[boost] Re: Perfect moving (almost)

From: David Abrahams (dave_at_[hidden])
Date: 2004-02-11 13:20:36

"Peter Dimov" <pdimov_at_[hidden]> writes:

> David Abrahams wrote:
>> "Peter Dimov" <pdimov_at_[hidden]> writes:
>>
>>> David Abrahams wrote:
>>>> "Peter Dimov" <pdimov_at_[hidden]> writes:
>>>>
>>>>> The compiler is allowed to elide a temporary created by a copy
>>>>> constructor.
>>>>>
>>>>> The compiler is _not_ allowed to elide a temporary created by some
>>>>> other constructor, because this changes observable behavior and is
>>>>> not explicitly allowed.
>>>>
>>>> I think what's explicitly allowed depends on your reading of 8.5.3/5
>>>
>>> No, the relevant portion here is 12.8/15.
>>
>> 1. Do you realize that 12.8/15 was almost completely rewritten by
>>    Core issue 20?
>
> No, I did not, thanks for the pointer. No relevant changes, though. Only
> copy constructors can be optimized out.
>
>> 2. I still think it's arguable that 8.5.3/5 does not require a copy
>>    constructor to be used in my example, making 12.8/15 irrelevant
>>    AFAICT.
>
> Well, I suppose that you could argue that if you like, but does it
> help your cause? ;-)

I think so, and IIUC Rani might be making the same point.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com