[dmd-concurrency] tail-shared by default?

[Walter Bright]

Steve Schveighoffer wrote:
>
> It's too bad that tail-const wouldn't work.  I don't think tail-shared presents the same problems.  Please don't dismiss all the points I wrote just because of past failures.  They are new ideas that don't apply to const at all.
>
>   

They do apply. It is not about the semantic difference between const and 
shared, it is about the question "is this expression shared or not 
shared? const or not const?" How do I declare a type to be tail-shared? 
tail-const? Those questions must be unambiguously answered before you 
can apply semantics.

In this context, tail-shared and tail-const are exactly the same problem.