DIP77 - Fix unsafe RC pass by 'ref'

[Michel Fortin via Digitalmars-d]

On 2015-04-10 23:22:17 +0000, "deadalnix" <deadalnix at gmail.com> said:

> On Friday, 10 April 2015 at 23:18:59 UTC, Martin Nowak wrote:
>> On 04/10/2015 11:29 PM, Walter Bright wrote:
>>> 
>>> The latter.
>> 
>> Can you update that part in the DIP, it wasn't clear that the temporary
>> selectively pins RCO fields of a normal struct passed by ref.
> 
> If a struct has RCO fields, shouldn't it be an RCO itself, and as such 
> be pinned ?

Not necessarily. A @disabled postblit could make it no longer RCO 
(including a @disabled postblit in one of the fields).

> It sounds like this is implied in the DIP.

That's what I thought too. But when confronted to a case where that 
wouldn't work Walter said in this thread that the compiler would make a 
temporary of the fields. So I'm not too sure what to think anymore. The 
DIP should clarify what happens with @disabled postblit and RCO fields 
inside non-RCO structs.

-- 
Michel Fortin
michel.fortin at michelf.ca
http://michelf.ca