`in` no longer same as `const ref`

[Olivier FAURE via Digitalmars-d]

On Monday, 30 January 2017 at 06:38:11 UTC, Jonathan M Davis 
wrote:
> Personally, I think that effectively having an alias for two 
> attributes in a single attribute is a confusing design decision 
> anyway and think that it was a mistake, but we've had folks 
> slapping in on stuff for years with no enforcement, and 
> flipping the switch on that would likely not be pretty.
>
> - Jonathan M Davis

I've always thought of 'in' as a visual shorthand for "this 
parameter doesn't care whether you give it a deep copy or a 
shallow reference", personally.