encoding/xml: decoding XML with entities not supported

[kunalgrover05]

What version of Go are you using (go version)?

$ go version
1.9

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

Linux AMD64

go env Output

$ go env

What did you do?

XML entity support

	s := "<?xml version='1.0' encoding='ISO-8859-1'?><!DOCTYPE foo [ <!ENTITY test 'hello' > ]><Users><User><Name>&test;</Name></User></Users>"

	reader := strings.NewReader(s)
	decoder := xml.NewDecoder(reader)
	decoder.CharsetReader = charset.NewReaderLabel

	for {
		token, err := decoder.Token()
		if err != nil && err != io.EOF {
			fmt.Printf("Error! Decoding XML failed: %v\n", err)
			break
		}
		if token == nil {
			break
		}
		switch element := token.(type) {
		case xml.CharData:
			fmt.Printf("%s\n", element)
		}
	}

Exception

Error! Decoding XML failed: XML syntax error on line 1: invalid character entity &test;

Parsed data with decoder.Strict = false

&pwnd;

What did you expect to see?

Entities and External entities to be processed as per https://www.w3.org/TR/xml/#sec-entity-decl

What did you see instead?

[mvdan]

I'm not experienced with XML, but have you had a look at #4196? And possibly #20614 too, since I see some extra whitespace in there.

[gopherbot]

Timed out in state WaitingForInfo. Closing.

(I am just a bot, though. Please speak up if this is a mistake or you have the requested information.)