'return this' allows binding rvalues to references

[Steven Schveighoffer]

On Mon, 08 Apr 2013 13:58:17 -0400, Ali Çehreli <acehreli at yahoo.com> wrote:

> foo() below takes by-ref. Normally, rvalues cannot be passed to it:
>
> struct S
> {
>      ref S memFunc()
>      {
>          return this;
>      }
> }
>
> void foo(ref S s)
> {}
>
> void main()
> {
>      // As expected, fails to compile:
>      // foo(S());
>
>      // No problem: Just call a function that returns ref... :)
>      foo(S().memFunc());
> }

It has been brought up before.

Essentially, the compiler turns a blind eye when passing rvalues by  
reference if binding to this. It's kind of unavoidable, to prevent it  
would be a major pain point, since simple accessors should easily be able  
to be called on rvalues, and you can't remove the 'ref' of 'this'.

I recall in the past, Andrei wishes to remove that possibility (maybe I'm  
wrong), but I think it would be too impractical.

-Steve