Parameters declared as the alias of a template won't accept the arguments of the same type.

[Elfstone]

On Sunday, 1 May 2022 at 06:42:26 UTC, Tejas wrote:
> On Sunday, 1 May 2022 at 03:57:12 UTC, Elfstone wrote:
>>     module test;
>>
>>     struct MatrixImpl(S, size_t M, size_t N)
>>     {
>>     }
>>
>> [...]
>
> AFAICT, I'm afraid you'll have to stick to `dot2` 🙁
>
>
> This DIP I believe does what you want but... It wasn't looked 
> upon favorably...
>
> https://github.com/dlang/DIPs/blob/master/DIPs/other/DIP1023.md

Thanks a lot! So this really is a D "feature".
The current behaviour is so broken. It makes no sense, for a 
language user at least.
I don't understand why it's not yet solved, if it's a known issue.