why static array can be reassigned with new allocation?

[mw]

On Sunday, 16 October 2022 at 09:04:59 UTC, Nick Treleaven wrote:
> On Sunday, 16 October 2022 at 01:54:51 UTC, mw wrote:
>> On Sunday, 16 October 2022 at 00:27:56 UTC, Paul Backus wrote:
>>>
>>> Static arrays can be reassigned, though:
>>>
>>>     int[3] a = [1, 2, 3];
>>>     int[3] b = [4, 5, 6];
>>>     b = a;
>>>     a[0] = 4;
>>>     assert(b == [1, 2, 3]);
>>
>> From the context of this discussion thread, "var reassign" to 
>> static array means: change a.ptr to where it pointing to, i.e 
>> the address. And "content assignment" means: change the 
>> content of the array (but not the a.ptr, the address).
>
> A static array doesn't have a ptr runtime field.

Someone showed this code very earlier in this thread already:


void main() {
      int[3] arr;
      writeln(arr.ptr);
}

Output:
7FFC1A072820


>> You example here is "content assignment".
>>
>> My main point is these two different assignments shouldn't use 
>> the same syntax, regardless they are static or dynamic array.
>
> There is no problem with assigning a static array to another, 
> because the lengths are always checked at compile time.

Not in my OP example.

> A static array is a value type so assignment needs to be 
> supported for generic code.

That is not excuse to mix two different semantics into one syntax.

Especially D has `static if`.