DIP74 updated with new protocol for function calls

[Zach the Mystic via Digitalmars-d]

On Sunday, 1 March 2015 at 07:04:09 UTC, Zach the Mystic wrote:
> class RcType {...}
>
> void fun(RcType1 c, RcType1 d);
>
> auto x = new RcType;
>
> fun(x, x);
>
> If the compiler were smart, it would realize that by splitting 
> parameters this way, it's actually adding an additional 
> reference to x. The function should get one x for free, and 
> then force an opAdd/opRelease, for every additional x (or x 
> derivative) it detects in the same call.

One more tidbit:

class RcType {
   RcType r;
   ...
}

void fun(RcType x, RcType y);

auto z = new RcType;
z.r = new RcType;

fun(z, z.r);

 From within fun(), z can alias z.r, but z.r can't possibly alias 
z. Thus, only z.r needs to be preserved. The algorithm should go 
"For each parameter, add one ref/release cycle for every other 
parameter which could possibly generate an alias to it".

We're approaching optimal here. This is feeling good to me.