Rollup merge of rust-lang#104772 - GuillaumeGomez:small-accessibility-improvement, r=notriddle

Small accessibility improvements

From this [reddit post](https://www.reddit.com/r/rust/comments/z1gyz7/accessible_documentation/), I started to check a bit how to improve accessibility and how we could add test for it.

So these two fixes come from the use of the [pa11y tool](https://github.com/pa11y/pa11y). To make it work, I had to update its puppeteer version to the last one but otherwise it seems to be quite nice. I didn't fix all the errors it reported because they were about colors. To get the same result as mine, you can use this config:

```json
{
    "ignore": [
	"WCAG2AA.Principle1.Guideline1_4.1_4_3.G18.Fail",
	"WCAG2AA.Principle3.Guideline3_2.3_2_2.H32.2"
     ]
}
```

I think trying to improve accessibility is something we should definitely aim for. I'll try to integrate a tool to enforce this check (very likely `pa11y`) directly into the CI.

cc ``@jsha``
r? ``@notriddle``

Author: matthiaskrgr

src/librustdoc/html/render/mod.rs

@@ -1071,7 +1071,7 @@ fn write_impl_section_heading(w: &mut Buffer, title: &str, id: &str) {
         w,
         "<h2 id=\"{id}\" class=\"small-section-header\">\
             {title}\
-            <a href=\"#{id}\" class=\"anchor\"></a>\
+            <a href=\"#{id}\" class=\"anchor\">§</a>\
          </h2>"
     );
 }
@@ -1536,7 +1536,7 @@ fn render_impl(
                     render_rightside(w, cx, item, containing_item, render_mode);
                     if trait_.is_some() {
                         // Anchors are only used on trait impls.
-                        write!(w, "<a href=\"#{}\" class=\"anchor\"></a>", id);
+                        write!(w, "<a href=\"#{}\" class=\"anchor\">§</a>", id);
                     }
                     w.write_str("<h4 class=\"code-header\">");
                     render_assoc_item(
@@ -1562,7 +1562,7 @@ fn render_impl(
                 render_rightside(w, cx, item, containing_item, render_mode);
                 if trait_.is_some() {
                     // Anchors are only used on trait impls.
-                    write!(w, "<a href=\"#{}\" class=\"anchor\"></a>", id);
+                    write!(w, "<a href=\"#{}\" class=\"anchor\">§</a>", id);
                 }
                 w.write_str("<h4 class=\"code-header\">");
                 assoc_const(
@@ -1587,7 +1587,7 @@ fn render_impl(
                 write!(w, "<section id=\"{}\" class=\"{}{}\">", id, item_type, in_trait_class);
                 if trait_.is_some() {
                     // Anchors are only used on trait impls.
-                    write!(w, "<a href=\"#{}\" class=\"anchor\"></a>", id);
+                    write!(w, "<a href=\"#{}\" class=\"anchor\">§</a>", id);
                 }
                 w.write_str("<h4 class=\"code-header\">");
                 assoc_type(
@@ -1613,7 +1613,7 @@ fn render_impl(
                 );
                 if trait_.is_some() {
                     // Anchors are only used on trait impls.
-                    write!(w, "<a href=\"#{}\" class=\"anchor\"></a>", id);
+                    write!(w, "<a href=\"#{}\" class=\"anchor\">§</a>", id);
                 }
                 w.write_str("<h4 class=\"code-header\">");
                 assoc_type(
@@ -1846,7 +1846,7 @@ pub(crate) fn render_impl_summary(
     };
     write!(w, "<section id=\"{}\" class=\"impl has-srclink\"{}>", id, aliases);
     render_rightside(w, cx, &i.impl_item, containing_item, RenderMode::Normal);
-    write!(w, "<a href=\"#{}\" class=\"anchor\"></a>", id);
+    write!(w, "<a href=\"#{}\" class=\"anchor\">§</a>", id);
     write!(w, "<h3 class=\"code-header\">");
 
     if let Some(use_absolute) = use_absolute {

src/librustdoc/html/render/print_item.rs

@@ -717,7 +717,7 @@ fn item_trait(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, t: &clean:
         write!(
             w,
             "<h2 id=\"{0}\" class=\"small-section-header\">\
-                {1}<a href=\"#{0}\" class=\"anchor\"></a>\
+                {1}<a href=\"#{0}\" class=\"anchor\">§</a>\
              </h2>{2}",
             id, title, extra_content
         )
@@ -1147,7 +1147,7 @@ fn item_union(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, s: &clean:
         write!(
             w,
             "<h2 id=\"fields\" class=\"fields small-section-header\">\
-                Fields<a href=\"#fields\" class=\"anchor\"></a>\
+                Fields<a href=\"#fields\" class=\"anchor\">§</a>\
             </h2>"
         );
         for (field, ty) in fields {
@@ -1156,7 +1156,7 @@ fn item_union(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, s: &clean:
             write!(
                 w,
                 "<span id=\"{id}\" class=\"{shortty} small-section-header\">\
-                     <a href=\"#{id}\" class=\"anchor field\"></a>\
+                     <a href=\"#{id}\" class=\"anchor field\">§</a>\
                      <code>{name}: {ty}</code>\
                  </span>",
                 id = id,
@@ -1262,7 +1262,7 @@ fn item_enum(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, e: &clean::
         write!(
             w,
             "<h2 id=\"variants\" class=\"variants small-section-header\">\
-                Variants{}<a href=\"#variants\" class=\"anchor\"></a>\
+                Variants{}<a href=\"#variants\" class=\"anchor\">§</a>\
             </h2>",
             document_non_exhaustive_header(it)
         );
@@ -1273,7 +1273,7 @@ fn item_enum(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, e: &clean::
             write!(
                 w,
                 "<section id=\"{id}\" class=\"variant\">\
-                    <a href=\"#{id}\" class=\"anchor\"></a>",
+                    <a href=\"#{id}\" class=\"anchor\">§</a>",
                 id = id,
             );
             render_stability_since_raw_with_extra(
@@ -1325,7 +1325,7 @@ fn item_enum(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, e: &clean::
                                 w,
                                 "<div class=\"sub-variant-field\">\
                                  <span id=\"{id}\" class=\"small-section-header\">\
-                                     <a href=\"#{id}\" class=\"anchor field\"></a>\
+                                     <a href=\"#{id}\" class=\"anchor field\">§</a>\
                                      <code>{f}:&nbsp;{t}</code>\
                                  </span>",
                                 id = id,
@@ -1477,7 +1477,7 @@ fn item_struct(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, s: &clean
             write!(
                 w,
                 "<h2 id=\"fields\" class=\"fields small-section-header\">\
-                     {}{}<a href=\"#fields\" class=\"anchor\"></a>\
+                     {}{}<a href=\"#fields\" class=\"anchor\">§</a>\
                  </h2>",
                 if s.ctor_kind.is_none() { "Fields" } else { "Tuple Fields" },
                 document_non_exhaustive_header(it)
@@ -1490,7 +1490,7 @@ fn item_struct(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, s: &clean
                 write!(
                     w,
                     "<span id=\"{id}\" class=\"{item_type} small-section-header\">\
-                         <a href=\"#{id}\" class=\"anchor field\"></a>\
+                         <a href=\"#{id}\" class=\"anchor field\">§</a>\
                          <code>{name}: {ty}</code>\
                      </span>",
                     item_type = ItemType::StructField,
@@ -1908,7 +1908,7 @@ fn document_type_layout(w: &mut Buffer, cx: &Context<'_>, ty_def_id: DefId) {
     writeln!(
         w,
         "<h2 id=\"layout\" class=\"small-section-header\"> \
-        Layout<a href=\"#layout\" class=\"anchor\"></a></h2>"
+        Layout<a href=\"#layout\" class=\"anchor\">§</a></h2>"
     );
     writeln!(w, "<div class=\"docblock\">");
 

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

@@ -730,9 +730,6 @@ a {
 h2.small-section-header > .anchor {
 	padding-right: 6px;
 }
-.anchor::before {
-	content: '§';
-}
 
 .main-heading a:hover,
 .example-wrap > pre.rust a:hover,

src/librustdoc/html/templates/page.html

@@ -115,6 +115,7 @@ <h2></h2> {#- -#}
                     <input {# -#}
                         class="search-input" {# -#}
                         name="search" {# -#}
+                        aria-label="Run search in the documentation" {# -#}
                         autocomplete="off" {# -#}
                         spellcheck="false" {# -#}
                         placeholder="Click or press ‘S’ to search, ‘?’ for more options…" {# -#}