What is the difference between enum and shared immutable?

[Ola Fosheim Grøstad]

On Thursday, 29 October 2020 at 14:39:31 UTC, H. S. Teoh wrote:
> On Thu, Oct 29, 2020 at 09:50:28AM -0400, Steven Schveighoffer 
> via Digitalmars-d-learn wrote: [...]
>> D frequently allows no-op attributes.
> [...]
>
> I find that to be a bad smell in terms of language design, 
> actually. Either something should be allowed and have a 
> definite effect, or it should not be allowed.  Not this murky 
> grey area where you can write something and it seems to be 
> allowed, but doesn't actually have any effect.

Yes, but that is a tough call. Do you want to catch unintended 
programmer errors or do you want to make it as easy as possible 
to write generic code? I'm in favour of max strictness, but then 
you need to keep the feature set down and make sure it is uniform 
and orthogonal.

But I think it is a bit sad that "shared" isn't enforced so that 
it could lead to actual benefits. Like requiring that globals are 
typed shared and enable thread local garbage collection. E.g. GC 
allocation of non-shared should be on a thread local heap and 
anything shared should be on a global heap.