Type Shadowing

What will be printed when the code below is executed? 

  1. package main
  3. import (
  4.     "fmt"
  5. )
  7. type S1 struct{}
  9. func (s1 S1) f() {
  10.     fmt.Println("S1.f()")
  11. }
  12. func (s1 S1) g() {
  13.     fmt.Println("S1.g()")
  14. }
  16. type S2 struct {
  17.     S1
  18. }
  20. func (s2 S2) f() {
  21.     fmt.Println("S2.f()")
  22. }
  24. type I interface {
  25.     f()
  26. }
  28. func printType(i I) {
  29.     fmt.Printf("%T\n", i)
  30.     if s1, ok := i.(S1); ok {
  31.         s1.f()
  32.         s1.g()
  33.     }
  34.     if s2, ok := i.(S2); ok {
  35.         s2.f()
  36.         s2.g()
  37.     }
  38. }
  40. func main() {
  41.     printType(S1{})
  42.     printType(S2{})
  43. }

Answer

  1. main.S1
  2. S1.f()
  3. S1.g()
  4. main.S2
  5. S2.f()
  6. S1.g()