Declared and Not Used

Why This Happens

Go requires every declared variable to be used at least once. This is a compile-time error that enforces clean code. The blank identifier _ can be used to discard values you intentionally do not need, such as one return value from a multi-return function.

The Problem

func main() {
    x := 42
    y := 10
    fmt.Println(y)
    // x declared and not used
}

The Fix

func main() {
    _ = 42 // discard if not needed
    y := 10
    fmt.Println(y)
}

Step-by-Step Fix

1. 1

   Identify the unused variable

   The compiler message tells you exactly which variable is unused and on which line.

2. 2

   Decide if it is needed

   If the variable is not needed, remove the declaration entirely.

3. 3

   Use blank identifier if needed

   If you must call the function but do not need the result, assign to _ instead.