IFTI, value types, and top-level const

[monarch_dodra]

On Sunday, 9 June 2013 at 10:49:17 UTC, Jonathan M Davis wrote:
> On Sunday, June 09, 2013 12:33:39 Peter Alexander wrote:
>> It looks like the core issue here is that it's simply not
>> possible to create a mutable copy of a const object with
>> indirection:
>
> Part of my point here (that you seem to have missed) is that 
> there is a cost
> to making it so that const is stripped from the type even if 
> you can do so. It
> _forces_ a copy if the value being passed in isn't mutable, 
> whereas if the
> constness were the same, then the value being passed in could 
> potentially be
> moved rather than copied. As such, I don't know if we even want 
> to strip the
> constness even if we can.
>
> - Jonathan M Davis

Well, these are primitives we are talking about. I'm not sure 
passing an int by value instead of by ref is much more expansive. 
We already do the same for slices/pointers, so really, all we are 
doing is making things consistent.

I agree with your point for structs though. Given any struct, 
even if POD without indirections, const means const.

But for built-in primitives, I don't think it is a problem.