DIP 1016--ref T accepts r-values--Formal Assessment

[aliak]

On Friday, 1 February 2019 at 11:48:51 UTC, Timon Gehr wrote:
> On 01.02.19 10:10, aliak wrote:
>>>
>> 
>> Shouldn't doubleMyValue(pt.x) be a compiler error if pt.x is a 
>> getter? For it not to be a compile error pt.x should also have 
>> a setter, in which case the code needs to be lowered to 
>> something else:
>> 
>> {
>>    auto __temp = pt.x;
>>    doubleMyValue(__temp);
>>    pt.x = __temp;
>> }
>> 
>> I believe this is something along the lines of what Swift and 
>> C# do as well.
>> 
>> Or something... a DIP to fix properties anyone? :)
>
> http://wilzbach.github.io/d-dip/DIP24
>
> I'm not sure your rewrite is good though, because it does not 
> preserve aliasing during the function call.

You mean if __temp is modified in the doubleMyValue and pt.x 
aliases something else? Or? Wouldn't the assignment back "just 
work"?

And is there a rewrite that would work then?