transporting qualifier from parameter to the return value

[Walter Bright]

Andrei Alexandrescu wrote:
> Time has come to make a decision on implementing Steven Schveighoffer's 
> proposal:

Unmentioned in the proposal is is inout a type constructor or a storage 
class? For example,

     U[inout(T)]* foo(inout(X)*** p) { ... }

This is much more complex to implement than only allowing inout at the 
top level, i.e. as a storage class.

I also prefer the idea of inout on the return type being assumed, rather 
than explicit:

     T foo(inout U p) { ... }

Yes, there's the legacy compatibility issue there. A long time ago, I 
suggested using the keyword 'return' for that, instead of inout:

     T foo(return U p) { ... }

which looks fine until you use it for member functions:

     T foo() return { ... }

ugh.