Calls `this(this)` extra with delegate stuff in the code

[Ali Çehreli via Digitalmars-d-learn]

Simplified:

import std.stdio;

struct Widget {
     private int[] array;
     this(uint length) {
         array = new int[length];
         writefln("ctor called      : %s", array.ptr);
     }
     this(this) {
         writef( "this(this) called: %s", array.ptr );
         array = array.dup;
         writefln(" -> %s", array.ptr);
     }
}

void main() {
     auto w1 = Widget(10);
     writeln(w1);
}

It's due to the copies that are made when calling writeln and other 
functions that it calls.

Ali