rustdoc: show crate name beside small logo

This commit changes the layout to something a bit less "look at my logo!!!111"
gigantic, and makes it clearer where clicking the logo will actually take you.
It also means the crate name is persistently at the top of the sidebar, even
when in a sub-item page, and clicking that name takes you back to the root.

|         | Short crate name | Long crate name |
|---------|------------------|-----------------|
| Root    | ![short-root]    | ![long-root]
| Subpage | ![short-subpage] | ![long-subpage]

[short-root]: https://github.com/rust-lang/rust/assets/1593513/fe2ce102-d4b8-44e6-9f7b-68636a907f56
[short-subpage]: https://github.com/rust-lang/rust/assets/1593513/29501663-56c0-4151-b7de-d2637e167125
[long-root]: https://github.com/rust-lang/rust/assets/1593513/f6a385c0-b4c5-4a9c-954b-21b38de4192f
[long-subpage]: https://github.com/rust-lang/rust/assets/1593513/97ec47b4-61bf-4ebe-b461-0d2187b8c6ca

https://notriddle.com/rustdoc-html-demo-4/logo-lockup/image/index.html

https://notriddle.com/rustdoc-html-demo-4/logo-lockup/crossbeam_channel/index.html

https://notriddle.com/rustdoc-html-demo-4/logo-lockup/adler/struct.Adler32.html

https://notriddle.com/rustdoc-html-demo-4/logo-lockup/crossbeam_channel/struct.Sender.html

This improves visual information density (the construct with the logo and
crate name is *shorter* than the logo on its own, because it's not
square) and navigation clarity (we can now see what clicking the Rust logo
does, specifically).

Compare this with the layout at [Phoenix's Hexdocs] (which is what this
proposal is closely based on), the old proposal on [Internals Discourse]
(which always says "Rust standard library" in the sidebar, but doesn't do the
side-by-side layout).

[Phoenix's Hexdocs]: https://hexdocs.pm/phoenix/1.7.7/overview.html
[Internals Discourse]: https://internals.rust-lang.org/t/poc-of-a-new-design-for-the-generated-rustdoc/11018

In newer versions of rustdoc, the crate name and version are always shown in
the sidebar, even in subpages. Clicking the crate name does the same thing
clicking the logo always did: return you to the crate root.

While this actually takes up less screen real estate than the old layout on
desktop, it takes up more HTML. It's also a bit more visually complex.

I could do what the Internals POC did and keep the vertically stacked layout
all the time, instead of doing a horizontal stack where possible. It would
take up more screen real estate, though.

This design is lifted almost verbatim from Hexdocs. It seems to work for them.
[`opentelemetry_process_propagator`], for example, has a long application name.

[`opentelemetry_process_propagator`]: https://hexdocs.pm/opentelemetry_process_propagator/OpentelemetryProcessPropagator.html

Has anyone written the rationale on why the Rust logo shows up on projects that
aren't the standard library? If we turned it off on non-standard crates by
default, it would line wrap crate names a lot less often.

Or maybe we should encourage crate authors to include their own logo more
often? It certainly helps give people a better sense of "place."

I'm not sure of anything that directly follows up this one. Plenty of other
changes could be made to improve the layout, like

* coming up with a less cluttered way to do disclosure (there's a lot of `[-]`
  on the page)
* doing a better job of separating lateral navigation (vec::Vec links to
  vec::IntoIter) and the table of contents (vec::Vec links to vec::Vec::new)
* giving readers more control of how much rustdoc hows them, and giving doc
  authors more control of how much it generates
* better search that reduces the need to browse

But those are mostly orthogonal, not future possibilities unlocked by this change.

13 files changed, 95 insertions, 48 deletions

diff --git a/src/librustdoc/html/layout.rs b/src/librustdoc/html/layout.rs
index 8c5871d9126..25ca67db649 100644
--- a/src/librustdoc/html/layout.rs
+++ b/src/librustdoc/html/layout.rs
@@ -17,6 +17,7 @@ pub(crate) struct Layout {
     pub(crate) external_html: ExternalHtml,
     pub(crate) default_settings: FxHashMap<String, String>,
     pub(crate) krate: String,
+    pub(crate) krate_version: String,
     /// The given user css file which allow to customize the generated
     /// documentation theme.
     pub(crate) css_file_extension: Option<PathBuf>,
diff --git a/src/librustdoc/html/render/context.rs b/src/librustdoc/html/render/context.rs
index 97714afaa45..62c7dbe78ec 100644
--- a/src/librustdoc/html/render/context.rs
+++ b/src/librustdoc/html/render/context.rs
@@ -534,6 +534,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
             external_html,
             default_settings,
             krate: krate.name(tcx).to_string(),
+            krate_version: cache.crate_version.as_deref().unwrap_or_default().to_string(),
             css_file_extension: extension_css,
             scrape_examples_extension: !call_locations.is_empty(),
         };
@@ -669,10 +670,9 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
 
         let blocks = sidebar_module_like(all.item_sections());
         let bar = Sidebar {
-            title_prefix: "Crate ",
-            title: crate_name.as_str(),
+            title_prefix: "",
+            title: "",
             is_crate: false,
-            version: "",
             blocks: vec![blocks],
             path: String::new(),
         };
diff --git a/src/librustdoc/html/render/sidebar.rs b/src/librustdoc/html/render/sidebar.rs
index 76f63c6f63e..417c572fd77 100644
--- a/src/librustdoc/html/render/sidebar.rs
+++ b/src/librustdoc/html/render/sidebar.rs
@@ -19,7 +19,6 @@ pub(super) struct Sidebar<'a> {
     pub(super) title_prefix: &'static str,
     pub(super) title: &'a str,
     pub(super) is_crate: bool,
-    pub(super) version: &'a str,
     pub(super) blocks: Vec<LinkBlock<'a>>,
     pub(super) path: String,
 }
@@ -99,12 +98,12 @@ pub(super) fn print_sidebar(cx: &Context<'_>, it: &clean::Item, buffer: &mut Buf
         || it.is_primitive()
         || it.is_union()
         || it.is_enum()
-        || it.is_mod()
+        // crate title is displayed as part of logo lockup
+        || (it.is_mod() && !it.is_crate())
         || it.is_type_alias()
     {
         (
             match *it.kind {
-                clean::ModuleItem(..) if it.is_crate() => "Crate ",
                 clean::ModuleItem(..) => "Module ",
                 _ => "",
             },
@@ -113,14 +112,12 @@ pub(super) fn print_sidebar(cx: &Context<'_>, it: &clean::Item, buffer: &mut Buf
     } else {
         ("", "")
     };
-    let version =
-        if it.is_crate() { cx.cache().crate_version.as_deref().unwrap_or_default() } else { "" };
     let path: String = if !it.is_mod() {
         cx.current.iter().map(|s| s.as_str()).intersperse("::").collect()
     } else {
         "".into()
     };
-    let sidebar = Sidebar { title_prefix, title, is_crate: it.is_crate(), version, blocks, path };
+    let sidebar = Sidebar { title_prefix, title, is_crate: it.is_crate(), blocks, path };
     sidebar.render_into(buffer).unwrap();
 }
 
diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index 47f9e650281..6a6747affb2 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -461,19 +461,9 @@ img {
 	display: none !important;
 }
 
-.sidebar .logo-container {
-	margin-top: 10px;
-	margin-bottom: 10px;
-	text-align: center;
-}
-
-.version {
-	overflow-wrap: break-word;
-}
-
 .logo-container > img {
-	height: 100px;
-	width: 100px;
+	height: 48px;
+	width: 48px;
 }
 
 ul.block, .block li {
@@ -510,6 +500,8 @@ ul.block, .block li {
 	color: var(--sidebar-link-color);
 }
 .sidebar .current,
+.sidebar .current a,
+.sidebar-crate a.logo-container:hover + h2 a,
 .sidebar a:hover:not(.logo-container) {
 	background-color: var(--sidebar-current-link-background-color);
 }
@@ -524,6 +516,47 @@ ul.block, .block li {
 	overflow: hidden;
 }
 
+.sidebar-crate {
+	display: flex;
+	align-items: center;
+	justify-content: center;
+	margin: 0 32px;
+	column-gap: 32px;
+	flex-wrap: wrap;
+}
+
+.sidebar-crate h2 {
+	flex-grow: 1;
+	/* This setup with the margins and row-gap is designed to make flex-wrap
+		work the way we want. If they're in the side-by-side lockup, there
+		should be a 16px margin to the left of the logo (visually the same as
+		the 24px one on everything else, which are not giant circles) and 8px
+		between it and the crate's name and version. When they're line wrapped,
+		the logo needs to have the same margin on both sides of itself (to
+		center properly) and the crate name and version need 24px on their
+		left margin. */
+	margin: 0 -8px;
+}
+
+.sidebar-crate .logo-container {
+	margin: 10px -16px;
+	text-align: center;
+}
+
+.sidebar-crate h2 a {
+	display: block;
+	margin-left: -0.25rem;
+	padding-left: 0.25rem;
+	margin-right: -24px;
+}
+
+.sidebar-crate h2 .version {
+	display: block;
+	font-weight: normal;
+	font-size: 1rem;
+	overflow-wrap: break-word;
+}
+
 .mobile-topbar {
 	display: none;
 }
diff --git a/src/librustdoc/html/static/js/main.js b/src/librustdoc/html/static/js/main.js
index eb256455b08..5e852af2196 100644
--- a/src/librustdoc/html/static/js/main.js
+++ b/src/librustdoc/html/static/js/main.js
@@ -51,9 +51,13 @@ function setMobileTopbar() {
     // but with the current code it's hard to get the right information in the right place.
     const mobileTopbar = document.querySelector(".mobile-topbar");
     const locationTitle = document.querySelector(".sidebar h2.location");
-    if (mobileTopbar && locationTitle) {
+    if (mobileLocationTitle) {
         const mobileTitle = document.createElement("h2");
-        mobileTitle.innerHTML = locationTitle.innerHTML;
+        if (hasClass(document.body, "crate")) {
+            mobileLocationTitle.innerText = `Crate ${window.currentCrate}`;
+        } else if (locationTitle) {
+            mobileLocationTitle.innerHTML = locationTitle.innerHTML;
+        }
         mobileTopbar.appendChild(mobileTitle);
     }
 }
diff --git a/src/librustdoc/html/templates/page.html b/src/librustdoc/html/templates/page.html
index 579c782be09..0987010b940 100644
--- a/src/librustdoc/html/templates/page.html
+++ b/src/librustdoc/html/templates/page.html
@@ -88,13 +88,21 @@
     {% endif %}
     <nav class="sidebar"> {# #}
         {% if page.css_class != "src" %}
-        <a class="logo-container" href="{{page.root_path|safe}}{{krate_with_trailing_slash|safe}}index.html"> {# #}
-            {% if !layout.logo.is_empty() %}
-                <img src="{{layout.logo}}" alt="logo"> {# #}
-            {% else %}
-                <img class="rust-logo" src="{{static_root_path|safe}}{{files.rust_logo_svg}}" alt="logo"> {# #}
-            {% endif %}
-        </a> {# #}
+        <div class="sidebar-crate">
+            <a class="logo-container" href="{{page.root_path|safe}}{{krate_with_trailing_slash|safe}}index.html"> {# #}
+                {% if !layout.logo.is_empty() %}
+                    <img src="{{layout.logo}}" alt="logo"> {# #}
+                {% else %}
+                    <img class="rust-logo" src="{{static_root_path|safe}}{{files.rust_logo_svg}}" alt="logo"> {# #}
+                {% endif %}
+            </a> {# #}
+            <h2> {# #}
+                <a href="{{page.root_path|safe}}{{krate_with_trailing_slash|safe}}index.html">{{layout.krate}}</a> {# #}
+                {% if !layout.krate_version.is_empty() %}
+                    <span class="version">{{+ layout.krate_version}}</span>
+                {% endif %}
+            </h2>
+        </div>
         {% endif %}
         {{ sidebar|safe }}
     </nav> {# #}
diff --git a/src/librustdoc/html/templates/sidebar.html b/src/librustdoc/html/templates/sidebar.html
index 01d476ad29f..14a61f3643e 100644
--- a/src/librustdoc/html/templates/sidebar.html
+++ b/src/librustdoc/html/templates/sidebar.html
@@ -6,9 +6,6 @@
 <div class="sidebar-elems">
     {% if is_crate %}
         <ul class="block">
-            {% if !version.is_empty() %}
-                <li class="version">Version {{+ version}}</li>
-            {% endif %}
             <li><a id="all-types" href="all.html">All Items</a></li> {# #}
         </ul>
     {% endif %}
diff --git a/tests/rustdoc-gui/huge-logo.goml b/tests/rustdoc-gui/huge-logo.goml
index 6d3eb66068c..bfc24c3260d 100644
--- a/tests/rustdoc-gui/huge-logo.goml
+++ b/tests/rustdoc-gui/huge-logo.goml
@@ -4,8 +4,8 @@ go-to: "file://" + |DOC_PATH| + "/huge_logo/index.html"
 
 set-window-size: (1280, 1024)
 // offsetWidth = width of sidebar
-assert-property: (".sidebar .logo-container", {"offsetWidth": "200", "offsetHeight": 100})
-assert-property: (".sidebar .logo-container img", {"offsetWidth": "100", "offsetHeight": 100})
+assert-property: (".sidebar-crate .logo-container", {"offsetWidth": "48", "offsetHeight": 48})
+assert-property: (".sidebar-crate .logo-container img", {"offsetWidth": "48", "offsetHeight": 48})
 
 set-window-size: (400, 600)
 // offset = size + margin
diff --git a/tests/rustdoc-gui/sidebar-mobile.goml b/tests/rustdoc-gui/sidebar-mobile.goml
index 4b8337ace3a..beff07b555d 100644
--- a/tests/rustdoc-gui/sidebar-mobile.goml
+++ b/tests/rustdoc-gui/sidebar-mobile.goml
@@ -50,7 +50,7 @@ assert-position: ("#method\.must_use", {"y": 46})
 // Check that the bottom-most item on the sidebar menu can be scrolled fully into view.
 click: ".sidebar-menu-toggle"
 scroll-to: ".block.keyword li:nth-child(1)"
-compare-elements-position-near: (".block.keyword li:nth-child(1)", ".mobile-topbar", {"y": 543.19})
+compare-elements-position-near: (".block.keyword li:nth-child(1)", ".mobile-topbar", {"y": 544})
 
 // Now checking the background color of the sidebar.
 show-text: true
diff --git a/tests/rustdoc-gui/sidebar.goml b/tests/rustdoc-gui/sidebar.goml
index 520481d3bba..7050ee902a5 100644
--- a/tests/rustdoc-gui/sidebar.goml
+++ b/tests/rustdoc-gui/sidebar.goml
@@ -50,9 +50,9 @@ set-local-storage: {"rustdoc-theme": "light"}
 // We reload the page so the local storage settings are being used.
 reload:
 
-assert-text: (".sidebar > .location", "Crate test_docs")
-// In modules, we only have one "location" element.
-assert-count: (".sidebar .location", 1)
+assert-text: (".sidebar > .sidebar-crate > h2 > a", "test_docs")
+// Crate root has no "location" element
+assert-count: (".sidebar .location", 0)
 assert-count: (".sidebar h2", 1)
 assert-text: ("#all-types", "All Items")
 assert-css: ("#all-types", {"color": "#356da4"})
@@ -74,8 +74,9 @@ assert-text: ("#structs + .item-table .item-name > a", "Foo")
 click: "#structs + .item-table .item-name > a"
 
 // PAGE: struct.Foo.html
+assert-count: (".sidebar .sidebar-crate", 1)
 assert-count: (".sidebar .location", 1)
-assert-count: (".sidebar h2", 2)
+assert-count: (".sidebar h2", 3)
 // We check that there is no crate listed outside of the top level.
 assert-false: ".sidebar-elems > .crate"
 
@@ -94,7 +95,8 @@ click: ".sidebar-elems ul.crate > li:first-child > a"
 // PAGE: lib2/index.html
 go-to: "file://" + |DOC_PATH| + "/lib2/index.html"
 assert-property: (".sidebar", {"clientWidth": "200"})
-assert-text: (".sidebar > .location", "Crate lib2")
+assert-text: (".sidebar > .sidebar-crate > h2 > a", "lib2")
+assert-count: (".sidebar .location", 0)
 // We check that we have the crates list and that the "current" on is now "lib2".
 assert-text: (".sidebar-elems ul.crate > li > a.current", "lib2")
 // We now go to the "foobar" function page.
@@ -108,21 +110,25 @@ click: "#functions + .item-table .item-name > a"
 
 // PAGE: fn.foobar.html
 // In items containing no items (like functions or constants) and in modules, we have no
-// "location" elements. Only the parent module h2.
+// "location" elements. Only the parent module h2 and crate.
+assert-text: (".sidebar > .sidebar-crate > h2 > a", "lib2")
 assert-count: (".sidebar .location", 0)
-assert-count: (".sidebar h2", 1)
+assert-count: (".sidebar h2", 2)
 assert-text: (".sidebar .sidebar-elems h2", "In lib2")
 // We check that we don't have the crate list.
 assert-false: ".sidebar-elems > .crate"
 
 go-to: "./module/index.html"
 assert-property: (".sidebar", {"clientWidth": "200"})
+assert-text: (".sidebar > .sidebar-crate > h2 > a", "lib2")
 assert-text: (".sidebar > .location", "Module module")
+assert-count: (".sidebar .location", 1)
 // We check that we don't have the crate list.
 assert-false: ".sidebar-elems > .crate"
 
 go-to: "./sub_module/sub_sub_module/index.html"
 assert-property: (".sidebar", {"clientWidth": "200"})
+assert-text: (".sidebar > .sidebar-crate > h2 > a", "lib2")
 assert-text: (".sidebar > .location", "Module sub_sub_module")
 // We check that we don't have the crate list.
 assert-false: ".sidebar-elems .crate"
@@ -152,14 +158,14 @@ assert-property: (".sidebar", {"clientWidth": "200"})
 
 // Checks that all.html and index.html have their sidebar link in the same place.
 go-to: "file://" + |DOC_PATH| + "/test_docs/index.html"
-store-property: (".sidebar .location a", {
+store-property: (".sidebar .sidebar-crate h2 a", {
     "clientWidth": index_sidebar_width,
     "clientHeight": index_sidebar_height,
     "offsetTop": index_sidebar_y,
     "offsetLeft": index_sidebar_x,
 })
 go-to: "file://" + |DOC_PATH| + "/test_docs/all.html"
-assert-property: (".sidebar .location a", {
+assert-property: (".sidebar .sidebar-crate h2 a", {
     "clientWidth": |index_sidebar_width|,
     "clientHeight": |index_sidebar_height|,
     "offsetTop": |index_sidebar_y|,
diff --git a/tests/rustdoc/crate-version-escape.rs b/tests/rustdoc/crate-version-escape.rs
index 8413709f15e..f134d9baa7d 100644
--- a/tests/rustdoc/crate-version-escape.rs
+++ b/tests/rustdoc/crate-version-escape.rs
@@ -2,4 +2,4 @@
 
 #![crate_name = "foo"]
 
-// @has 'foo/index.html' '//li[@class="version"]' 'Version <script>alert("hi")</script>'
+// @has 'foo/index.html' '//*[@class="version"]' '<script>alert("hi")</script>'
diff --git a/tests/rustdoc/crate-version.rs b/tests/rustdoc/crate-version.rs
index 2592c98530f..d4be845b71e 100644
--- a/tests/rustdoc/crate-version.rs
+++ b/tests/rustdoc/crate-version.rs
@@ -1,3 +1,3 @@
 // compile-flags: --crate-version=1.3.37
 
-// @has 'crate_version/index.html' '//*[@class="version"]' 'Version 1.3.37'
+// @has 'crate_version/index.html' '//*[@class="version"]' '1.3.37'
diff --git a/tests/rustdoc/titles.rs b/tests/rustdoc/titles.rs
index f6a059de620..f9da5a81375 100644
--- a/tests/rustdoc/titles.rs
+++ b/tests/rustdoc/titles.rs
@@ -2,7 +2,8 @@
 #![feature(rustc_attrs)]
 
 // @matches 'foo/index.html' '//h1' 'Crate foo'
-// @matches 'foo/index.html' '//h2[@class="location"]' 'Crate foo'
+// @matches 'foo/index.html' '//div[@class="sidebar-crate"]/h2/a' 'foo'
+// @count 'foo/index.html' '//h2[@class="location"]' 0
 
 // @matches 'foo/foo_mod/index.html' '//h1' 'Module foo::foo_mod'
 // @matches 'foo/foo_mod/index.html' '//h2[@class="location"]' 'Module foo_mod'