I wish all qualifiers were revisited with an eye for simplification

[IGotD-]

On Sunday, 2 August 2020 at 20:50:14 UTC, Andrei Alexandrescu 
wrote:
>
> * Nobody - probably not even Timon - knows what "shared" does 
> or is supposed to do and not do. The most I got from Walter 
> ever is "shared is intentionally restricted so you can't do 
> much without a cast". Yet the definition of "much" and the 
> conditions under which casting is legit are not anywhere to be 
> found.
>

Shouldn't shared just be a relaxation in compiler checks so that 
any data that has the "shared" qualifier is allowed to be shared 
between threads. This is pretty much what __gshared is about. For 
the compiler to check if you really can share the data is 
currently impossible with current compiler technology. It can be 
atomic integers, Intel TSX, some very elaborate lockless 
algorithm, lockless COW, even mutexes/spinlocks if necessary. 
Programmer must "manually" ensure that the data can be shared, 
there is no other way.

So yes, a revisit of the qualifiers should be done so that they 
can be precisely defined.