Does a mutating struct function in swift create a new copy of self?

Question

I like value semantics in swift but I am worried about the performance of mutating functions. Suppose we have the following struct

struct Point          


        

Answer 1

I did this:

import Foundation

struct Point {
  var x = 0.0
  mutating func add(_ t:Double){
    x += t
  }
}

var p = Point()

withUnsafePointer(to: &p) {
  print("\(p) has address: \($0)")
}

p.add(1)

withUnsafePointer(to: &p) {
  print("\(p) has address: \($0)")
}

and obtained in output:

Point(x: 0.0) has address: 0x000000010fc2fb80

Point(x: 1.0) has address: 0x000000010fc2fb80

Considering the memory address has not changed, I bet the struct was mutated, not replaced.

To replace completely something, you have to use another memory address, so it's pointless to copy back the object in the original memory address.