Demonstrate named return masking

mask_return.go

package main

import "fmt"

/* OUTPUT:
[named] defer: foo error
[main] named err: foo error
[var] defer: <nil>
[main] var err: foo error
*/

func main() {
	fmt.Printf("[main] named err: %v\n", namedReturn())
	fmt.Printf("[main] var err: %v\n", varErr())
}

func namedReturn() (err error) {
	defer func() {
		fmt.Printf("[named] defer: %v\n", err)
	}()

	{
		err := fmt.Errorf("foo error")
		return err
	}
}

func varErr() error {
	var err error
	defer func() {
		fmt.Printf("[var] defer: %v\n", err)
	}()

	{
		err := fmt.Errorf("foo error")
		return err
	}
}