Hi gophers,
I’m learning to read panic messages. As far as I know, a string is passed in as a pointer to data and a length, a struct is spread out. However when I testing around with the following code, there’s a 0x1 at the end of func hey. When I give it a filed z and value, it changes to that value. What does it mean and why is this?
playground
package main
import (
"fmt"
"unsafe"
)
type Nil int
func (n *Nil) hello() {
fmt.Println(*n)
panic("no no no")
}
type A struct {
x string
y *Nil
//z int
}
func main() {
var a A
a.x = "string"
none := Nil(2)
a.y = &none
//a.z = 3
fmt.Println(unsafe.Sizeof(a))
hey(a)
}
func hey(a A) {
a.y.hello()
}
12
2
panic: no no no
goroutine 1 [running]:
main.(*Nil).hello(...)
/tmp/sandbox662940585/prog.go:12
main.hey(0x115e1c, 0x6, 0x41a784, 0x1)
/tmp/sandbox662940585/prog.go:32 +0xc0
main.main()
/tmp/sandbox662940585/prog.go:28 +0xa0
Program exited: status 2.