Typefunctions: alias[] can now be transformed to tuple

[Stefan Koch]

On Tuesday, 6 October 2020 at 13:31:05 UTC, Nick Treleaven wrote:
> On Tuesday, 6 October 2020 at 09:01:00 UTC, Stefan Koch wrote:
>> I always intended to have type function returns transform 
>> themselves automatically into tuples when they are leaving the 
>> last level of CTFE calls, but that's not only tricky to 
>> implement, that's also a rather bad idea ;)
>
> Is it tricky because functions can't return tuples? Why would 
> it be a bad idea? Just curious.
>
> Also should an alias sequence (type tuple) implicitly convert 
> to an alias[]? I expect that would require copying too.

Actually it does not require copying.
Internally I create a new node and put in a link to an existing 
sub-tree.

auto ae = e.isArrayLiteralExp();
return new TupleExp(e.loc, ae.elements);
done :)

It's a bad idea because then I would have unrolled foreachs again.
And worse the type system would lie.