Does `is` expression with template alias need fixing.

[zjh]

On Wednesday, 22 March 2023 at 10:43:15 UTC, Elfstone wrote:
> ```C++
> template <typename T>
> using Vector3 = Matrix<T, 3, 1>;
> ```
>
> I declare an alias and I use it everywhere. It acts as a 
> natural constraint. I never needed `isVector3` with my old C++ 
> code. I expected D could do the same, and was really frustrated 
> when I found out it couldn't. Even more frustrated when I read 
> Steven's reply, that the bug with `is` has been there for 16 
> years.
>

When you have questions, please file a bugzilla.
D is only for `specific problems`, please describe the problem 
carefully.