Allow links in doc blocks headings

Author: GuillaumeGomez

src/librustdoc/html/markdown.rs

@@ -539,7 +539,6 @@ impl<'a, 'b, 'ids, I: Iterator<Item = SpannedEvent<'a>>> Iterator
             for event in &mut self.inner {
                 match &event.0 {
                     Event::End(Tag::Heading(..)) => break,
-                    Event::Start(Tag::Link(_, _, _)) | Event::End(Tag::Link(..)) => {}
                     Event::Text(text) | Event::Code(text) => {
                         id.extend(text.chars().filter_map(slugify));
                         self.buf.push_back(event);

src/librustdoc/html/markdown/tests.rs

@@ -336,6 +336,13 @@ fn test_header() {
              <strong>Foo?</strong> &amp; *bar?!*  <em><code>baz</code></em> ❤ #qux\
          </h5>",
     );
+    t(
+        "# Foo [bar](https://hello.yo)",
+        "<h2 id=\"foo-bar\">\
+             <a class=\"doc-anchor\" href=\"#foo-bar\">§</a>\
+             Foo <a href=\"https://hello.yo\">bar</a>\
+         </h2>",
+    );
 }
 
 #[test]