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

Olivier FAURE couteaubleu at gmail.com
Thu Jan 31 16:04:27 UTC 2019

On Thursday, 31 January 2019 at 02:10:05 UTC, Manu wrote:
> I still can't see a truck-sized hole.

I don't know if it's truck-sized, but here's another corner case:

     int doubleMyValue(ref int x) {
         x *= 2;
         return x;

     Point pt;
     pt.x = 5;
     pt.y = foobar();

     assert(pt.x == 10);

Question: in the above code, will the assertion pass?

Answer: it depends on Point's implementation. If x is a member 
variable, then yes. If it's a getter, then doubleMyValue will 
take a rvalue and x won't be mutated and the assertion will fail.

I think this is a non-trivial conceptual problem.

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