To C++11 or not?

[Albert Astals Cid]

El divendres, 30 de desembre de 2016, a les 15:32:24 CET, Martin Gräßlin va 
escriure:
> Am 2016-12-30 15:25, schrieb David Faure:
> > On vendredi 30 décembre 2016 12:56:09 CET Albert Astals Cid wrote:
> >> El divendres, 30 de desembre de 2016, a les 12:24:38 CET, Luigi
> >> Toscano va
> >> 
> >> escriure:
> >> > Il 30 dicembre 2016 10:30:22 CET, Kevin Funk <kfunk at kde.org> ha 
scritto:
> >> > >Following-up on this thread, since I saw some more discussion about
> >> > >C++11
> >> > >
> >> > >usage in this RR:
> >> > >  https://git.reviewboard.kde.org/r/129724/
> >> > >
> >> > >Let's put this into some concrete actions, finally. I think we all
> >> > >agree
> >> > >nullptr & override are probably the most apparent issues (since
> >> > >compilers
> >> > >started to warn about both), and *having* 'override' is actually super
> >> > >useful
> >> > >for preventing programmer faults.
> >> > >
> >> > >Let's just speak about allowing nullptr & override, allowing the full
> >> > >set of C
> >> > >++11 is *not* feasible. Reason: Lot's of C++11 feature are only
> >> > >available only
> >> > >in MSVC2015, so we'd just be able to support the latest VS. See [2].
> >> > >
> >> > >Looking at [1] I still see we list GCC 4.5 as minimum requirement.
> >> > >That's
> >> > >pretty ancient. 4.5.1 got released Jul 2010 [3]
> >> > >
> >> > >If we raise that to GCC 4.6 (4.6.0 being released Mar 2011), we can
> >> > >use
> >> > >
> >> > >'nullptr' unconditionally. ktexteditor already did that in public
> >> > >headers for
> >> > >quite some time -- no-one complained.
> >> > >
> >> > >If we raise that to GCC 4.7 (4.7.0 being released Mar 2012), we can
> >> > >use
> >> > >
> >> > >'override' unconditionally *.
> >> > >
> >> > >We already use MSVC2012 as min VS dep, this version has full nullptr &
> >> > >override support. I don't see anyone using MSVC2010 for compiling KF5
> >> > >to be
> >> > >honest...
> >> > >
> >> > >Proposal for [1]:
> >> > >- Raise min GCC version to 4.7
> >> > >- Allow to use override unconditionally
> >> > >- Allow to use nullptr unconditonally
> >> > >
> >> > >ACK?
> >> > >
> >> > >
> >> > >PS: I can do the work, I can script the refactoring with clang-tidy.
> >> > >
> >> > >Let's move forward please.
> >> > 
> >> > Hi, this is a really good analysis (also for future reference). In
> >> > order
> >> > to
> >> > complete it, given that the original idea was "follow Qt's
> >> > requirement",
> >> > and that we increased in time the required version of Qt, what is the
> >> > current status regarding compilers and Qt?
> >> 
> >> Our min requirement is Qt 5.5 which according to
> >> http://doc.qt.io/qt-5/supported-platforms-and-configurations.html
> >> compiles with GCC 4.6 (Qt 5.6 has the same supported GCC it seems)
> > 
> > Then that's a no-brainer, we can require gcc 4.6 too.
> > 
> > Qt 5.9 (currently "git dev branch") uses override rather than
> > Q_DECL_OVERRIDE,
> > but we're far from requiring 5.9.
> > 
> > This leads to a different proposal:
> > - Raise min GCC version to 4.6
> > - Allow to use nullptr unconditionally
> > - Use Q_DECL_OVERRIDE.
> > 
> > I fully agree that "having 'override' is actually super useful for
> > preventing
> > programmer faults", but that also works if it's spelled out
> > Q_DECL_OVERRIDE
> > and only ineffective for people *using* frameworks on an older system
> > with gcc
> > 4.6. It's still effective for all of us who are working on frameworks,
> > which
> > is where the benefit of "override" is.
> 
> What's the plan to enforce that? How is build.kde.org checking that we
> don't use override instead of Q_DECL_OVERRIDE?

I guess you can stop worrying. Stephen Kelly just reverted that change that 
had been approved in a review request without any discussion.

Very sad,
  Albert


> 
> This is the point I disagree with. We define nice rules and have no
> means at all to ensure that they are enforced. That's something I have
> brought to the attention of this mailing list several times over the
> last years. Unfortunately nothing has changed.
> 
> In my opinion we are lying to ourself and to everybody who wants to use
> frameworks if we say "can be compiled with gcc 4.6" when we aren't even
> testing that.
> 
> So please let's get the ordering right: ensure that it compiles with gcc
> 4.6, then say we support that. The only other option is to say we
> require whatever gcc version build.kde.org is using.
> 
> Cheers
> Martin