Nice. But because this is not a regression, there's no time (or risk) budget for Go 1.9, due out shortly.

I think this is correct behavior. If you print v.Type().String(), you will see that it has type interface {}. Interface types are comparable. It just happens that this interface value holds a value that can not be compared.

In other words, this is approximately equivalent to

package main

func main() {
	var i interface{} = func() { println("Hello world") }
	println(i == i)
}

which will also panic.

Whoops, I overlooked the type interface {} after "var i".

I agree this looks fine.

That's fine, but if interface{} is comparable, why can't I use it in the map then?

Also everything works as expected if I remove pointer: v := reflect.Indirect(reflect.ValueOf(_&_i))

You can use an interface{} in a map.

What you can't do is use an interface{} in a map if you store a func value in the interface.

If you remove the pointer, then the value you get in v has type func(), which is not comparable. In both cases, try printing v.Type().String() to see what is going on.

Thanks! I think I've misunderstood, what Interface() returns:

// Special case: return the element inside the interface.
// Empty interface has one layout, all interfaces with
// methods have a second layout.