On 07/11/2016 02:54 PM, Steven Schveighoffer wrote:
I think you misunderstand the problem here.
Yes.
Conversion means changing
the type.
Once you have loaded the shared data into a register, or whatever, it's
no longer shared, it's local. Writing it out to another place doesn't
change anything. It's once you add references into the mix where you may
have a problem.
Right.
What I think you mean (and I think you realize this now), is that the
actual copying of the data should not be implicitly allowed. The type
change is fine, it's the physical reading or writing of shared data that
can cause issues. I agree we should extend the rules to prevent this.
Exactly.
In other words:
shared int x;
void main()
{
// ++x; // not allowed
int x2 = x + 1; // but this is
x = x2; // and it shouldn't be
}
I think I would prefer if the compiler would generate atomic operations,
but I'm clearly far from being an expert on any of this. Simply
rejecting the code would be fine with me, too.
Also:
shared int x;
shared int y;
x = y; /* should be rejected too (or be atomic, if that's even possible) */
