From f9499ea9f55926bd53cd6897878a05f7982dc48f Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Wed, 26 May 2021 14:35:39 +0200
Subject: [PATCH 1/2] * Fix bug where some <details> tags were not closed. *
 Don't generate a <details> if there is no documentation

---
 src/librustdoc/html/render/print_item.rs | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/librustdoc/html/render/print_item.rs b/src/librustdoc/html/render/print_item.rs
index 50153ac14a204..e06168c708c18 100644
--- a/src/librustdoc/html/render/print_item.rs
+++ b/src/librustdoc/html/render/print_item.rs
@@ -578,14 +578,23 @@ fn item_trait(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, t: &clean::Tra
         info!("Documenting {} on {:?}", name, t.name);
         let item_type = m.type_();
         let id = cx.derive_id(format!("{}.{}", item_type, name));
-        write!(w, "<details class=\"rustdoc-toggle\" open><summary>");
-        write!(w, "<h3 id=\"{id}\" class=\"method\"><code>", id = id,);
+        let mut content = Buffer::empty_from(w);
+        document(&mut content, cx, m, Some(t));
+        let toggled = !content.is_empty();
+        if toggled {
+            write!(w, "<details class=\"rustdoc-toggle\" open><summary>");
+        }
+        write!(w, "<h3 id=\"{id}\" class=\"method\"><code>", id = id);
         render_assoc_item(w, m, AssocItemLink::Anchor(Some(&id)), ItemType::Impl, cx);
         w.write_str("</code>");
         render_stability_since(w, m, t, cx.tcx());
         write_srclink(cx, m, w);
-        w.write_str("</h3></summary>");
-        document(w, cx, m, Some(t));
+        w.write_str("</h3>");
+        if toggled {
+            write!(w, "</summary>");
+            w.push_buffer(content);
+            write!(w, "</details>");
+        }
     }
 
     if !types.is_empty() {

From 3bed0be9fc7cf77b56404db8291b227385e1550f Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Wed, 26 May 2021 14:36:58 +0200
Subject: [PATCH 2/2] Update trait toggle test

---
 src/test/rustdoc/toggle-trait-fn.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/test/rustdoc/toggle-trait-fn.rs b/src/test/rustdoc/toggle-trait-fn.rs
index a160809cbf957..7fcac78556b72 100644
--- a/src/test/rustdoc/toggle-trait-fn.rs
+++ b/src/test/rustdoc/toggle-trait-fn.rs
@@ -1,7 +1,11 @@
 #![crate_name = "foo"]
 
 // @has foo/trait.Foo.html
-// @has - '//details[@class="rustdoc-toggle"]//code' 'bar'
+// @!has - '//details[@class="rustdoc-toggle"]//code' 'bar'
+// @has - '//code' 'bar'
+// @has - '//details[@class="rustdoc-toggle"]//code' 'foo'
 pub trait Foo {
     fn bar() -> ();
+    /// hello
+    fn foo();
 }