Nested Classes with inheritance

[user1234]

On Saturday, 19 March 2022 at 00:05:54 UTC, Salih Dincer wrote:
> Greetings to all...
>
> There are nested classes as below. But beware, there's also 
> inheritance, extra! If you construct ```Bar b``` from main(), 
> it's okay. But if declare the constructor in Foo(), the program 
> crashes with a segmentation error.
>
> Is this not legal? Like two mirrors are facing each other, that 
> I do?
>
> ```d
> class Foo
> {
>     Bar b;
>     int i;
>
>     this(int n)
>     {
>         this.i = n;
>         //this.b = new Bar(this.i); // compiles but crashes
>     }
>
>     class Bar : Foo
>     {
>         int i;
>
>         this(int n)
>         {
>             this.i = n;
>             super(this.i);
>         }
>
>     }
> }
>
> void main()
> {
>     auto foo = new Foo(1);
>     auto bar = foo.new Bar(1);
>     foo.b = bar;
>
>     assert(foo.i == foo.b.i);
> }
> ```
> SDB at 79

That crashes because of the creation of `Bar b` member, which 
itself has a Bar b member, which itself...

One solution is to create the member depending on some condition, 
example:

```d
if (typeid(this) !is typeid(Bar))
     this.b = new Bar(this.i);
```