Fix indentation in highlight shortcode

Fixes gohugoio#4717

hugolib/shortcode.go

@@ -62,6 +62,9 @@ type ShortcodeWithPage struct {
 	// this ordinal will represent the position of this shortcode in the page content.
 	Ordinal int
 
+	// Indentation before the opening shortcode.
+	indentation string
+
 	// pos is the position in bytes in the source file. Used for error logging.
 	posInit   sync.Once
 	posOffset int
@@ -70,6 +73,24 @@ type ShortcodeWithPage struct {
 	scratch *maps.Scratch
 }
 
+// InnerDeindented returns the (potentially de-indented) inner content of the shortcode.
+func (scp *ShortcodeWithPage) InnerDeindented() template.HTML {
+	if scp.indentation == "" {
+		return scp.Inner
+	}
+	var sb strings.Builder
+	text.VisitLinesAfter(string(scp.Inner), func(s string) {
+		//fmt.Printf("%s=>%s", util.VisualizeSpaces([]byte(scp.indentation)), util.VisualizeSpaces([]byte(s)))
+		if strings.HasPrefix(s, scp.indentation) {
+			sb.WriteString(strings.TrimPrefix(s, scp.indentation))
+		} else {
+			sb.WriteString(s)
+		}
+	})
+	//fmt.Println(string(util.VisualizeSpaces([]byte(sb.String()))))
+	return template.HTML(sb.String())
+}
+
 // Position returns this shortcode's detailed position. Note that this information
 // may be expensive to calculate, so only use this in error situations.
 func (scp *ShortcodeWithPage) Position() text.Position {
@@ -326,7 +347,7 @@ func renderShortcode(
 		hasVariants = hasVariants || more
 	}
 
-	data := &ShortcodeWithPage{Ordinal: sc.ordinal, posOffset: sc.pos, Params: sc.params, Page: newPageForShortcode(p), Parent: parent, Name: sc.name}
+	data := &ShortcodeWithPage{Ordinal: sc.ordinal, posOffset: sc.pos, indentation: sc.indentation, Params: sc.params, Page: newPageForShortcode(p), Parent: parent, Name: sc.name}
 	if sc.params != nil {
 		data.IsNamedParams = reflect.TypeOf(sc.params).Kind() == reflect.Map
 	}

hugolib/shortcode_test.go

@@ -1009,3 +1009,48 @@ echo "foo";
 	b.AssertFileContent("public/p1/index.html", "<pre><code>echo &quot;foo&quot;;\n</code></pre>")
 
 }
+
+func TestShortcodeHighlightIndent(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- config.toml --
+[markup]
+[markup.highlight]
+codeFences = true
+noClasses = false
+-- content/p1.md --
+---
+title: "p1"
+---
+
+## Indent 5 Spaces
+
+     {{< highlight bash >}}
+     line 1;
+     line 2;
+     line 3;
+     {{< /highlight >}}
+
+-- layouts/_default/single.html --
+{{ .Content }}
+`
+
+	b := NewIntegrationTestBuilder(
+		IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+			Running:     true,
+		},
+	).Build()
+
+	fc := b.FileContent("public/p1/index.html")
+
+	fmt.Println(fc)
+
+	b.AssertFileContent("public/p1/index.html", `
+	
+
+	`)
+
+}

tpl/tplimpl/embedded/templates/shortcodes/highlight.html

@@ -1 +1 @@
-{{ if len .Params | eq 2 }}{{ highlight (trim .Inner "\n\r") (.Get 0) (.Get 1) }}{{ else }}{{ highlight (trim .Inner "\n\r") (.Get 0) "" }}{{ end }}
+{{ if len .Params | eq 2 }}{{ highlight (trim .InnerDeindented "\n\r") (.Get 0) (.Get 1) }}{{ else }}{{ highlight (trim .InnerDeindented "\n\r") (.Get 0) "" }}{{ end }}

tpl/tplimpl/template_ast_transformers.go

@@ -272,7 +272,7 @@ func (c *templateContext) collectInner(n *parse.CommandNode) {
 			idents = nt.Ident
 		}
 
-		if c.hasIdent(idents, "Inner") {
+		if c.hasIdent(idents, "Inner") || c.hasIdent(idents, "InnerDeindented") {
 			c.t.parseInfo.IsInner = true
 			break
 		}