text/template: add CommentNode to template parse tree

Fixes #34652

Change-Id: Icf6e3eda593fed826736f34f95a9d66f5450cc98
Reviewed-on: https://go-review.googlesource.com/c/go/+/229398
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>

2 files changed, 18 insertions, 0 deletions

diff --git a/src/html/template/escape.go b/src/html/template/escape.go
index f12dafa870..8739735cb7 100644
--- a/src/html/template/escape.go
+++ b/src/html/template/escape.go
@@ -124,6 +124,8 @@ func (e *escaper) escape(c context, n parse.Node) context {
 	switch n := n.(type) {
 	case *parse.ActionNode:
 		return e.escapeAction(c, n)
+	case *parse.CommentNode:
+		return c
 	case *parse.IfNode:
 		return e.escapeBranch(c, &n.BranchNode, "if")
 	case *parse.ListNode:
diff --git a/src/html/template/template_test.go b/src/html/template/template_test.go
index 86bd4db444..1f2c888bbe 100644
--- a/src/html/template/template_test.go
+++ b/src/html/template/template_test.go
@@ -10,6 +10,7 @@ import (
 	. "html/template"
 	"strings"
 	"testing"
+	"text/template/parse"
 )
 
 func TestTemplateClone(t *testing.T) {
@@ -160,6 +161,21 @@ func TestStringsInScriptsWithJsonContentTypeAreCorrectlyEscaped(t *testing.T) {
 	}
 }
 
+func TestSkipEscapeComments(t *testing.T) {
+	c := newTestCase(t)
+	tr := parse.New("root")
+	tr.Mode = parse.ParseComments
+	newT, err := tr.Parse("{{/* A comment */}}{{ 1 }}{{/* Another comment */}}", "", "", make(map[string]*parse.Tree))
+	if err != nil {
+		t.Fatalf("Cannot parse template text: %v", err)
+	}
+	c.root, err = c.root.AddParseTree("root", newT)
+	if err != nil {
+		t.Fatalf("Cannot add parse tree to template: %v", err)
+	}
+	c.mustExecute(c.root, nil, "1")
+}
+
 type testCase struct {
 	t    *testing.T
 	root *Template