`in` no longer same as `const ref`

[Q. Schroll via Digitalmars-d]

On Monday, 30 January 2017 at 12:08:06 UTC, Olivier FAURE wrote:
> 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.

Would have been a far better definition. Why does anyone really 
need a shorthand attribute for two attributes that could be 
easily spelled out? You can type anything for "const  scope" 
while programming and then do search-and-replace. That's even 
trivial.

Can't we make "in" mean "const scope ref", that binds on 
r-values, too? Effectively, that's (similar to) what "const T&" 
in C++ means. It's a non-copying const view on the object. We 
have the longstanding problem, one must overload a function to 
effectively bind both l- and r-values. That is what I'd suppose 
to be the dual to "out".