This code

==========
import std.variant;

Variant v = "hello";

void main()
{
}
==========

results in this error:

/usr/local/include/dmd/std/variant.d(624): Error: memcpy cannot be interpreted at compile time, because it has no available source code
/usr/local/include/dmd/std/variant.d(559):        called from here: this.opAssign(value)
q.d(3):        called from here: VariantN(& handler, cast(ubyte)0u, ).this("hello")

I would _think_ that it could be made to work without memcpy, but I don't know. Regardless, the use of memcpy restricts the ability to use Variant at compile time. So ideally, Variant would be fixed so that the example here worked.