Gopherjs: `go close(ch)` causes compile error

[hajimehoshi]

http://www.gopherjs.org/play/#/uhMTBoBe53

angular.js:9937 Error: Unhandled object: *types.Builtin

[neelance]

Is there any semantic difference between go close(ch) and close(ch)?
/cc @shurcooL

[hajimehoshi]

In GopherJS, callbacks should not be blocked by e.g. close and in this case go is necessary. BTW, go func() { close(ch) }() worked.

[neelance]

close should not be considered as blocking. If it is, then that's a bug.

[hajimehoshi]

Ah, I was misunderstanding. Thanks. go close(ch) should be compiled without errors anyway.

[dmitshur]

close should not be blocking indeed.

Is there any semantic difference between go close(ch) and close(ch)?

Yes, there is. Consider:

ch := make(chan struct{})
close(ch)
select {
case <-ch:
    fmt.Println("a")
default:
    fmt.Println("b")
}

That program is always going to output "a" only. But if you use go close(ch), it will print "a" or "b".

[dominikh]

In the context of GopherJS, however, it should be save to transform go close(ch) to close(ch). That's a valid way of scheduling the operation.

Do note that there are other built-ins that probably fail compilation right now, such as go delete(...)