reflect.Select: behavior when called with an empty slice of cases

[AndreyNevolin]

Please answer these questions before submitting your issue. Thanks!

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

1.9.1

Does this issue reproduce with the latest release?

Don't know

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

GOHOSTARCH="amd64"
GOHOSTOS="linux"

What did you do?

active_index, rcv_value, ok := reflect.Select(make([]reflect.SelectCase, 0))

If possible, provide a recipe for reproducing the error.
A complete runnable program is good.
A link on play.golang.org is best.
package main

import "reflect"
import "fmt"

func main() {
active_index, rcv_value, ok := reflect.Select(make([]reflect.SelectCase, 0))
fmt.Println(active_index, rcv_value, ok)
}

What did you expect to see?

I don't know. The behavior of "reflect.Select" called with an empty slice is not documented anywhere as I can judge.
I would prefer the call to return an error. But I don't know what is the intended behavior. Maybe the developers consider "hanging forever" behavior the right option.

Please consider changing or documenting the behavior of "reflect.Select" called with an empty slice.

What did you see instead?

The following message:
fatal error: all goroutines are asleep - deadlock!

This is documented in the reflect.Select call:

Like the Go select statement, it blocks until at least one of the cases can proceed

Since there are no cases, it blocks forever. You get the same result when doing the following:

select {}

[ianlancetaylor]

The intent is that reflect.Select act like the select statement. I think that is what it does, and it is documented that way. Closing because I don't think there is anything to do.