html/template: remove noescape support

This was never documented or properly implemented.

Fixes #3528.

R=mikesamuel, rsc
CC=golang-dev
https://golang.org/cl/7142048

doc/go1.1.html

@@ -116,6 +116,13 @@ calls the debug/elf functions Symbols or ImportedSymbols may need to be
 adjusted to account for the additional symbol and the change in symbol offsets.
 </p>
 
+<h3 id="html/template">html/template</h3>
+
+<p>
+Templates using the undocumented and only partially implemented
+"noescape" feature will break: that feature was removed.
+</p>
+
 <h3 id="net">net</h3>
 
 <p>

src/pkg/html/template/escape.go

@@ -220,10 +220,7 @@ func ensurePipelineContains(p *parse.PipeNode, s []string) {
 	idents := p.Cmds
 	for i := n - 1; i >= 0; i-- {
 		if cmd := p.Cmds[i]; len(cmd.Args) != 0 {
-			if id, ok := cmd.Args[0].(*parse.IdentifierNode); ok {
-				if id.Ident == "noescape" {
-					return
-				}
+			if _, ok := cmd.Args[0].(*parse.IdentifierNode); ok {
 				continue
 			}
 		}

src/pkg/html/template/escape_test.go

@@ -550,11 +550,6 @@ func TestEscape(t *testing.T) {
 			"<textarea>{{range .A}}{{.}}{{end}}</textarea>",
 			"<textarea>&lt;a&gt;&lt;b&gt;</textarea>",
 		},
-		{
-			"auditable exemption from escaping",
-			"{{range .A}}{{. | noescape}}{{end}}",
-			"<a><b>",
-		},
 		{
 			"No tag injection",
 			`{{"10$"}}<{{"script src,evil.org/pwnd.js"}}...`,
@@ -659,12 +654,6 @@ func TestEscape(t *testing.T) {
 
 	for _, test := range tests {
 		tmpl := New(test.name)
-		// TODO: Move noescape into template/func.go
-		tmpl.Funcs(FuncMap{
-			"noescape": func(a ...interface{}) string {
-				return fmt.Sprint(a...)
-			},
-		})
 		tmpl = Must(tmpl.Parse(test.input))
 		b := new(bytes.Buffer)
 		if err := tmpl.Execute(b, data); err != nil {