net/url: should *User methods return zero values when called with a nil receiver?

[kindlychung]

Please answer these questions before submitting your issue. Thanks!

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

go version go1.8.1 linux/amd64

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

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/kaiyin/go"
GORACE=""
GOROOT="/usr/lib/go-1.8"
GOTOOLDIR="/usr/lib/go-1.8/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build230264726=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"

What did you do?

https://play.golang.org/p/3yO2OL-XTq

What did you expect to see?

I would like to have something like username, err := url.User.Username() and handle the error if there is no username in the url.

What did you see instead?

A panic.

[bradfitz]

I could see some argument for (*Userinfo).Password and (*Userinfo).Username to return zero values when called with a nil receiver instead of panicking.

Leaving open to decide during Go 1.10.

[bradfitz]

That is, we could make this work:

https://play.golang.org/p/Hf78MQCh6o

package main

import "net/url"

func main() {
	u, err := url.Parse("http://foo.com/")
	if err != nil {
		panic(err)
	}
	println("URL username is ...")
	println(u.User.Username())
}

[gopherbot]

CL https://golang.org/cl/47851 mentions this issue.

[bradfitz]

Has CL, so added release-blocked label.

[bradfitz]

@rsc, thoughts? I'm fine with this but don't feel strongly.