Go-switch语句中的重复大小写

Question

I am new to Go, and while attempting to remove some duplicate code across switch statements I added a case with fallthrough like so:

i := 1
switch i {
case 0, 1:
    fmt.Println("common code")
    fallthrough
case 0:
    fmt.Println("aux for 0")
case 1:
    fmt.Println("aux for 1")
default:
    fmt.Println("other number")

}

However, I received an error about the duplicate cases such as:

prog.go:13: duplicate case 0 in switch
    previous case at prog.go:10
prog.go:15: duplicate case 1 in switch
    previous case at prog.go:10

Why is this an error? Is there some way to instruct the compiler to allow such code?

Answer 1

The reason for this behavior, in the current Go, is that the switch is implemented like an if-else-if. Obviously, if (1) else if (1) doesn't make sense, thus you get this error.

Right now, there is no way to force the compiler to do this. You have to rewrite your statements to get the effect you want.

Per this bug report comment supposedly quoting Rob Pike, this restriction will be lifted in a future Go version.