markup/goldmark: Add strikethrough extension to toc renderer

Configure the TOC (TableOfContents, toc.go) goldmark renderer to always
enable the Strikethrough extension. This allows handling ast.KindStrikethrough
within an AST node.

The last test in TestEscapeToc() is corrected to not expect <div>
elements to be included in the TOC renderer output.

Fixes #7169
Fixes #8087
Fixes #11783

markup/goldmark/convert.go

@@ -17,6 +17,8 @@ package goldmark
 import (
 	"bytes"
 
+	"github.com/yuin/goldmark/util"
+
 	"github.com/gohugoio/hugo/identity"
 
 	"github.com/gohugoio/hugo/markup/goldmark/codeblocks"
@@ -25,8 +27,6 @@ import (
 	"github.com/gohugoio/hugo/markup/goldmark/internal/extensions/attributes"
 	"github.com/gohugoio/hugo/markup/goldmark/internal/render"
 
-	"github.com/gohugoio/hugo/markup/converter"
-	"github.com/gohugoio/hugo/markup/tableofcontents"
 	"github.com/yuin/goldmark"
 	emoji "github.com/yuin/goldmark-emoji"
 	"github.com/yuin/goldmark/ast"
@@ -35,6 +35,9 @@ import (
 	"github.com/yuin/goldmark/renderer"
 	"github.com/yuin/goldmark/renderer/html"
 	"github.com/yuin/goldmark/text"
+
+	"github.com/gohugoio/hugo/markup/converter"
+	"github.com/gohugoio/hugo/markup/tableofcontents"
 )
 
 const (
@@ -79,23 +82,32 @@ func newMarkdown(pcfg converter.ProviderConfig) goldmark.Markdown {
 	mcfg := pcfg.MarkupConfig()
 	cfg := mcfg.Goldmark
 	var rendererOptions []renderer.Option
+	var htmlOptions []html.Option
 
 	if cfg.Renderer.HardWraps {
 		rendererOptions = append(rendererOptions, html.WithHardWraps())
+		htmlOptions = append(htmlOptions, html.WithHardWraps())
 	}
 
 	if cfg.Renderer.XHTML {
 		rendererOptions = append(rendererOptions, html.WithXHTML())
+		htmlOptions = append(htmlOptions, html.WithXHTML())
 	}
 
 	if cfg.Renderer.Unsafe {
 		rendererOptions = append(rendererOptions, html.WithUnsafe())
+		htmlOptions = append(htmlOptions, html.WithUnsafe())
 	}
 
+	tocRendererOptions := make([]renderer.Option, 0)
+	if rendererOptions != nil {
+		copy(tocRendererOptions, rendererOptions)
+	}
+	tocRendererOptions = append(tocRendererOptions, renderer.WithNodeRenderers(util.Prioritized(extension.NewStrikethroughHTMLRenderer(htmlOptions...), 100)))
 	var (
 		extensions = []goldmark.Extender{
 			newLinks(cfg),
-			newTocExtension(rendererOptions),
+			newTocExtension(tocRendererOptions),
 		}
 		parserOptions []parser.Option
 	)

markup/goldmark/toc_test.go

@@ -123,7 +123,7 @@ func TestEscapeToc(t *testing.T) {
 	c.Assert(got, qt.Equals, `<nav id="TableOfContents">
   <ul>
     <li><a href="#a--b--c--d">A &lt; B &amp; C &gt; D</a></li>
-    <li><a href="#a--b--c--d-divfoodiv">A &lt; B &amp; C &gt; D <div>foo</div></a></li>
+    <li><a href="#a--b--c--d-divfoodiv">A &lt; B &amp; C &gt; D <!-- raw HTML omitted -->foo<!-- raw HTML omitted --></a></li>
     <li><a href="#emphasis"><em>EMPHASIS</em></a></li>
     <li><a href="#echo-codeblock"><code>echo codeblock</code></a></li>
   </ul>