nil 1

package main

var x = *new(*int)
var y *int = nil

func f() interface{} {
	return y
}

func main() {
	if f() == nil {
		if x == nil {
			println("A")
		} else {
			println("B")
		}
	} else {
		if x == nil {
			println("C")
		} else {
			println("D")
		}
	}
}

Choices:

• A
• B
• C
• D

Answer: C

Run it on Go play.

Key points:

• An interface value with a nil non-interface dynamic value is not a nil interface. So the function f always return a non-nil interface value.
• A call to the new builtin function always returns a pointer pointing to a zero value. That means dereferencing the pointer results in a zero value. The zero value of the *int type is nil.