nil-struct-pointer.go

package main

import "fmt"

type A struct {
	Name string
}

func (a *A) Go() {
	fmt.Printf("GO: %v\n", a)
}

func Test(fn func()) {
	fn()
}

func main() {
	aa := &A{Name: "FOO"}
	bb := (*A)(nil)
	cc := &A{}
	Test(aa.Go)

	// The variable bb is nil so calling bb.Go() method is expected to cause a panic
	// "runtime error: invalid memory address or nil pointer dereference",
	// but the method call succeeds. Why doesn't this panic?
	Test(bb.Go)

	Test(cc.Go)
}

Output

GO: &{FOO}
GO: <nil>
GO: &{}