rustdoc: clean up the In [name] up-pointer

This commit makes three changes for consistency and readability:

  - It shows the sibling navigation on module pages. It's weird
    that it didn't work before, and is inconsistent with everything
    else (even Crates have sibling navigation with other Crates).
  - It hides the "In [parent]" header if it's the same as the
    current crate, and if there's no other header between them.
    We need to keep it on modules and types, since they have
    their own header and data between them, and we don't want
    to show siblings under a header implying that they're children.
  - It adds a margin to deal with the headers butting directly into
    the branding lockup.

src/librustdoc/html/render/context.rs

@@ -662,7 +662,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
         let shared = Rc::clone(&self.shared);
         let mut page = layout::Page {
             title: "List of all items in this crate",
-            css_class: "mod",
+            css_class: "mod sys",
             root_path: "../",
             static_root_path: shared.static_root_path.as_deref(),
             description: "List of all items in this crate",
@@ -677,6 +677,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
             title_prefix: "",
             title: "",
             is_crate: false,
+            is_mod: false,
             blocks: vec![blocks],
             path: String::new(),
         };

src/librustdoc/html/render/sidebar.rs

@@ -19,6 +19,7 @@ pub(super) struct Sidebar<'a> {
     pub(super) title_prefix: &'static str,
     pub(super) title: &'a str,
     pub(super) is_crate: bool,
+    pub(super) is_mod: bool,
     pub(super) blocks: Vec<LinkBlock<'a>>,
     pub(super) path: String,
 }
@@ -112,12 +113,24 @@ pub(super) fn print_sidebar(cx: &Context<'_>, it: &clean::Item, buffer: &mut Buf
     } else {
         ("", "")
     };
-    let path: String = if !it.is_mod() {
-        cx.current.iter().map(|s| s.as_str()).intersperse("::").collect()
+    // need to show parent path header if:
+    //   - it's a child module, instead of the crate root
+    //   - there's a sidebar section for the item itself
+    //
+    // otherwise, the parent path header is redundant with the big crate
+    // branding area at the top of the sidebar
+    let sidebar_path = if it.is_mod() { &cx.current[..cx.current.len() - 1] } else { &cx.current[..] };
+    let path: String = if sidebar_path.len() > 1 || !title.is_empty() {
+        let path = sidebar_path.iter().map(|s| s.as_str()).intersperse("::").collect();
+        if sidebar_path.len() == 1 {
+            format!("crate {path}")
+        } else {
+            path
+        }
     } else {
         "".into()
     };
-    let sidebar = Sidebar { title_prefix, title, is_crate: it.is_crate(), blocks, path };
+    let sidebar = Sidebar { title_prefix, title, is_mod: it.is_mod(), is_crate: it.is_crate(), blocks, path };
     sidebar.render_into(buffer).unwrap();
 }
 

src/librustdoc/html/render/write_shared.rs

@@ -336,7 +336,7 @@ if (typeof exports !== 'undefined') {exports.searchIndex = searchIndex};
             let dst = cx.dst.join("index.html");
             let page = layout::Page {
                 title: "Index of crates",
-                css_class: "mod",
+                css_class: "mod sys",
                 root_path: "./",
                 static_root_path: shared.static_root_path.as_deref(),
                 description: "List of crates",

src/librustdoc/html/static/css/rustdoc.css

@@ -523,7 +523,7 @@ ul.block, .block li {
 	justify-content: center;
 	/* there's a 10px padding at the top of <main>, and a 4px margin at the
 		top of the search form. To line them up, add them. */
-	margin: 14px 32px 0;
+	margin: 14px 32px 1rem;
 	row-gap: 10px;
 	column-gap: 32px;
 	flex-wrap: wrap;

src/librustdoc/html/static/js/main.js

@@ -457,22 +457,27 @@ function preLoadCss(cssUrl) {
                 return;
             }
 
+            const modpath = hasClass(document.body, "mod") ? "../" : "";
+
             const h3 = document.createElement("h3");
-            h3.innerHTML = `<a href="index.html#${id}">${longty}</a>`;
+            h3.innerHTML = `<a href="${modpath}index.html#${id}">${longty}</a>`;
             const ul = document.createElement("ul");
             ul.className = "block " + shortty;
 
             for (const name of filtered) {
                 let path;
                 if (shortty === "mod") {
-                    path = name + "/index.html";
+                    path = `${modpath}${name}/index.html`;
                 } else {
-                    path = shortty + "." + name + ".html";
+                    path = `${modpath}${shortty}.${name}.html`;
+                }
+                let current_page = document.location.href.toString();
+                if (current_page.endsWith("/")) {
+                    current_page += "index.html";
                 }
-                const current_page = document.location.href.split("/").pop();
                 const link = document.createElement("a");
                 link.href = path;
-                if (path === current_page) {
+                if (link.href === current_page) {
                     link.className = "current";
                 }
                 link.textContent = name;

src/librustdoc/html/templates/page.html

@@ -42,6 +42,8 @@
     <script defer src="{{page.root_path|safe}}src-files{{page.resource_suffix}}.js"></script> {# #}
     {% else if !page.css_class.contains("mod") %}
     <script defer src="sidebar-items{{page.resource_suffix}}.js"></script> {# #}
+    {% else if !page.css_class.contains("sys") %}
+    <script defer src="../sidebar-items{{page.resource_suffix}}.js"></script> {# #}
     {% endif %}
     <script defer src="{{static_root_path|safe}}{{files.main_js}}"></script> {# #}
     {% if layout.scrape_examples_extension %}

src/librustdoc/html/templates/sidebar.html

@@ -29,6 +29,6 @@
         </section>
     {% endif %}
     {% if !path.is_empty() %}
-        <h2><a href="index.html">In {{+ path}}</a></h2>
+        <h2><a href="{% if is_mod %}../{% endif %}index.html">In {{+ path}}</a></h2>
     {% endif %}
 </div>

tests/rustdoc-gui/sidebar-mobile.goml

@@ -26,7 +26,7 @@ assert-css: (".sidebar", {"left": "0px"})
 // Make sure the "struct Foo" header is hidden, since the mobile topbar already does it.
 assert-css: ("//nav[contains(@class, 'sidebar')]//h2/a[text()='Foo']/parent::h2", {"display": "none"})
 // Make sure the global navigation is still here.
-assert-css: ("//nav[contains(@class, 'sidebar')]//h2/a[text()='In test_docs']/parent::h2", {"display": "block"})
+assert-css: ("//nav[contains(@class, 'sidebar')]//h2/a[text()='In crate test_docs']/parent::h2", {"display": "block"})
 
 // Click elsewhere.
 click: "body"

tests/rustdoc-gui/sidebar.goml

@@ -110,11 +110,11 @@ 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 and crate.
+// "location" elements. Only the crate and optional parent module.
+// This page, being directly below the crate, only has its heading.
 assert-text: (".sidebar > .sidebar-crate > h2 > a", "lib2")
 assert-count: (".sidebar .location", 0)
-assert-count: (".sidebar h2", 2)
-assert-text: (".sidebar .sidebar-elems h2", "In lib2")
+assert-count: (".sidebar h2", 1)
 // We check that we don't have the crate list.
 assert-false: ".sidebar-elems > .crate"
 
@@ -123,6 +123,15 @@ assert-property: (".sidebar", {"clientWidth": "200"})
 assert-text: (".sidebar > .sidebar-crate > h2 > a", "lib2")
 assert-text: (".sidebar > .location", "Module module")
 assert-count: (".sidebar .location", 1)
+// Module page requires three headings:
+//   - Presistent crate branding (name and version)
+//   - Module name, followed by TOC for module headings
+//   - "In crate [name]" parent pointer, followed by sibling navigation
+assert-count: (".sidebar h2", 3)
+assert-text: (".sidebar > .sidebar-elems > h2", "In crate lib2")
+assert-property: (".sidebar > .sidebar-elems > h2 > a", {
+    "href": "/lib2/index.html",
+}, ENDS_WITH)
 // We check that we don't have the crate list.
 assert-false: ".sidebar-elems > .crate"
 
@@ -130,6 +139,10 @@ 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")
+assert-text: (".sidebar > .sidebar-elems > h2", "In lib2::module::sub_module")
+assert-property: (".sidebar > .sidebar-elems > h2 > a", {
+    "href": "/module/sub_module/index.html",
+}, ENDS_WITH)
 // We check that we don't have the crate list.
 assert-false: ".sidebar-elems .crate"
 assert-text: (".sidebar-elems > section ul > li:nth-child(1)", "Functions")