flag: ContinueOnError is not continuing

[curlup]

Please answer these questions before submitting your issue. Thanks!

1. What version of Go are you using (go version)?
   go1.4.2 linux/amd64
2. What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOCHAR="6"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="~/gocode"
GORACE=""
GOROOT="~/code/go"
GOTOOLDIR="~/code/go/pkg/tool/linux_amd64"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0"
CXX="g++"
CGO_ENABLED="1"

1. What did you do?

fs := flag.NewFlagSet("d", flag.ContinueOnError)
boolPtr := fs.Bool("fork", false, "a bool")
_ = fs.Parse([]string{"-unknown", "--fork"})

https://play.golang.org/p/93DWNF-53z

1. What did you expect to see?
   fork: true because ContinueOnError is used
2. What did you see instead?

flag provided but not defined: -unknown
Usage of d:
  -fork
        a bool
fork: false

I didn't expect to see Usage though

[martinlindhe]

flag.ContinueOnError says "Return a descriptive error" [1]
Additionally, the 2nd parameter to fs.Bool() is the default value to use. Since you set it to false, that will be the value of *boolPtr [2]

Finally, it is continuing, as your go playground link demonstrates by printing the last line "fork: false"

1: https://golang.org/src/flag/flag.go?s=6739:6761#L259
2: https://play.golang.org/p/7QJz9r6lo_

[ianlancetaylor]

I think this is working as intended. Certainly we are not going to change the behavior. If you have a specific suggestion for how to improve the docs, please let us know. Closing.