I just submitted https://issues.dlang.org/show_bug.cgi?id=15328 which is currently blocking my work on containers.

In brief the postblit isn't called upon calling

Range save() { return this; }

which of course is less than helpful.

Reductions of the example would be awesome - I reduced it a fair amount compared to the initial code, but I'm sure someone without that context could do a much better job.


Thanks,

Andrei

On Friday, 13 November 2015 at 17:01:34 UTC, Andrei Alexandrescu wrote:
> I just submitted https://issues.dlang.org/show_bug.cgi?id=15328 which is currently blocking my work on containers.
>
> In brief the postblit isn't called upon calling
>
> Range save() { return this; }
>
> which of course is less than helpful.
>
> Reductions of the example would be awesome - I reduced it a fair amount compared to the initial code, but I'm sure someone without that context could do a much better job.
>
>
> Thanks,
>
> Andrei

afaik that's RVO, isn't it?
D's RVO semantics are pretty much unspecified still(outside of dmd,) I believe(don't quote me) that walter said it's supposed to be part of the spec but I could never find anything.

there's a few bugs filed on it
https://issues.dlang.org/show_bug.cgi?id=10372
https://issues.dlang.org/show_bug.cgi?id=11287
https://issues.dlang.org/show_bug.cgi?id=10371

probably others

On Friday, 13 November 2015 at 17:25:44 UTC, rsw0x wrote:
> afaik that's RVO, isn't it?
> D's RVO semantics are pretty much unspecified still(outside of dmd,) I believe(don't quote me) that walter said it's supposed to be part of the spec but I could never find anything.

Well, RVO is used when the value being returned is a local variable. The compiler knows that it can be moved rather than copied, so it's moved. However, the this pointer/reference isn't a local variable. It's a member variable. So, it can't be moved. So, RVO shouldn't kick in when returning this.

- Jonathan M Davis

On 11/13/2015 12:25 PM, rsw0x wrote:
> On Friday, 13 November 2015 at 17:01:34 UTC, Andrei Alexandrescu wrote:
>> I just submitted https://issues.dlang.org/show_bug.cgi?id=15328 which
>> is currently blocking my work on containers.
>>
>> In brief the postblit isn't called upon calling
>>
>> Range save() { return this; }
>>
>> which of course is less than helpful.
>>
>> Reductions of the example would be awesome - I reduced it a fair
>> amount compared to the initial code, but I'm sure someone without that
>> context could do a much better job.
>>
>>
>> Thanks,
>>
>> Andrei
>
> afaik that's RVO, isn't it?

The repro has a bug itself, I'll get back with one that's actually supposed to pass. -- Andrei