auto ref function parameters in a free function

[Vlad Levenfeld via Digitalmars-d-learn]

On Sunday, 3 August 2014 at 20:10:39 UTC, Martijn Pot wrote:
> What is the benefit of 'auto ref' over 'in' as you are changing 
> a nor b?

Because

   less_than (T)(T a, T b)

(or in, or const T) will copy a and b on their way into the 
function. Usually this is ok but certain data structures I use 
are not intended to be copied, or they are just very large or 
have very elaborate constructors that take up time and resources, 
or something.

I don't know if inlining would solve this or not but as far as I 
know there is no way to rely on inlining currently.