auto ref is on the docket

[via Digitalmars-d]

On Tuesday, 23 June 2015 at 12:45:25 UTC, kink wrote:
> On Tuesday, 23 June 2015 at 09:57:26 UTC, Marc Schütz wrote:
>> To guarantee this from the caller's POV, the callee must be 
>> pure and the parameters must be known not to alias each other.
>
> This is obviously true. Rvalues aren't affected as they cannot 
> alias another parameter by definition.

You're right, I didn't think of that! They are not _transitively_ 
unique, but there can indeed be no other references to the 
rvalues themselves. So for rvalues, const is enough. Nice :-)

> Lvalues are if passed by ref and the same instance is 
> accessible by mutable ref from another parameter or global. But 
> as shown by your example, that danger is always there. The 
> proposed `in` semantics make it less obvious, that's true, but 
> I still think it'd be worth it, as these aliasing bugs are a 
> pain to track down, but in my experience extremely rare.