transporting qualifier from parameter to the return value

[Andrei Alexandrescu]

Time has come to make a decision on implementing Steven Schveighoffer's 
proposal:

http://www.prowiki.org/wiki4d/wiki.cgi?LanguageDevel/DIPs/DIP2

It's been in the back of my mind for a while now, I don't find a fault 
with it, it solves a very unpleasant problem that would seriously mar 
qualifiers, and although it doesn't solve 100% of the potential cases, 
it does solve a good fraction of them. I am confident that we can 
require body duplication for the remaining stragglers with a straight face.

My main concern is allowing shared to participate to the inout 
transportation. I am tempted to allow it, but shared is constrained much 
more severely than the other two.

To avoid problems with the existing uses of inout (which is an old 
synonym for ref), the language requires that you redundantly use inout 
in the return type as well. We could eliminate that in D3.

Any thoughts would be appreciated.


Andrei