_call = function() {};
-        // Large items are hidden by default in the HTML. If the setting overrides that, show 'em.
-        if (!hideLargeItemContents) {
-            onEachLazy(document.getElementsByTagName("details"), function (e) {
-                if (hasClass(e, "type-contents-toggle")) {
-                    e.open = true;
-                }
-            });
-        }
+        onEachLazy(document.getElementsByTagName("details"), function (e) {
+            var showLargeItem = !hideLargeItemContents && hasClass(e, "type-contents-toggle");
+            var showImplementor = !hideImplementors && hasClass(e, "implementors-toggle");
+            if (showLargeItem || showImplementor) {
+                e.open = true;
+            }
+        });
         if (hideMethodDocs === true) {
             impl_call = function(e, newToggle) {
                 if (e.id.match(/^impl(?:-\d+)?$/) === null) {

src/librustdoc/html/static/rustdoc.css

@@ -1561,6 +1561,10 @@ h4 > .notable-traits {
 		left: -10px;
 	}
 
+	.item-list > details.rustdoc-toggle > summary:not(.hideme)::before {
+		left: -10px;
+	}
+
 	#all-types {
 		margin: 10px;
 	}
@@ -1775,14 +1779,16 @@ details.rustdoc-toggle > summary::before {
 	font-weight: 300;
 	font-size: 0.8em;
 	letter-spacing: 1px;
+	cursor: pointer;
 }
 
 details.rustdoc-toggle > summary.hideme::before {
 	position: relative;
 }
 
 details.rustdoc-toggle > summary:not(.hideme)::before {
-	float: left;
+	position: absolute;
+	left: -23px;
 }
 
 /* When a "hideme" summary is open and the "Expand description" or "Show

src/test/rustdoc/const-generics/add-impl.rs

@@ -8,7 +8,7 @@ pub struct Simd<T, const WIDTH: usize> {
     inner: T,
 }
 
-// @has foo/struct.Simd.html '//div[@id="trait-implementations-list"]/h3/code' 'impl Add<Simd<u8, 16_usize>> for Simd<u8, 16>'
+// @has foo/struct.Simd.html '//div[@id="trait-implementations-list"]//h3/code' 'impl Add<Simd<u8, 16_usize>> for Simd<u8, 16>'
 impl Add for Simd<u8, 16> {
     type Output = Self;
 

src/test/rustdoc/duplicate_impls/issue-33054.rs

@@ -1,8 +1,8 @@
 // @has issue_33054/impls/struct.Foo.html
 // @has - '//code' 'impl Foo'
 // @has - '//code' 'impl Bar for Foo'
-// @count - '//*[@id="trait-implementations-list"]/*[@class="impl"]' 1
-// @count - '//*[@id="main"]/*[@class="impl"]' 1
+// @count - '//*[@id="trait-implementations-list"]//*[@class="impl"]' 1
+// @count - '//*[@id="main"]/details/summary/*[@class="impl"]' 1
 // @has issue_33054/impls/bar/trait.Bar.html
 // @has - '//code' 'impl Bar for Foo'
 // @count - '//*[@class="struct"]' 1

src/test/rustdoc/issue-21474.rs

@@ -7,5 +7,5 @@ mod inner {
 pub trait Blah { }
 
 // @count issue_21474/struct.What.html \
-//        '//*[@id="trait-implementations-list"]/*[@class="impl"]' 1
+//        '//*[@id="trait-implementations-list"]//*[@class="impl"]' 1
 pub struct What;

src/test/rustdoc/issue-29503.rs

@@ -5,7 +5,7 @@ pub trait MyTrait {
     fn my_string(&self) -> String;
 }
 
-// @has - "//div[@id='implementors-list']/h3[@id='impl-MyTrait']//code" "impl<T> MyTrait for T where T: Debug"
+// @has - "//div[@id='implementors-list']//h3[@id='impl-MyTrait']//code" "impl<T> MyTrait for T where T: Debug"
 impl<T> MyTrait for T where T: fmt::Debug {
     fn my_string(&self) -> String {
         format!("{:?}", self)

src/test/rustdoc/issue-45584.rs

@@ -4,12 +4,12 @@ pub trait Bar<T, U> {}
 
 // @has 'foo/struct.Foo1.html'
 pub struct Foo1;
-// @count - '//*[@id="trait-implementations-list"]/*[@class="impl"]' 1
+// @count - '//*[@id="trait-implementations-list"]//*[@class="impl"]' 1
 // @has - '//*[@class="impl"]' "impl Bar<Foo1, &'static Foo1> for Foo1"
 impl Bar<Foo1, &'static Foo1> for Foo1 {}
 
 // @has 'foo/struct.Foo2.html'
 pub struct Foo2;
-// @count - '//*[@id="trait-implementations-list"]/*[@class="impl"]' 1
+// @count - '//*[@id="trait-implementations-list"]//*[@class="impl"]' 1
 // @has - '//*[@class="impl"]' "impl Bar<&'static Foo2, Foo2> for u8"
 impl Bar<&'static Foo2, Foo2> for u8 {}

src/test/rustdoc/issue-50159.rs

@@ -13,8 +13,8 @@ impl<B, C> Signal2 for B where B: Signal<Item = C> {
 // @has issue_50159/struct.Switch.html
 // @has - '//code' 'impl<B> Send for Switch<B> where <B as Signal>::Item: Send'
 // @has - '//code' 'impl<B> Sync for Switch<B> where <B as Signal>::Item: Sync'
-// @count - '//*[@id="implementations-list"]/*[@class="impl"]' 0
-// @count - '//*[@id="synthetic-implementations-list"]/*[@class="impl"]' 5
+// @count - '//*[@id="implementations-list"]//*[@class="impl"]' 0
+// @count - '//*[@id="synthetic-implementations-list"]//*[@class="impl"]' 5
 pub struct Switch<B: Signal> {
     pub inner: <B as Signal2>::Item2,
 }

src/test/rustdoc/issue-51236.rs

@@ -7,7 +7,7 @@ pub mod traits {
 }
 
 // @has issue_51236/struct.Owned.html
-// @has - '//*[@id="synthetic-implementations-list"]/*[@class="impl"]//code' "impl<T> Send for \
+// @has - '//*[@id="synthetic-implementations-list"]//*[@class="impl"]//code' "impl<T> Send for \
 // Owned<T> where <T as Owned<'static>>::Reader: Send"
 pub struct Owned<T> where T: for<'a> ::traits::Owned<'a> {
     marker: PhantomData<<T as ::traits::Owned<'static>>::Reader>,