Second draft: Sum Type by Struct

[Per Nordlöw]

On Friday, 11 September 2026 at 22:12:16 UTC, Richard (Rikki) 
Andrew Cattermole wrote:
> On 12/09/2026 10:07 AM, Per Nordlöw wrote:
>> On Thursday, 10 September 2026 at 17:56:21 UTC, Richard 
>> (Rikki) Andrew Cattermole wrote:
>>> No.
>> 
>> Can you please give a motive to why you don't want to support 
>> this? And I don't understand why you are pasting the code 
>> failure. The code works for me.
> Bit packing requires assumptions.

And how is that blocker? The optimization could kick only when 
the alignment of the pointed to types give room to tag bits which 
is often the case for struct types.

> The bottom bits are used, it is not a modulas of a the type 
> size.

For what values of `Types` passed to my `GCWordVariant` are you 
referring to here?