package main
var a, b [0]int
var p, q = &a, &b
func main() {
if (p == q) {
p, q = &a, &b
println(p == q) // false
}
}
On Thursday, February 22, 2024 at 6:55:49 PM UTC+8 Brien Colwell wrote:
> I'm confused by this output. It appears that the interface of two
> different pointers to an empty struct are equal. In all other cases,
> interface equality seems to be the pointer equality. What's going on in the
> empty struct case?
>
> ```
> package main
>
> import "fmt"
>
> type Foo struct {
> }
>
> func (self *Foo) Hello() {
> }
>
> type FooWithValue struct {
> A int
> }
>
> func (self *FooWithValue) Hello() {
> }
>
> type Bar interface {
> Hello()
> }
>
> func main() {
> a := &Foo{}
> b := &Foo{}
> fmt.Printf("%t\n", *a == *b)
> fmt.Printf("%t\n", a == b)
> fmt.Printf("%t\n", Bar(a) == Bar(b))
>
> c := &FooWithValue{A: 1}
> d := &FooWithValue{A: 1}
> fmt.Printf("%t\n", *c == *d)
> fmt.Printf("%t\n", c == d)
> fmt.Printf("%t\n", Bar(c) == Bar(d))
> }
> ```
>
> Prints (emphasis added on the strange case):
>
> ```
> true
> false
> **true**
> true
> false
> false
> ```
>
>
>
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