Why allow initializers of non-static members that allocate?

[matheus]

On Friday, 10 June 2022 at 07:49:43 UTC, Mike Parker wrote:
> ...
> And it *is* documented:
>
>> Struct fields are by default initialized to whatever the 
>> Initializer for the field is, and if none is supplied, to the 
>> default initializer for the field's type.
>> The default initializers are evaluated at compile time.
>
> https://dlang.org/spec/struct.html#default_struct_init

Hmm I understand the text but for this intializers I was 
expecting new address with length 5, for example:

import std.stdio;

struct S{
     int[] arr = new int[](5);
     int[2] arr2;
}

void main(){
     S s1, s2;

     s2.arr[0] = 42;
     writeln(s1.arr[0], " address: ", &s1.arr[0]);
     writeln(s2.arr[0], " address: ", &s2.arr[0]);

     s2.arr2[0] = 10;
     writeln(s1.arr2[0], " address: ", &s1.arr2[0]);
     writeln(s2.arr2[0], " address: ", &s2.arr2[0]);
}

Prints:

42 address: 5586F5BD9CC0
42 address: 5586F5BD9CC0
  0 address: 7FFFC65C7A20
10 address: 7FFFC65C7A40


And as it can be seen: s1.arr and s2.arr shares the same address.

So, in the case of "int[] arr = new int[](5)", an array of length 
5 of type int will be instantiated and its address will be shared 
among whoever instantiates "S" and be pointed and accessed 
through arr.

In the second case, "int[2] arr2", 2 consecutive integer spaces 
in memory will be allocate independently for each "instantiation" 
of "S", so different address.

I never saw this before (I mean I never wrote the first case), 
I'm used to the "int[2] arr2;" way of declaring it, but if I had 
looked this code without knowing this, I'd be certain that s1.arr 
and s2.arr would have different addresses.

This is a bit weird (At least for a newbie like me), I really 
think the compiler should emit an warning about this.

Matheus.