DIP 1016--ref T accepts r-values--Community Review Round 1

[Petar]

On Friday, 20 July 2018 at 05:16:53 UTC, Mike Parker wrote:
> This is the feedback thread for the first round of Community 
> Review for DIP 1016, "ref T accepts r-values":
>
> https://github.com/dlang/DIPs/blob/725541d69149bc85a9492f7df07360f8e2948bd7/DIPs/DIP1016.md
>
> All review-related feedback on and discussion of the DIP should 
> occur in this thread. The review period will end at 11:59 PM ET 
> on August 3, or when I make a post declaring it complete.
>
> At the end of Round 1, if further review is deemed necessary, 
> the DIP will be scheduled for another round. Otherwise, it will 
> be queued for the Final Review and Formal Assessment by the 
> language maintainers.
>
> Please familiarize yourself with the documentation for the 
> Community Review before participating.
>
> https://github.com/dlang/DIPs/blob/master/PROCEDURE.md#community-review
>
> Thanks in advance to all who participate.

First of all, I'm very glad to see Manu's persistence turn to 
fruition and by incorporating all the feedback so far, I think we 
have a very solid proposal.

One question:

> It is important that `T` be defined as the argument type [..]

I think this should say that `T` is defined as the *parameter* 
type. This is what I would expect to happen for `void fun(ref int 
x, ref long y, ref double z)`:

```
fun(short(1), byte(2), int(3));
```

=>

```
{
     int    __fun_temp0 = void;
     long   __fun_temp1 = void;
     double __fun_temp2 = void;

     fun(
         __fun_temp0 := short(1),
         __fun_temp1 := byte(2),
         __fun_temp2 := int(3)
     );
}
```

One other subtle point is that the order of declaration of the 
temporaries determines their lifetime, so we must be careful with 
that. In fact I think that we should define it so declaration and 
initialization are not separated and simply make the order of 
declaration match the function argument evaluation order.