Omit outer heading link if heading title contains a link

<a> tags can't be nested in HTML, so we omit the outer link on the
heading (that links to itself) if the title itself contains a link. This
avoids generating a nested <a> tag.

1 files changed, 18 insertions, 3 deletions

diff --git a/src/generate_html.rs b/src/generate_html.rs
index 6887f37..daa83d5 100644
--- a/src/generate_html.rs
+++ b/src/generate_html.rs
@@ -179,9 +179,24 @@ pub fn document_to_html(page: &Page, website: &Website) -> String {
                         Level::Heading2 => "h2",
                         Level::Heading3 => "h3",
                     };
-                    wrap!(heading_tag, format!("id='{url}'"), {
-                        tag!("a", line, format!("href='#{url}'"));
-                    });
+                    // Find out whether line contains a link.
+                    let mut contains_link = false;
+                    for token in &line.tokens {
+                        if let Token::InternalLink { .. } | Token::ExternalLink { .. } = token {
+                            contains_link = true;
+                            break;
+                        }
+                    }
+                    if !contains_link {
+                        wrap!(heading_tag, format!("id='{url}'"), {
+                            tag!("a", line, format!("href='#{url}'"));
+                        });
+                    } else {
+                        // Leave off the heading <a> tag if the heading already contains
+                        // a link (<a> tags cannot be nested).
+                        tag!(heading_tag, line, format!("id='{url}'"));
+                    }
+
                 }
                 Block::Paragraph(line) => tag!("p", line),
                 Block::Math(content) => html!("<div class='math'>{}</div>", sanitize_text(content, false)),