Helping with __mutable (which will be renamed to __metadata)

[Suleyman]

On Monday, 15 April 2019 at 15:59:35 UTC, Timon Gehr wrote:
> At that point, why do you need to slap `immutable` on your type 
> in the first place? Why does your proposed semantics make any 
> sense for reference counting or caching/lazy evaluation?

Otherwise the sole protection from being stored in readonly 
memory is not enough incentive for adding a keyword feature if 
this is the only contribution beyond an unsafe cast then a 
compiler directive should suffice such as pragma(noROM) or 
similar.