Missing Return at End of Function

Why This Happens

Go requires that every code path in a function with a return type ends with a return statement. If you have an if/else block and the compiler cannot prove all paths return, it will emit this error. Placing the return after an if block without an else is a common cause.

The Problem

func abs(n int) int {
    if n < 0 {
        return -n
    }
    // missing return at end of function
}

The Fix

func abs(n int) int {
    if n < 0 {
        return -n
    }
    return n
}

Step-by-Step Fix

1. 1

   Identify the function

   The compiler names the function that is missing a return on some code path.

2. 2

   Trace all code paths

   Walk through every branch (if, switch, for) and verify each one ends with a return.

3. 3

   Add the missing return

   Add a return statement at the end of the function or at the end of each branch that is missing one.