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

[Paul Backus]

On Tuesday, 25 October 2022 at 17:54:16 UTC, Salih Dincer wrote:
> On Tuesday, 25 October 2022 at 17:18:35 UTC, Paul Backus wrote:
>> It's not a bug. They're pointing to the exact same instance of 
>> `A` in memory:
>
> I don't understand?  So I don't understand why it causes 
> problems with dynamic arrays!  So why is there nothing wrong 
> with the static array in the example below?

Static arrays are value types. When you copy a static array, the 
copy's data is stored in a separate block of memory from the 
original:

```d
int[1] a = [1];
int[1] b = a;

assert(&a[0] !is &b[0]); // different memory
```

Dynamic arrays are reference types. When you copy a dynamic 
array, both copies point to the same block of memory:

```d
int[] a = [1];
int[] b = a;

assert(&a[0] is &b[0]); // same memory
```

In order to create a copy of a static array with its own block of 
memory, separate from the original, you have to use the built-in 
`.dup` method:

```d
int[] a = [1];
int[] b = a.dup;

assert(&a[0] !is &b[0]); // different memory
```