Non-recursive maxSizeOf

[Per Nordlöw]

On Thursday, 6 August 2020 at 13:07:14 UTC, Per Nordlöw wrote:
> Do you have any simple solution to this, H. S. Teoh?

I also tried

template maxSize(Ts...)
{
     align(1) union Impl
     {
         // See_Also: 
https://forum.dlang.org/thread/wbpnncxepehgcswhuazl@forum.dlang.org?page=1
         static foreach (T; Ts)
         {
             static if (!is(T == void))
             {
                 pragma(msg, T.stringof ~ " _store" ~ T.mangleof ~ 
";");
                 mixin(T.stringof ~ " _store" ~ T.mangleof ~ ";");
             }
         }
     }
  	enum maxSize = Impl.sizeof;
}

but that fails because of types not being defined in scope such as

Cat _storeS3std7variant17__unittest_L96_C7FNfZ3Cat;
/home/per/Work/phobos/std/variant.d-mixin-88(88,5): Error: 
undefined identifier `Cat`


Can somebody find a better alternative?