Rollup merge of #88964 - GuillaumeGomez:version-help, r=Nemo157

Add rustdoc version into the help popup

After a discussion with a rustdoc user about a specific behaviour, we realized we were not talking about the same version. To add on top of it, it was actually not that simple to find out the version since it was hosted documentation.

So to simplify things, I added the version into the help popup:

![Screenshot from 2021-09-16 10-45-52](https://user-images.githubusercontent.com/3050060/133581128-b93b460a-e1cb-4a31-9f2f-97c7a916cfcc.png)

Does the version format looks or would you prefer that I add more information? We can also add the commit hash, commit date, host and release.

cc `@rust-lang/rustdoc`
r? `@jyn514`

6 files changed, 39 insertions, 13 deletions

diff --git a/src/librustdoc/html/render/write_shared.rs b/src/librustdoc/html/render/write_shared.rs
index 1dd0917699b..c1a83ad5820 100644
--- a/src/librustdoc/html/render/write_shared.rs
+++ b/src/librustdoc/html/render/write_shared.rs
@@ -268,10 +268,18 @@ pub(super) fn write_shared(
     // Maybe we can change the representation to move this out of main.js?
     write_minify(
         "main.js",
-        static_files::MAIN_JS.replace(
-            "/* INSERT THEMES HERE */",
-            &format!(" = {}", serde_json::to_string(&themes).unwrap()),
-        ),
+        static_files::MAIN_JS
+            .replace(
+                "/* INSERT THEMES HERE */",
+                &format!(" = {}", serde_json::to_string(&themes).unwrap()),
+            )
+            .replace(
+                "/* INSERT RUSTDOC_VERSION HERE */",
+                &format!(
+                    "rustdoc {}",
+                    rustc_interface::util::version_str().unwrap_or("unknown version")
+                ),
+            ),
         cx,
         options,
     )?;
diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index 2d4bfc62af6..eb7cc9309f4 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -928,15 +928,24 @@ body.blur > :not(#help) {
 	display: block;
 	margin-right: 0.5rem;
 }
-#help > div > span {
+#help span.top, #help span.bottom {
 	text-align: center;
 	display: block;
-	margin: 10px 0;
 	font-size: 18px;
-	border-bottom: 1px solid #ccc;
+
+}
+#help span.top {
+	text-align: center;
+	display: block;
+	margin: 10px 0;
+	border-bottom: 1px solid;
 	padding-bottom: 4px;
 	margin-bottom: 6px;
 }
+#help span.bottom {
+	clear: both;
+	border-top: 1px solid;
+}
 #help dd { margin: 5px 35px; }
 #help .infos { padding-left: 0; }
 #help h1, #help h2 { margin-top: 0; }
diff --git a/src/librustdoc/html/static/css/themes/ayu.css b/src/librustdoc/html/static/css/themes/ayu.css
index eada8f4a04d..c79801e8308 100644
--- a/src/librustdoc/html/static/css/themes/ayu.css
+++ b/src/librustdoc/html/static/css/themes/ayu.css
@@ -286,8 +286,8 @@ details.undocumented > summary::before {
 	border-radius: 4px;
 }
 
-#help > div > span {
-	border-bottom-color: #5c6773;
+#help span.bottom, #help span.top {
+	border-color: #5c6773;
 }
 
 .since {
diff --git a/src/librustdoc/html/static/css/themes/dark.css b/src/librustdoc/html/static/css/themes/dark.css
index d9348be6994..d2e54070acd 100644
--- a/src/librustdoc/html/static/css/themes/dark.css
+++ b/src/librustdoc/html/static/css/themes/dark.css
@@ -242,8 +242,8 @@ details.undocumented > summary::before {
 	border-color: #bfbfbf;
 }
 
-#help > div > span {
-	border-bottom-color: #bfbfbf;
+#help span.bottom, #help span.top {
+	border-color: #bfbfbf;
 }
 
 #help dt {
diff --git a/src/librustdoc/html/static/css/themes/light.css b/src/librustdoc/html/static/css/themes/light.css
index 0ffe5929ea5..25d810560c1 100644
--- a/src/librustdoc/html/static/css/themes/light.css
+++ b/src/librustdoc/html/static/css/themes/light.css
@@ -232,8 +232,8 @@ details.undocumented > summary::before {
 	border-color: #bfbfbf;
 }
 
-#help > div > span {
-	border-bottom-color: #bfbfbf;
+#help span.bottom, #help span.top {
+	border-color: #bfbfbf;
 }
 
 .since {
diff --git a/src/librustdoc/html/static/js/main.js b/src/librustdoc/html/static/js/main.js
index 1eebd392564..e396fd9d288 100644
--- a/src/librustdoc/html/static/js/main.js
+++ b/src/librustdoc/html/static/js/main.js
@@ -911,6 +911,7 @@ function hideThemeButtonState() {
         });
 
         var book_info = document.createElement("span");
+        book_info.className = "top";
         book_info.innerHTML = "You can find more information in \
             <a href=\"https://doc.rust-lang.org/rustdoc/\">the rustdoc book</a>.";
 
@@ -961,6 +962,14 @@ function hideThemeButtonState() {
         container.appendChild(div_shortcuts);
         container.appendChild(div_infos);
 
+        var rustdoc_version = document.createElement("span");
+        rustdoc_version.className = "bottom";
+        var rustdoc_version_code = document.createElement("code");
+        rustdoc_version_code.innerText = "/* INSERT RUSTDOC_VERSION HERE */";
+        rustdoc_version.appendChild(rustdoc_version_code);
+
+        container.appendChild(rustdoc_version);
+
         popup.appendChild(container);
         insertAfter(popup, searchState.outputElement());
         // So that it's only built once and then it'll do nothing when called!