encoding/xml: It does not read correctly the field tag from xml.Name when it unmarshals an XML from a string

[rm4n0s]

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

go version go1.20.1 linux/amd64

Does this issue reproduce with the latest release?

Yes

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

go env Output

GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/job/.cache/go-build"
GOENV="/home/job/.config/go/env"
GOEXE=""
GOEXPERIMENT="arenas"
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/job/go-projects/pkg/mod"
GONOPROXY="*"
GONOSUMDB="*"
GOOS="linux"
GOPATH="/home/job/go-projects"
GOPRIVATE="*"
GOPROXY="direct"
GOROOT="/home/job/bin/go"
GOSUMDB="off"
GOTMPDIR=""
GOTOOLDIR="/home/job/bin/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.20.1"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/job/go-projects/work/smsgw3/go.mod"
GOWORK=""
CGO_CFLAGS="-O2 -g"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-O2 -g"
CGO_FFLAGS="-O2 -g"
CGO_LDFLAGS="-O2 -g"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build1489430774=/tmp/go-build -gno-record-gcc-switches"

What did you do?

Tried to xml.Unmarshal a specific XML in a string format and it through an error.
Here is the link to the code https://go.dev/play/p/-eFryHvZ-0E

What did you expect to see?

I expected no error.

What did you see instead?

This error

expected element type <soapenv:Envelope> but have <Envelope>

It is like the xml.Unmarshal does not read the field tag of the XMLName.

[rm4n0s]

This package github.com/nbio/xml seems to resolve the problem

Can you replicate the solution?

[heschi]

cc @rsc

[seankhliao]

https://pkg.go.dev/encoding/xml#Name

A Name represents an XML name (Local) annotated with a name space identifier (Space). In tokens returned by Decoder.Token, the Space identifier is given as a canonical URL, not the short prefix used in the document being parsed.

The correct usage would be:

	XMLName                xml.Name `xml:"http://schemas.xmlsoap.org/soap/envelope/ Envelope"`

https://go.dev/play/p/WpKyJ8E0wCd

or without the namespace.

[rm4n0s]

Hi @seankhliao,
Looking at the results from https://go.dev/play/p/WpKyJ8E0wCd the EnvelopeNamespace, ShemaNamespace, and ShemaInstanceNamespace are empty.
These fields should not be empty.
Here is the same example and only replacing encoding/xml with github.com/nbio/xml https://go.dev/play/p/pUaXJ-l0ElK

[seankhliao]

There are a lot of issues with namespaces, see #13400

but if you just want to unmarshal it, it's sufficient to drop the namespace
https://go.dev/play/p/9Q2ze_8WWIU

[rm4n0s]

It seems this project https://github.com/nbio/xml solves all the problems that listed on #13400, why not copy-paste its solutions to encoding/xml?