On Tuesday, February 27, 2024 at 2:25:46 AM UTC+8 Brien Colwell wrote:
Interesting. That seems to break the comparable spec.
>> Pointer types are comparable. Two pointer values are equal if they point
to the same variable or if both have value nil. Pointers to distinct
zero-size variables may or may not be equal.
>From common sense, this is an obvious bug. But the spec is indeed not clear
enough.
It doesn't state whether or not comparisons of pointers to two distinct
zero-size variables should be consistent in a run session.
Though, from common sense, it should.
>> it would be valid for `==` on pointers to zero-sized types to always
evaluate to `true`,
This would be more straightforward behavior.
On Feb 26, 2024, at 9:24 AM, tapi...@gmail.com <tapi...@gmail.com> wrote:
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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