encoding/xml: decode error, such as <foo type="s" tp:type="string">

[jouyouyun]

Please answer these questions before submitting your issue. Thanks!

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

1.8

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

linux 64

What did you do?

test code:

package main

import (
	"encoding/xml"
	"fmt"
	"strings"
)

var xmlData = `
<node>
	<interface name="org.freedesktop.NetworkManager.Device.Gre">
		<signal name="Changed">
			<arg name="changed" type="s"></arg>
		</signal>

		<signal name="PropertiesChanged">
		    <arg name="properties" type="a{sv}" tp:type="String_Variant_Map">
		        <tp:docstring>
		            A dictionary mapping property names to variant boxed values
		        </tp:docstring>
		    </arg>
		</signal>
	</interface>
</node>
`

type NodeInfo struct {
	Interface struct {
		Signals []SignalInfo `xml:"signal"`
	} `xml:"interface"`
}

type SignalInfo struct {
	Name string  `xml:"name,attr"`
	Arg  ArgInfo `xml:"arg"`
}

type ArgInfo struct {
	Name string `xml:"name,attr"`
	Type string `xml:"type,attr"`
}

func main() {
	reader := strings.NewReader(xmlData)
	decoder := xml.NewDecoder(reader)
	var info NodeInfo
	err := decoder.Decode(&info)
	if err != nil {
		fmt.Println("Failed to decode:", err)
		return
	}

	for _, signal := range info.Interface.Signals {
		fmt.Println("Signal:", signal.Name)
		fmt.Printf("\tName: %s\n\tType: %s\n", signal.Arg.Name, signal.Arg.Type)
	}
}

I expected the signal PropertiesChanged 's type to a{sv}, but the result was String_Variant_Map.

What did you expect to see?

I expected the signal PropertiesChanged 's type to a{sv}

What did you see instead?

but the result was String_Variant_Map

[SamWhited]

Duplicate of section 4 on #14407 and, more specifically, of #8535; let's track this there. Thanks!