Label Defined and Not Used

Why This Happens

Go labels must be used by at least one goto, break, or continue statement. If you define a label and never reference it, the compiler treats it as an error. Labels are typically used to break out of nested loops.

The Problem

func main() {
outerLoop: // defined but not used
    for i := 0; i < 10; i++ {
        for j := 0; j < 10; j++ {
            if j == 5 {
                break
            }
        }
    }
}

The Fix

func main() {
outerLoop:
    for i := 0; i < 10; i++ {
        for j := 0; j < 10; j++ {
            if j == 5 {
                break outerLoop
            }
        }
    }
}

Step-by-Step Fix

1. 1

   Identify the unused label

   Find the label the compiler says is unused.

2. 2

   Decide if it is needed

   Determine if you need the label for nested loop control or if it was left over from refactoring.

3. 3

   Use or remove

   Either add break/continue with the label name, or remove the label entirely.