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Re: [patch] Default to --enable-libstdcxx-time=auto
- From: Jonathan Wakely <jwakely dot gcc at gmail dot com>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: Rainer Orth <ro at cebitec dot uni-bielefeld dot de>, Benjamin Kosnik <bkoz at redhat dot com>, Paolo Carlini <paolo dot carlini at oracle dot com>, "libstdc++" <libstdc++ at gcc dot gnu dot org>, gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Fri, 24 May 2013 15:29:43 +0100
- Subject: Re: [patch] Default to --enable-libstdcxx-time=auto
- References: <20130523210611 dot GH1377 at tucnak dot redhat dot com> <ydd38tdwgis dot fsf at CeBiTec dot Uni-Bielefeld dot DE> <yddy5b5uzuq dot fsf at CeBiTec dot Uni-Bielefeld dot DE> <20130524075705 dot GK1377 at tucnak dot redhat dot com> <yddk3mopxat dot fsf at lokon dot CeBiTec dot Uni-Bielefeld dot DE> <20130524132117 dot GT1377 at tucnak dot redhat dot com> <ydd38tcpkks dot fsf at lokon dot CeBiTec dot Uni-Bielefeld dot DE> <20130524134056 dot GU1377 at tucnak dot redhat dot com> <CAH6eHdScm3PHL_HVJU7rKywvDoPwgeU_OJ1kDAS12y-v5RJbwg at mail dot gmail dot com> <20130524140748 dot GV1377 at tucnak dot redhat dot com> <20130524141622 dot GW1377 at tucnak dot redhat dot com>
On 24 May 2013 15:16, Jakub Jelinek <jakub@redhat.com> wrote:
> On Fri, May 24, 2013 at 04:07:48PM +0200, Jakub Jelinek wrote:
>> On Fri, May 24, 2013 at 02:56:24PM +0100, Jonathan Wakely wrote:
>> > > Jonathan/Benjamin, could you please review the patch in the mean time,
>> > > so that if it works well for Rainer, it can be applied immediately and
>> > > 4.8.1-rc2 rolled, even during the weekend?
>> >
>> >
>> > In the fallback for steady_clock::now() would it be easier to just
>> > call system_clock::now() instead of duplicating its logic?
>>
>> Yeah, that is what I've tried in
>> http://gcc.gnu.org/ml/gcc-patches/2013-05/msg01440.html
>> but it failed horribly, because the return type from both the static methods
>> is different (system_clock::time_point (aka chrono::time_point<system_clock,
>> duration>) in the first case,
>> steady_clock::time_point (aka chrono::time_point<steady_clock, duration>)
>> in the latter). And there is no conversion in between the two.
>>
>> Perhaps I'd have to do something like:
>> return time_point(system_clock::now().time_since_epoch());
>> ? Can try that.
>
> Ah, but the duration can be different depending on macros.
You can convert between durations: with duration_cast:
return time_point(duration_cast<duration>(system_clock::now().time_since_epoch()));