[libcamera-devel] [PATCH v2 0/2] libcamera: revert C++17 specific code for public API

[Jean-Michel Hautbois]

On 27/01/2021 07:46, Jean-Michel Hautbois wrote:
> Hi Laurent,
> 
> On 26/01/2021 22:25, Laurent Pinchart wrote:
>> On Tue, Jan 26, 2021 at 11:19:06PM +0200, Laurent Pinchart wrote:
>>> Hi Jean-Michel,
>>>
>>> Thank you for the patch.
>>>
>>> On Tue, Jan 26, 2021 at 02:04:13PM +0100, Jean-Michel Hautbois wrote:
>>>> Some applications may not be compliant with C++17 (Chromium, as an
>>>> example). Keep the C++17 features for libcamera internals, and C++14
>>>> compliance for public API.
>>>
>>> This should be captured in the commit message of the two patches, as the
>>> cover letter won't end up in the git history.
>>>
>>> The series make sense, the more lightweight our requirements will be in
>>> terms of modern features in the public API, the more applications will
>>> be able to use libcamera. libcamera itself stays C++17, but at this
>>> point of time, sticking to C++14 in the public API isn't a huge hassle.
>>>
>>> This is of course a matter of finding a proper balance, I'm sure we will
>>> eventually want to move the public API to C++17 too. Chromium is the
>>> only application I'm aware of that is affected by the lack of C++17
>>> support, and it will eventually get migrated, solving this particular
>>> issue. We will then be able to revert the reverts, if desired.
>>>
>>> I've also been wondering if the libcamera integration in Chromium could
>>> be compiled with -std=c++17, with the rest of the browser still compiled
>>> in C++14 mode. It could be useful to get a confirmation from Google on
>>> whether this is possible or not. I've asked and am waiting for feedback,
>>> but this isn't blocking and we can move ahead with this series.
>>
>> https://github.com/jhautbois/chromium/blob/master/skia/BUILD.gn#L205
>>
>> Could something similar be done for libcamera ?
> 
> Oh, nice catch, this is why I hate BUILD.gn it is not clear where the
> options should lie to be correctly applied :-p.
> I will try and get back to you !

I can't make it work, so, if Google replies it can help, as I tried it
in several places in the BUILD.gn file and it has no effect... :-(.

>>> With the commit message updated (which can be done when applying),
>>>
>>> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>>>
>>> I'll give others a few days to shime in if desired before pushing this.
>>>
>>>> ---
>>>> Changes in v2:
>>>> - keep each revert separate
>>>>
>>>> Jean-Michel Hautbois (2):
>>>>   Revert "libcamera: span: Provide and use helper variable templates for
>>>>     type traits"
>>>>   Revert "libcamera: Use helper variable template for type traits"
>>>>
>>>>  include/libcamera/bound_method.h |  2 +-
>>>>  include/libcamera/controls.h     | 24 +++++------
>>>>  include/libcamera/object.h       |  2 +-
>>>>  include/libcamera/signal.h       |  4 +-
>>>>  include/libcamera/span.h         | 70 +++++++++++++++-----------------
>>>>  5 files changed, 48 insertions(+), 54 deletions(-)
>>
>