rustdoc: change `.src-line-numbers > span` to `.src-line-numbers > a`

This allows people to treat them like real links, such as right-click to
copy URL, and makes the line numbers in a scraped example work at all,
when before this commit was added, they had the clickable pointer cursor
but did not actually do anything when clicked.

4 files changed, 27 insertions, 21 deletions

diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index 27dea8ec0b3..e09106077f7 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -2888,9 +2888,6 @@ fn render_call_locations(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Ite
         })()
         .unwrap_or(rustc_span::DUMMY_SP);
 
-        // The root path is the inverse of Context::current
-        let root_path = vec!["../"; cx.current.len() - 1].join("");
-
         let mut decoration_info = FxHashMap::default();
         decoration_info.insert("highlight focus", vec![byte_ranges.remove(0)]);
         decoration_info.insert("highlight", byte_ranges);
@@ -2900,9 +2897,13 @@ fn render_call_locations(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Ite
             contents_subset,
             file_span,
             cx,
-            &root_path,
+            &cx.root_path(),
             highlight::DecorationInfo(decoration_info),
-            sources::SourceContext::Embedded { offset: line_min, needs_expansion },
+            sources::SourceContext::Embedded {
+                url: &call_data.url,
+                offset: line_min,
+                needs_expansion,
+            },
         );
         write!(w, "</div></div>");
 
diff --git a/src/librustdoc/html/sources.rs b/src/librustdoc/html/sources.rs
index 8a01c01049d..99b4678c457 100644
--- a/src/librustdoc/html/sources.rs
+++ b/src/librustdoc/html/sources.rs
@@ -256,9 +256,9 @@ where
     }
 }
 
-pub(crate) enum SourceContext {
+pub(crate) enum SourceContext<'a> {
     Standalone,
-    Embedded { offset: usize, needs_expansion: bool },
+    Embedded { url: &'a str, offset: usize, needs_expansion: bool },
 }
 
 /// Wrapper struct to render the source code of a file. This will do things like
@@ -270,31 +270,32 @@ pub(crate) fn print_src(
     context: &Context<'_>,
     root_path: &str,
     decoration_info: highlight::DecorationInfo,
-    source_context: SourceContext,
+    source_context: SourceContext<'_>,
 ) {
     let lines = s.lines().count();
     let mut line_numbers = Buffer::empty_from(buf);
     let extra;
     line_numbers.write_str("<pre class=\"src-line-numbers\">");
+    let current_href = &context
+        .href_from_span(clean::Span::new(file_span), false)
+        .expect("only local crates should have sources emitted");
     match source_context {
         SourceContext::Standalone => {
             extra = None;
             for line in 1..=lines {
-                writeln!(line_numbers, "<span id=\"{0}\">{0}</span>", line)
+                writeln!(line_numbers, "<a href=\"#{line}\" id=\"{line}\">{line}</a>")
             }
         }
-        SourceContext::Embedded { offset, needs_expansion } => {
+        SourceContext::Embedded { url, offset, needs_expansion } => {
             extra =
                 if needs_expansion { Some(r#"<span class="expand">&varr;</span>"#) } else { None };
-            for line in 1..=lines {
-                writeln!(line_numbers, "<span>{0}</span>", line + offset)
+            for line_number in 1..=lines {
+                let line = line_number + offset;
+                writeln!(line_numbers, "<a href=\"{root_path}{url}#{line}\">{line}</a>")
             }
         }
     }
     line_numbers.write_str("</pre>");
-    let current_href = &context
-        .href_from_span(clean::Span::new(file_span), false)
-        .expect("only local crates should have sources emitted");
     highlight::render_source_with_highlighting(
         s,
         buf,
diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index 894499e5c4f..df7b6e9b99a 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -575,8 +575,7 @@ ul.block, .block li {
 	border-color: var(--example-line-numbers-border-color);
 }
 
-.src-line-numbers span {
-	cursor: pointer;
+.src-line-numbers a {
 	color: var(--src-line-numbers-span-color);
 }
 .src-line-numbers .line-highlighted {
@@ -2060,7 +2059,7 @@ in storage.js
 	padding: 14px 0;
 }
 
-.scraped-example .code-wrapper .src-line-numbers span {
+.scraped-example .code-wrapper .src-line-numbers a {
 	padding: 0 14px;
 }
 
diff --git a/src/librustdoc/html/static/js/source-script.js b/src/librustdoc/html/static/js/source-script.js
index 0b9368dd899..5db768c1c57 100644
--- a/src/librustdoc/html/static/js/source-script.js
+++ b/src/librustdoc/html/static/js/source-script.js
@@ -157,7 +157,7 @@ function highlightSourceLines(match) {
         x.scrollIntoView();
     }
     onEachLazy(document.getElementsByClassName("src-line-numbers"), e => {
-        onEachLazy(e.getElementsByTagName("span"), i_e => {
+        onEachLazy(e.getElementsByTagName("a"), i_e => {
             removeClass(i_e, "line-highlighted");
         });
     });
@@ -188,8 +188,13 @@ const handleSourceHighlight = (function() {
 
     return ev => {
         let cur_line_id = parseInt(ev.target.id, 10);
-        // It can happen when clicking not on a line number span.
-        if (isNaN(cur_line_id)) {
+        // This event handler is attached to the entire line number column, but it should only
+        // be run if one of the anchors is clicked. It also shouldn't do anything if the anchor
+        // is clicked with a modifier key (to open a new browser tab).
+        if (isNaN(cur_line_id) ||
+            ev.ctrlKey ||
+            ev.altKey ||
+            ev.metaKey) {
             return;
         }
         ev.preventDefault();