What's the correct opEquals signature for structs?

[Jonathan M Davis]

On Wednesday, March 14, 2012 01:36:40 Alex Rønne Petersen wrote:
> On 14-03-2012 01:18, Jonathan M Davis wrote:
> > On Wednesday, March 14, 2012 01:14:04 Alex Rønne Petersen wrote:
> >> On 14-03-2012 01:10, Jonathan M Davis wrote:
> >>> On Tuesday, March 13, 2012 22:03:45 Alex Rønne Petersen wrote:
> >>>> Did you see my other post? Maybe we could do something like this:
> >>>> 
> >>>> equals_t opEquals()(const auto ref SysTime rhs) const pure nothrow
> >>> 
> >>> That would probably work (though I wouldn't use equals_t, since it seems
> >>> like an utterly pointless alias to me). Still, it shouldn't have to be
> >>> templated to work with auto ref.
> >>> 
> >>> - Jonathan M Davis
> >> 
> >> That's arguable...
> >> 
> >> The thing is, auto ref, when used on class methods cannot work. The
> >> reason is simple: Inheritance. An overriding method can't magically take
> >> both a value and a reference.
> >> 
> >> Obviously we can special-case auto ref on structs, but... is this really
> >> desirable?
> > 
> > As I understand it, auto ref is supposed to work with _any_ function. The
> > _compiler_ decides whether it's best to use a ref or a value. That may
> > mean
> > that you actually get two of the same function. I don't know. I do know
> > that Walter misunderstood what Andrei meant and made it a template thing
> > when it wasn't supposed to be. Supposedly, he's going to fix it, but he
> > hasn't yet.
> > 
> > - Jonathan M Davis
> 
> How would it ever work? One entry in a vtable can't point to two functions.

I don't know. I believe that Timon had an explanation for how auto ref is 
supposed to work that he posted in a discussion semi-recently, but I don't 
remember the details. Regardless, as I understand it, it _is_ possible to have 
a non-templated function which can take an argument by either ref or value at 
the compiler's discretion and that that's what auto ref is supposed to do. But 
I don't know the details.

- Jonathan M Davis