Calling a method with a pointer receiver by an object instead of a pointer to it?

v is an object of Vertex, and Scale is a method for a pointer to Vertex. Then why is v.Scale(10) not wrong, given that v isn't a pointer to a Vertex object? Thanks.

package main
import (
	"fmt"
	"math"
)
type Vertex struct {
	X, Y float64
}
func (v Vertex) Abs() float64 {
	return math.Sqrt(v.X*v.X + v.Y*v.Y)
}
func (v *Vertex) Scale(f float64) {
	v.X = v.X * f
	v.Y = v.Y * f
}
func main() {
	v := Vertex{3, 4}
	v.Scale(10)
	fmt.Println(v.Abs())
}

Spec: Calls:

> A method call x.m() is valid if the method set of (the type of) x contains m and the argument list can be assigned to the parameter list of m. If x is addressable and &x's method set contains m, x.m() is shorthand for (&x).m().

The compiler sees that Scale() has a pointer receiver and also that v is addressable (as it is a local variable), so v.Scale(10) will be interpreted as (&v).Scale(10).

This is just one of the many conveniences the spec offers you so the source code can remain clean.

It's the Go automatic dereferencing:

From https://golang.org/ref/spec#Method_values:

>As with selectors, a reference to a non-interface method with a value receiver using a pointer will automatically dereference that pointer: pt.Mv is equivalent to (*pt).Mv.