Add Markdown diagrams and render hooks for code blocks

You can now create custom hook templates for code blocks, either one for all (`render-codeblock.html`) or for a given code language (e.g. `render-codeblock-go.html`).

We also used this new hook to add support for diagrams in Hugo:

* Goat (Go ASCII Tool) is built-in and enabled by default; just create a fenced code block with the language `goat` and start draw your Ascii diagrams.
* Another popular alternative for diagrams in Markdown, Mermaid (supported by GitHub), can also be implemented with a simple template. See the Hugo documentation for more information.

Updates #7765
Closes #9538
Fixes #9553
Fixes #8520
Fixes #6702
Fixes #9558

16 files changed, 1130 insertions, 364 deletions

diff --git a/markup/converter/converter.go b/markup/converter/converter.go
index 180208a7b..30addfec6 100644
--- a/markup/converter/converter.go
+++ b/markup/converter/converter.go
@@ -21,6 +21,7 @@ import (
 	"github.com/gohugoio/hugo/config"
 	"github.com/gohugoio/hugo/identity"
 	"github.com/gohugoio/hugo/markup/converter/hooks"
+	"github.com/gohugoio/hugo/markup/highlight"
 	"github.com/gohugoio/hugo/markup/markup_config"
 	"github.com/gohugoio/hugo/markup/tableofcontents"
 	"github.com/spf13/afero"
@@ -34,7 +35,7 @@ type ProviderConfig struct {
 	ContentFs afero.Fs
 	Logger    loggers.Logger
 	Exec      *hexec.Exec
-	Highlight func(code, lang, optsStr string) (string, error)
+	highlight.Highlighter
 }
 
 // ProviderProvider creates converter providers.
@@ -127,9 +128,10 @@ type DocumentContext struct {
 
 // RenderContext holds contextual information about the content to render.
 type RenderContext struct {
-	Src         []byte
-	RenderTOC   bool
-	RenderHooks hooks.Renderers
+	Src       []byte
+	RenderTOC bool
+
+	GetRenderer hooks.GetRendererFunc
 }
 
 var FeatureRenderHooks = identity.NewPathIdentity("markup", "renderingHooks")
diff --git a/markup/converter/hooks/hooks.go b/markup/converter/hooks/hooks.go
index d36dad288..987cb1dc3 100644
--- a/markup/converter/hooks/hooks.go
+++ b/markup/converter/hooks/hooks.go
@@ -14,15 +14,17 @@
 package hooks
 
 import (
-	"fmt"
 	"io"
-	"strings"
 
+	"github.com/gohugoio/hugo/common/hugio"
 	"github.com/gohugoio/hugo/identity"
+	"github.com/gohugoio/hugo/markup/internal/attributes"
 )
 
+var _ AttributesOptionsSliceProvider = (*attributes.AttributesHolder)(nil)
+
 type AttributesProvider interface {
-	Attributes() map[string]string
+	Attributes() map[string]interface{}
 }
 
 type LinkContext interface {
@@ -33,11 +35,30 @@ type LinkContext interface {
 	PlainText() string
 }
 
+type CodeblockContext interface {
+	AttributesProvider
+	Options() map[string]interface{}
+	Lang() string
+	Code() string
+	Ordinal() int
+	Page() interface{}
+}
+
+type AttributesOptionsSliceProvider interface {
+	AttributesSlice() []attributes.Attribute
+	OptionsSlice() []attributes.Attribute
+}
+
 type LinkRenderer interface {
 	RenderLink(w io.Writer, ctx LinkContext) error
 	identity.Provider
 }
 
+type CodeBlockRenderer interface {
+	RenderCodeblock(w hugio.FlexiWriter, ctx CodeblockContext) error
+	identity.Provider
+}
+
 // HeadingContext contains accessors to all attributes that a HeadingRenderer
 // can use to render a heading.
 type HeadingContext interface {
@@ -63,70 +84,13 @@ type HeadingRenderer interface {
 	identity.Provider
 }
 
-type Renderers struct {
-	LinkRenderer    LinkRenderer
-	ImageRenderer   LinkRenderer
-	HeadingRenderer HeadingRenderer
-}
-
-func (r Renderers) Eq(other interface{}) bool {
-	ro, ok := other.(Renderers)
-	if !ok {
-		return false
-	}
-
-	if r.IsZero() || ro.IsZero() {
-		return r.IsZero() && ro.IsZero()
-	}
-
-	var b1, b2 bool
-	b1, b2 = r.ImageRenderer == nil, ro.ImageRenderer == nil
-	if (b1 || b2) && (b1 != b2) {
-		return false
-	}
-	if !b1 && r.ImageRenderer.GetIdentity() != ro.ImageRenderer.GetIdentity() {
-		return false
-	}
-
-	b1, b2 = r.LinkRenderer == nil, ro.LinkRenderer == nil
-	if (b1 || b2) && (b1 != b2) {
-		return false
-	}
-	if !b1 && r.LinkRenderer.GetIdentity() != ro.LinkRenderer.GetIdentity() {
-		return false
-	}
-
-	b1, b2 = r.HeadingRenderer == nil, ro.HeadingRenderer == nil
-	if (b1 || b2) && (b1 != b2) {
-		return false
-	}
-	if !b1 && r.HeadingRenderer.GetIdentity() != ro.HeadingRenderer.GetIdentity() {
-		return false
-	}
-
-	return true
-}
-
-func (r Renderers) IsZero() bool {
-	return r.HeadingRenderer == nil && r.LinkRenderer == nil && r.ImageRenderer == nil
-}
+type RendererType int
 
-func (r Renderers) String() string {
-	if r.IsZero() {
-		return "<zero>"
-	}
-
-	var sb strings.Builder
-
-	if r.LinkRenderer != nil {
-		sb.WriteString(fmt.Sprintf("LinkRenderer<%s>|", r.LinkRenderer.GetIdentity()))
-	}
-	if r.HeadingRenderer != nil {
-		sb.WriteString(fmt.Sprintf("HeadingRenderer<%s>|", r.HeadingRenderer.GetIdentity()))
-	}
-	if r.ImageRenderer != nil {
-		sb.WriteString(fmt.Sprintf("ImageRenderer<%s>|", r.ImageRenderer.GetIdentity()))
-	}
+const (
+	LinkRendererType RendererType = iota + 1
+	ImageRendererType
+	HeadingRendererType
+	CodeBlockRendererType
+)
 
-	return sb.String()
-}
+type GetRendererFunc func(t RendererType, id interface{}) interface{}
diff --git a/markup/goldmark/codeblocks/integration_test.go b/markup/goldmark/codeblocks/integration_test.go
new file mode 100644
index 000000000..d662b3911
--- /dev/null
+++ b/markup/goldmark/codeblocks/integration_test.go
@@ -0,0 +1,115 @@
+// Copyright 2022 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package codeblocks_test
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/gohugoio/hugo/hugolib"
+)
+
+func TestCodeblocks(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- config.toml --
+[markup]
+  [markup.highlight]
+    anchorLineNos = false
+    codeFences = true
+    guessSyntax = false
+    hl_Lines = ''
+    lineAnchors = ''
+    lineNoStart = 1
+    lineNos = false
+    lineNumbersInTable = true
+    noClasses = false
+    style = 'monokai'
+    tabWidth = 4
+-- layouts/_default/_markup/render-codeblock-goat.html --
+{{ $diagram := diagrams.Goat .Code }}
+Goat SVG:{{ substr $diagram.SVG 0 100 | safeHTML }}  }}|
+Goat Attribute: {{ .Attributes.width}}|
+-- layouts/_default/_markup/render-codeblock-go.html --
+Go Code: {{ .Code | safeHTML }}|
+Go Language: {{ .Lang }}|
+-- layouts/_default/single.html --
+{{ .Content }}
+-- content/p1.md --
+---
+title: "p1"
+---
+
+## Ascii Diagram
+
+CODE_FENCEgoat { width="600" }
+--->
+CODE_FENCE
+
+## Go Code
+
+CODE_FENCEgo
+fmt.Println("Hello, World!");
+CODE_FENCE
+
+## Golang Code
+
+CODE_FENCEgolang
+fmt.Println("Hello, Golang!");
+CODE_FENCE
+
+## Bash Code
+
+CODE_FENCEbash { linenos=inline,hl_lines=[2,"5-6"],linenostart=32 class=blue }
+echo "l1";
+echo "l2";
+echo "l3";
+echo "l4";
+echo "l5";
+echo "l6";
+echo "l7";
+echo "l8";
+CODE_FENCE
+`
+
+	files = strings.ReplaceAll(files, "CODE_FENCE", "```")
+
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+			NeedsOsFS:   false,
+		},
+	).Build()
+
+	b.AssertFileContent("public/p1/index.html", `
+Goat SVG:<svg class='diagram'
+Goat Attribute: 600|
+
+Go Language: go|
+Go Code: fmt.Println("Hello, World!");
+
+Go Code: fmt.Println("Hello, Golang!");
+Go Language: golang|
+
+
+	`,
+		"Goat SVG:<svg class='diagram' xmlns='http://www.w3.org/2000/svg' version='1.1' height='25' width='40'",
+		"Goat Attribute: 600|",
+		"<h2 id=\"go-code\">Go Code</h2>\nGo Code: fmt.Println(\"Hello, World!\");\n|\nGo Language: go|",
+		"<h2 id=\"golang-code\">Golang Code</h2>\nGo Code: fmt.Println(\"Hello, Golang!\");\n|\nGo Language: golang|",
+		"<h2 id=\"bash-code\">Bash Code</h2>\n<div class=\"highlight blue\"><pre tabindex=\"0\" class=\"chroma\"><code class=\"language-bash\" data-lang=\"bash\"><span class=\"line\"><span class=\"ln\">32</span><span class=\"cl\"><span class=\"nb\">echo</span> <span class=\"s2\">&#34;l1&#34;</span><span class=\"p\">;</span>\n</span></span><span class=\"line hl\"><span class=\"ln\">33</span>",
+	)
+}
diff --git a/markup/goldmark/codeblocks/render.go b/markup/goldmark/codeblocks/render.go
new file mode 100644
index 000000000..59d142e23
--- /dev/null
+++ b/markup/goldmark/codeblocks/render.go
@@ -0,0 +1,159 @@
+// Copyright 2022 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package codeblocks
+
+import (
+	"bytes"
+	"fmt"
+
+	"github.com/gohugoio/hugo/markup/converter/hooks"
+	"github.com/gohugoio/hugo/markup/goldmark/internal/render"
+	"github.com/gohugoio/hugo/markup/internal/attributes"
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type (
+	diagrams     struct{}
+	htmlRenderer struct{}
+)
+
+func New() goldmark.Extender {
+	return &diagrams{}
+}
+
+func (e *diagrams) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(
+		parser.WithASTTransformers(
+			util.Prioritized(&Transformer{}, 100),
+		),
+	)
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(
+		util.Prioritized(newHTMLRenderer(), 100),
+	))
+}
+
+func newHTMLRenderer() renderer.NodeRenderer {
+	r := &htmlRenderer{}
+	return r
+}
+
+func (r *htmlRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(KindCodeBlock, r.renderCodeBlock)
+}
+
+func (r *htmlRenderer) renderCodeBlock(w util.BufWriter, src []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	ctx := w.(*render.Context)
+
+	if entering {
+		return ast.WalkContinue, nil
+	}
+
+	n := node.(*codeBlock)
+	lang := string(n.b.Language(src))
+	ordinal := n.ordinal
+
+	var buff bytes.Buffer
+
+	l := n.b.Lines().Len()
+	for i := 0; i < l; i++ {
+		line := n.b.Lines().At(i)
+		buff.Write(line.Value(src))
+	}
+	text := buff.String()
+
+	var info []byte
+	if n.b.Info != nil {
+		info = n.b.Info.Segment.Value(src)
+	}
+	attrs := getAttributes(n.b, info)
+
+	v := ctx.RenderContext().GetRenderer(hooks.CodeBlockRendererType, lang)
+	if v == nil {
+		return ast.WalkStop, fmt.Errorf("no code renderer found for %q", lang)
+	}
+
+	cr := v.(hooks.CodeBlockRenderer)
+
+	err := cr.RenderCodeblock(
+		w,
+		codeBlockContext{
+			page:             ctx.DocumentContext().Document,
+			lang:             lang,
+			code:             text,
+			ordinal:          ordinal,
+			AttributesHolder: attributes.New(attrs, attributes.AttributesOwnerCodeBlock),
+		},
+	)
+
+	ctx.AddIdentity(cr)
+
+	return ast.WalkContinue, err
+}
+
+type codeBlockContext struct {
+	page    interface{}
+	lang    string
+	code    string
+	ordinal int
+	*attributes.AttributesHolder
+}
+
+func (c codeBlockContext) Page() interface{} {
+	return c.page
+}
+
+func (c codeBlockContext) Lang() string {
+	return c.lang
+}
+
+func (c codeBlockContext) Code() string {
+	return c.code
+}
+
+func (c codeBlockContext) Ordinal() int {
+	return c.ordinal
+}
+
+func getAttributes(node *ast.FencedCodeBlock, infostr []byte) []ast.Attribute {
+	if node.Attributes() != nil {
+		return node.Attributes()
+	}
+	if infostr != nil {
+		attrStartIdx := -1
+
+		for idx, char := range infostr {
+			if char == '{' {
+				attrStartIdx = idx
+				break
+			}
+		}
+
+		if attrStartIdx > 0 {
+			n := ast.NewTextBlock() // dummy node for storing attributes
+			attrStr := infostr[attrStartIdx:]
+			if attrs, hasAttr := parser.ParseAttributes(text.NewReader(attrStr)); hasAttr {
+				for _, attr := range attrs {
+					n.SetAttribute(attr.Name, attr.Value)
+				}
+				return n.Attributes()
+			}
+		}
+	}
+	return nil
+}
diff --git a/markup/goldmark/codeblocks/transform.go b/markup/goldmark/codeblocks/transform.go
new file mode 100644
index 000000000..791e99a5c
--- /dev/null
+++ b/markup/goldmark/codeblocks/transform.go
@@ -0,0 +1,53 @@
+package codeblocks
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/text"
+)
+
+// Kind is the kind of an Hugo code block.
+var KindCodeBlock = ast.NewNodeKind("HugoCodeBlock")
+
+// Its raw contents are the plain text of the code block.
+type codeBlock struct {
+	ast.BaseBlock
+	ordinal int
+	b       *ast.FencedCodeBlock
+}
+
+func (*codeBlock) Kind() ast.NodeKind { return KindCodeBlock }
+
+func (*codeBlock) IsRaw() bool { return true }
+
+func (b *codeBlock) Dump(src []byte, level int) {
+}
+
+type Transformer struct{}
+
+// Transform transforms the provided Markdown AST.
+func (*Transformer) Transform(doc *ast.Document, reader text.Reader, pctx parser.Context) {
+	var codeBlocks []*ast.FencedCodeBlock
+
+	ast.Walk(doc, func(node ast.Node, enter bool) (ast.WalkStatus, error) {
+		if !enter {
+			return ast.WalkContinue, nil
+		}
+
+		cb, ok := node.(*ast.FencedCodeBlock)
+		if !ok {
+			return ast.WalkContinue, nil
+		}
+
+		codeBlocks = append(codeBlocks, cb)
+		return ast.WalkContinue, nil
+	})
+
+	for i, cb := range codeBlocks {
+		b := &codeBlock{b: cb, ordinal: i}
+		parent := cb.Parent()
+		if parent != nil {
+			parent.ReplaceChild(parent, cb, b)
+		}
+	}
+}
diff --git a/markup/goldmark/convert.go b/markup/goldmark/convert.go
index c547fe1e0..4c1641a0b 100644
--- a/markup/goldmark/convert.go
+++ b/markup/goldmark/convert.go
@@ -17,12 +17,12 @@ package goldmark
 import (
 	"bytes"
 	"fmt"
-	"math/bits"
 	"path/filepath"
 	"runtime/debug"
 
+	"github.com/gohugoio/hugo/markup/goldmark/codeblocks"
 	"github.com/gohugoio/hugo/markup/goldmark/internal/extensions/attributes"
-	"github.com/yuin/goldmark/ast"
+	"github.com/gohugoio/hugo/markup/goldmark/internal/render"
 
 	"github.com/gohugoio/hugo/identity"
 
@@ -32,16 +32,13 @@ import (
 
 	"github.com/gohugoio/hugo/hugofs"
 	"github.com/gohugoio/hugo/markup/converter"
-	"github.com/gohugoio/hugo/markup/highlight"
 	"github.com/gohugoio/hugo/markup/tableofcontents"
 	"github.com/yuin/goldmark"
-	hl "github.com/yuin/goldmark-highlighting"
 	"github.com/yuin/goldmark/extension"
 	"github.com/yuin/goldmark/parser"
 	"github.com/yuin/goldmark/renderer"
 	"github.com/yuin/goldmark/renderer/html"
 	"github.com/yuin/goldmark/text"
-	"github.com/yuin/goldmark/util"
 )
 
 // Provider is the package entry point.
@@ -104,7 +101,7 @@ func newMarkdown(pcfg converter.ProviderConfig) goldmark.Markdown {
 	)
 
 	if mcfg.Highlight.CodeFences {
-		extensions = append(extensions, newHighlighting(mcfg.Highlight))
+		extensions = append(extensions, codeblocks.New())
 	}
 
 	if cfg.Extensions.Table {
@@ -178,65 +175,6 @@ func (c converterResult) GetIdentities() identity.Identities {
 	return c.ids
 }
 
-type bufWriter struct {
-	*bytes.Buffer
-}
-
-const maxInt = 1<<(bits.UintSize-1) - 1
-
-func (b *bufWriter) Available() int {
-	return maxInt
-}
-
-func (b *bufWriter) Buffered() int {
-	return b.Len()
-}
-
-func (b *bufWriter) Flush() error {
-	return nil
-}
-
-type renderContext struct {
-	*bufWriter
-	positions []int
-	renderContextData
-}
-
-func (ctx *renderContext) pushPos(n int) {
-	ctx.positions = append(ctx.positions, n)
-}
-
-func (ctx *renderContext) popPos() int {
-	i := len(ctx.positions) - 1
-	p := ctx.positions[i]
-	ctx.positions = ctx.positions[:i]
-	return p
-}
-
-type renderContextData interface {
-	RenderContext() converter.RenderContext
-	DocumentContext() converter.DocumentContext
-	AddIdentity(id identity.Provider)
-}
-
-type renderContextDataHolder struct {
-	rctx converter.RenderContext
-	dctx converter.DocumentContext
-	ids  identity.Manager
-}
-
-func (ctx *renderContextDataHolder) RenderContext() converter.RenderContext {
-	return ctx.rctx
-}
-
-func (ctx *renderContextDataHolder) DocumentContext() converter.DocumentContext {
-	return ctx.dctx
-}
-
-func (ctx *renderContextDataHolder) AddIdentity(id identity.Provider) {
-	ctx.ids.Add(id)
-}
-
 var converterIdentity = identity.KeyValueIdentity{Key: "goldmark", Value: "converter"}
 
 func (c *goldmarkConverter) Convert(ctx converter.RenderContext) (result converter.Result, err error) {
@@ -251,7 +189,7 @@ func (c *goldmarkConverter) Convert(ctx converter.RenderContext) (result convert
 		}
 	}()
 
-	buf := &bufWriter{Buffer: &bytes.Buffer{}}
+	buf := &render.BufWriter{Buffer: &bytes.Buffer{}}
 	result = buf
 	pctx := c.newParserContext(ctx)
 	reader := text.NewReader(ctx.Src)
@@ -261,15 +199,15 @@ func (c *goldmarkConverter) Convert(ctx converter.RenderContext) (result convert
 		parser.WithContext(pctx),
 	)
 
-	rcx := &renderContextDataHolder{
-		rctx: ctx,
-		dctx: c.ctx,
-		ids:  identity.NewManager(converterIdentity),
+	rcx := &render.RenderContextDataHolder{
+		Rctx: ctx,
+		Dctx: c.ctx,
+		IDs:  identity.NewManager(converterIdentity),
 	}
 
-	w := &renderContext{
-		bufWriter:         buf,
-		renderContextData: rcx,
+	w := &render.Context{
+		BufWriter:   buf,
+		ContextData: rcx,
 	}
 
 	if err := c.md.Renderer().Render(w, ctx.Src, doc); err != nil {
@@ -278,7 +216,7 @@ func (c *goldmarkConverter) Convert(ctx converter.RenderContext) (result convert
 
 	return converterResult{
 		Result: buf,
-		ids:    rcx.ids.GetIdentities(),
+		ids:    rcx.IDs.GetIdentities(),
 		toc:    pctx.TableOfContents(),
 	}, nil
 }
@@ -309,63 +247,3 @@ func (p *parserContext) TableOfContents() tableofcontents.Root {
 	}
 	return tableofcontents.Root{}
 }
-
-func newHighlighting(cfg highlight.Config) goldmark.Extender {
-	return hl.NewHighlighting(
-		hl.WithStyle(cfg.Style),
-		hl.WithGuessLanguage(cfg.GuessSyntax),
-		hl.WithCodeBlockOptions(highlight.GetCodeBlockOptions()),
-		hl.WithFormatOptions(
-			cfg.ToHTMLOptions()...,
-		),
-
-		hl.WithWrapperRenderer(func(w util.BufWriter, ctx hl.CodeBlockContext, entering bool) {
-			var language string
-			if l, hasLang := ctx.Language(); hasLang {
-				language = string(l)
-			}
-
-			if ctx.Highlighted() {
-				if entering {
-					writeDivStart(w, ctx)
-				} else {
-					writeDivEnd(w)
-				}
-			} else {
-				if entering {
-					highlight.WritePreStart(w, language, "")
-				} else {
-					highlight.WritePreEnd(w)
-				}
-			}
-		}),
-	)
-}
-
-func writeDivStart(w util.BufWriter, ctx hl.CodeBlockContext) {
-	w.WriteString(`<div class="highlight`)
-
-	var attributes []ast.Attribute
-	if ctx.Attributes() != nil {
-		attributes = ctx.Attributes().All()
-	}
-
-	if attributes != nil {
-		class, found := ctx.Attributes().GetString("class")
-		if found {
-			w.WriteString(" ")
-			w.Write(util.EscapeHTML(class.([]byte)))
-
-		}
-		_, _ = w.WriteString("\"")
-		renderAttributes(w, true, attributes...)
-	} else {
-		_, _ = w.WriteString("\"")
-	}
-
-	w.WriteString(">")
-}
-
-func writeDivEnd(w util.BufWriter) {
-	w.WriteString("</div>")
-}
diff --git a/markup/goldmark/convert_test.go b/markup/goldmark/convert_test.go
index 684f22c54..ecb308eba 100644
--- a/markup/goldmark/convert_test.go
+++ b/markup/goldmark/convert_test.go
@@ -20,6 +20,7 @@ import (
 
 	"github.com/spf13/cast"
 
+	"github.com/gohugoio/hugo/markup/converter/hooks"
 	"github.com/gohugoio/hugo/markup/goldmark/goldmark_config"
 
 	"github.com/gohugoio/hugo/markup/highlight"
@@ -41,9 +42,18 @@ func convert(c *qt.C, mconf markup_config.Config, content string) converter.Resu
 		},
 	)
 	c.Assert(err, qt.IsNil)
+	h := highlight.New(mconf.Highlight)
+
+	getRenderer := func(t hooks.RendererType, id interface{}) interface{} {
+		if t == hooks.CodeBlockRendererType {
+			return h
+		}
+		return nil
+	}
+
 	conv, err := p.New(converter.DocumentContext{DocumentID: "thedoc"})
 	c.Assert(err, qt.IsNil)
-	b, err := conv.Convert(converter.RenderContext{RenderTOC: true, Src: []byte(content)})
+	b, err := conv.Convert(converter.RenderContext{RenderTOC: true, Src: []byte(content), GetRenderer: getRenderer})
 	c.Assert(err, qt.IsNil)
 
 	return b
@@ -372,12 +382,21 @@ LINE5
 			},
 		)
 
+		h := highlight.New(conf)
+
+		getRenderer := func(t hooks.RendererType, id interface{}) interface{} {
+			if t == hooks.CodeBlockRendererType {
+				return h
+			}
+			return nil
+		}
+
 		content := "```" + language + "\n" + code + "\n```"
 
 		c.Assert(err, qt.IsNil)
 		conv, err := p.New(converter.DocumentContext{})
 		c.Assert(err, qt.IsNil)
-		b, err := conv.Convert(converter.RenderContext{Src: []byte(content)})
+		b, err := conv.Convert(converter.RenderContext{Src: []byte(content), GetRenderer: getRenderer})
 		c.Assert(err, qt.IsNil)
 
 		return string(b.Bytes())
@@ -391,7 +410,7 @@ LINE5
 		// TODO(bep) there is a whitespace mismatch (\n) between this and the highlight template func.
 		c.Assert(result, qt.Equals, "<div class=\"highlight\"><pre tabindex=\"0\" class=\"chroma\"><code class=\"language-bash\" data-lang=\"bash\"><span class=\"line\"><span class=\"cl\"><span class=\"nb\">echo</span> <span class=\"s2\">&#34;Hugo Rocks!&#34;</span>\n</span></span></code></pre></div>")
 		result = convertForConfig(c, cfg, `echo "Hugo Rocks!"`, "unknown")
-		c.Assert(result, qt.Equals, "<pre tabindex=\"0\"><code class=\"language-unknown\" data-lang=\"unknown\">echo &quot;Hugo Rocks!&quot;\n</code></pre>")
+		c.Assert(result, qt.Equals, "<pre tabindex=\"0\"><code class=\"language-unknown\" data-lang=\"unknown\">echo &#34;Hugo Rocks!&#34;\n</code></pre>")
 	})
 
 	c.Run("Highlight lines, default config", func(c *qt.C) {
diff --git a/markup/goldmark/integration_test.go b/markup/goldmark/integration_test.go
index 4ace04f75..f1fa745c5 100644
--- a/markup/goldmark/integration_test.go
+++ b/markup/goldmark/integration_test.go
@@ -36,12 +36,12 @@ func TestAttributeExclusion(t *testing.T) {
 ---
 title: "p1"
 ---
-## Heading {class="a" onclick="alert('heading')" linenos="inline"}
+## Heading {class="a" onclick="alert('heading')"}
 
 > Blockquote
-{class="b" ondblclick="alert('blockquote')" LINENOS="inline"}
+{class="b" ondblclick="alert('blockquote')"}
 
-~~~bash {id="c" onmouseover="alert('code fence')"}
+~~~bash {id="c" onmouseover="alert('code fence')" LINENOS=true}
 foo
 ~~~
 -- layouts/_default/single.html --
@@ -96,6 +96,63 @@ title: "p1"
 	`)
 }
 
+func TestAttributesDefaultRenderer(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- content/p1.md --
+---
+title: "p1"
+---
+## Heading Attribute Which Needs Escaping { class="a < b" }
+-- layouts/_default/single.html --
+{{ .Content }}
+`
+
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+			NeedsOsFS:   false,
+		},
+	).Build()
+
+	b.AssertFileContent("public/p1/index.html", `
+class="a &lt; b"
+	`)
+}
+
+// Issue 9558.
+func TestAttributesHookNoEscape(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- content/p1.md --
+---
+title: "p1"
+---
+## Heading Attribute Which Needs Escaping { class="Smith & Wesson" }
+-- layouts/_default/_markup/render-heading.html --
+plain: |{{- range $k, $v := .Attributes -}}{{ $k }}: {{ $v }}|{{ end }}|
+safeHTML: |{{- range $k, $v := .Attributes -}}{{ $k }}: {{ $v | safeHT