Passing structs to functions

[phant0m via Digitalmars-d-learn]

On Saturday, 2 July 2016 at 18:43:51 UTC, ketmar wrote:
> void boo() (in auto ref MyStruct s) { ... }
>
> this will accept both lvalues and rvalues, and will avoid 
> copying if it can.

Thank you! Could you please explain what does "auto" in this 
context mean?