Is "auto t=T();" not the same as "T t;"?

[Andrey Zherikov]

On Tuesday, 25 October 2022 at 14:53:50 UTC, Adam D Ruppe wrote:
> On Tuesday, 25 October 2022 at 13:51:30 UTC, Andrey Zherikov 
> wrote:
>>     A[] a = [A.init];
>
> This is a problem - this is referring to a static array 
> instance, shared across all copies of B. You almost certainly 
> don't want this.
>
> That B.a[0] is the *same object* across different 
> default-constructed Bs... unless the optimizer hits it or 
> something.

Is it a bad idea to trigger copy on write before modification of 
B.a so it behaves as below?
```d
     B b1;
     b1.a = b1.a.dup;   // copy on write
     b1.a[0].i ~= '1';
     b1.a ~= A.init;
     b1.a[0].i ~= '2';
     b1.a[1].i ~= '3';
     b1.writeln;        // B([A("12"), A("3")])

     B b2;
     b2.writeln;        // B([A("")])
```