Go Tip

Lets say you have a function:

func ShouldNotReachHere() {
    panic("should not reach here")
}

And you try to use it like:

func Fn(x int) int {
    switch x {
    case 1:
        ... return ...
    case 2:
        ... return ...
    default:
        ShouldNotReachHere()
    }
}

Unfortunately, that won't work. You'll get a "missing return" error when you try to compile. That's because the compiler doesn't know that ShouldNotReachHere never returns. (Actually, it does know that when it's compiling ShouldNotReachHere, but it doesn't keep track of that information.) C++ has [[noreturn]] to specify that but currently Go doesn't have an equivalent.

You could add a dummy return statement but I find that misleading since it will never actually return anything.

What I tend to do is add a dummy return type to ShouldNotReachHere (it's not critical what type since you're not actually using it).

func ShouldNotReachHere() int {
    panic("should not reach here")
}

and then use it like:

panic(ShouldNotReachHere())

If that was the only way you used it, then ShouldNotReachHere could just be a string constant. But defining it this way means you're not forced to use panic. (And if it was a function returning the string, then you could forget to use panic.)