http://wiki.dlang.org/DIP25

[Dicebot via Digitalmars-d]

On Monday, 29 December 2014 at 04:13:18 UTC, Andrei Alexandrescu 
wrote:
> Walter's reasoning was: we have inout for propagating 
> qualifiers from a parameter ("this" is also a parameter) to the 
> output, so we can use it for propagating aliasing information 
> as well.

Yay! I have been asking for it since scope threads started :)

I like the intention behind the DIP and I think idea itself is 
sound and fits naturally into existing language.

But this example confuses me:

@safe ref int wrongIdentity(ref int x) {
     return x; // ERROR! Cannot return a ref, please use "ref 
inout"
}

@safe ref int identity(ref inout int x) {
     return x; // fine
}

If existing meaning of is to be kept too second example should 
look like this:

@safe ref inout int identity(ref inout int x) {
     return x; // fine
}

otherwise it allows silent casting of const reference to mutable 
one!