Any differnece between value types and reference types for =sink ?

[zbzpo2002]

Description

import strutils
type 
    Person = object
       name: string
       age: int       
    Personobj = ref Person

proc `=destroy`(x: var Person) =
    var address = cast[int](addr x).toHex
    echo x.name & " with address " & address & " object was destroyed!"    

proc `=sink`(dest: var Person; source: Person) =
   echo "sink starts"
   `=destroy`(dest)
   wasMoved(dest)   
   echo "sink ends"

proc `=copy`(dest: var Person; source: Person){.error.} =
    echo "copy hook"
    if dest.name != source.name :
       dest.name = source.name
       dest.age = source.age
    echo "copy hook end"

proc `=wasMoved`(x: var Person) =    
    x.name = "empty111"
    x.age = 0

proc main() =   
    let a1  = Person(name:"a1", age: 20)  
    var a2  = Person(name:"a2", age: 21)        
    var a1address = cast[int](addr a1).toHex   
    var a2address = cast[int](addr a2).toHex
    echo "a1.address = " & a1address
    echo "a2.address = " & a2address      
    a2 = a1
    echo "program end====="
main()

For a value type, Nim compier will call destructor twice, I wonder whether it's designed behaviour ？ if yes, why ref object calls =destry once ?

Nim Version

Nim Compiler Version 2.1.1 [Windows: amd64]
Compiled at 2024-05-18
Copyright (c) 2006-2024 by Andreas Rumpf

active boot switches: -d:release

Current Output

a1.address = 000000DE975FF590
a2.address = 000000DE975FF570
sink starts
a2 with address 000000DE975FF570 object was destroyed!
sink ends
program end=====
 with address 000000DE975FF570 object was destroyed!
empty111 with address 000000DE975FF590 object was destroyed!

Expected Output

a1.address = 000000DE975FF590
a2.address = 000000DE975FF570
sink starts
a2 with address 000000DE975FF570 object was destroyed!
sink ends
program end=====
empty111 with address 000000DE975FF590 object was destroyed!

Possible Solution

n/a

Additional Information

n/a

[Araq]

No bug here, you need to check for the "wasMoved" state inside your destructor. The manual is pretty clear about this.