From 655798558e2ba9801fc055a536a59dbbffa23c88 Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume.gomez@huawei.com>
Date: Sat, 21 May 2022 13:57:52 +0200
Subject: [PATCH 1/3] Improve display of `<details>` in doc blocks

---
 src/librustdoc/html/static/css/rustdoc.css | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index d0229bdb5f23c..ed22a1a353e46 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -158,8 +158,8 @@ h1.fqn {
 	Underlines elsewhere in the documentation break up visual flow and tend to invert
 	section hierarchies. */
 h2,
-.top-doc h3,
-.top-doc h4 {
+.top-doc .docblock > h3,
+.top-doc .docblock > h4 {
 	border-bottom: 1px solid;
 }
 h3.code-header {
@@ -1669,6 +1669,18 @@ details.rustdoc-toggle[open] > summary.hideme::after {
 	content: "Collapse";
 }
 
+.docblock details summary {
+	display: flex;
+	list-style: none;
+	align-items: center;
+}
+.docblock details[open] summary::before {
+	content: "► ";
+}
+.docblock details[open] summary::before {
+	content: "▼ ";
+}
+
 /* Media Queries */
 
 @media (min-width: 701px) {

From 07596fefc114335c5f4c8cc3ed5b7361b17cf91b Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume.gomez@huawei.com>
Date: Sat, 21 May 2022 15:05:19 +0200
Subject: [PATCH 2/3] Fix display of `<details>`/`<summary>` in doc blocks

---
 src/librustdoc/html/static/css/rustdoc.css | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index ed22a1a353e46..c7e1330e86acf 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -1669,16 +1669,9 @@ details.rustdoc-toggle[open] > summary.hideme::after {
 	content: "Collapse";
 }
 
-.docblock details summary {
-	display: flex;
-	list-style: none;
-	align-items: center;
-}
-.docblock details[open] summary::before {
-	content: "► ";
-}
-.docblock details[open] summary::before {
-	content: "▼ ";
+/* This is needed in docblocks to have the "▶" element to be on the same line. */
+.docblock summary > * {
+	display: inline-block;
 }
 
 /* Media Queries */

From b8db8cc10f5d3a28d75f89680f2734e24cd1490c Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume.gomez@huawei.com>
Date: Sat, 21 May 2022 15:05:56 +0200
Subject: [PATCH 3/3] Add GUI test for `<details>`/`<summary>` display

---
 src/test/rustdoc-gui/docblock-details.goml | 23 ++++++++++++++++++++++
 src/test/rustdoc-gui/src/test_docs/lib.rs  | 12 +++++++++++
 2 files changed, 35 insertions(+)
 create mode 100644 src/test/rustdoc-gui/docblock-details.goml

diff --git a/src/test/rustdoc-gui/docblock-details.goml b/src/test/rustdoc-gui/docblock-details.goml
new file mode 100644
index 0000000000000..2edbf1e4e2d8c
--- /dev/null
+++ b/src/test/rustdoc-gui/docblock-details.goml
@@ -0,0 +1,23 @@
+// This ensures that the `<details>`/`<summary>` elements are displayed as expected.
+goto: file://|DOC_PATH|/test_docs/details/struct.Details.html
+show-text: true
+local-storage: {"rustdoc-theme": "dark", "rustdoc-use-system-theme": "false"}
+reload:
+
+// We first check that the headers in the `.top-doc` doc block still have their
+// bottom border.
+assert-text: (".top-doc .docblock > h3", "Hello")
+assert-css: (
+    ".top-doc .docblock > h3",
+    {"border-bottom": "1px solid rgb(221, 221, 221)"},
+)
+// We now check that the `<summary>` doesn't have a bottom border and has the correct display.
+assert-css: (
+    ".top-doc .docblock summary h4",
+    {"border-bottom": "0px none rgb(221, 221, 221)"},
+)
+// This allows to ensure that summary is on one line only!
+assert-property: (".top-doc .docblock summary h4", {"offsetHeight": "33"})
+assert-css: (".top-doc .docblock summary h4", {"margin-top": "15px", "margin-bottom": "5px"})
+// So `33 + 15 + 5` == `53`
+assert-property: (".top-doc .docblock summary", {"offsetHeight": "53"})
diff --git a/src/test/rustdoc-gui/src/test_docs/lib.rs b/src/test/rustdoc-gui/src/test_docs/lib.rs
index b6fe9eb2565bd..aa2f78289bea2 100644
--- a/src/test/rustdoc-gui/src/test_docs/lib.rs
+++ b/src/test/rustdoc-gui/src/test_docs/lib.rs
@@ -277,3 +277,15 @@ pub use macros::*;
 
 #[doc(alias = "AliasForTheStdReexport")]
 pub use ::std as TheStdReexport;
+
+pub mod details {
+    /// We check the appearance of the `<details>`/`<summary>` in here.
+    ///
+    /// ## Hello
+    ///
+    /// <details>
+    /// <summary><h4>I'm a summary</h4></summary>
+    /// <div>I'm the content of the details!</div>
+    /// </details>
+    pub struct Details;
+}