On Friday, 10 April 2015 at 10:02:01 UTC, Martin Nowak wrote:
On Wednesday, 8 April 2015 at 23:11:08 UTC, Walter Bright wrote:
http://wiki.dlang.org/DIP77
So someone passes an RCO via ref to avoid the inc/dec, and
because that imposes safety issues we turn it into some sort of
pass by value under the hood, defeating the purpose, and
provide an opt-out via @system opAssign.
Wouldn't it more straightforward to make pass-by-ref unsafe
(@system) for RCOs?
Then the only thing missing to make this equally powerful,
would be an optimization opportunity for the compiler to elide
copies of pass-by-value RCOs, e.g. it could avoid calling the
postblit when the function retains the refcount.
Only the first pass by ref create a copy. You can then pass the
ref down all you want without copy.
That is an acceptable cost IMO.
