[Development] Proposal: Deprecating platforms in Qt 5.6 that don't support lambda

[Rafael Roquetto]

On Fri, Feb 20, 2015 at 03:01:01PM +0100, Olivier Goffart wrote:
> On Friday 20 February 2015 11:52:32 Rafael Roquetto wrote:
> > On Fri, Feb 20, 2015 at 02:37:09PM +0100, Olivier Goffart wrote:
> > > On Friday 20 February 2015 11:17:51 Rafael Roquetto wrote:
> > > > On Fri, Feb 20, 2015 at 12:32:45PM +0100, Olivier Goffart wrote:
> > > > > On Friday 20 February 2015 11:15:32 BogDan wrote:
> > > > > > I fully agree with you, but, sadly, I think it will not be possible
> > > > > > in
> > > > > > 5.x.
> > > > > 
> > > > > We started supporting C++98 during the course of Qt 4.x.
> > > > > We dropped MSVC 6, in Qt 4.5 (despite there was still people using it)
> > > > > and
> > > > > were able to finally use member template functions for example and
> > > > > deprecate qObjectFind and such.
> > > > 
> > > > This works when there are alternatives. In the case of QNX, *if* this
> > > > has
> > > > the side effect of Qt not being able to be built against 6.6.0 (perhaps
> > > > they will have a newer compiler until then, but I can't assume that),
> > > > then
> > > > you need to deprecate the entire platform.
> > > 
> > > Yes. The same way we deprecated Mac OSX 10.6 during Qt 5.x lifetime,  or
> > > Windows 9x during Qt 4.x lifetime.
> > > 
> > > My point is that there is no reason to say that this won't happen in Qt
> > > 5.x
> > > lifetime.
> > 
> > Which is not ok.
> > 
> > I got your point. But while it is reasonable to push users from
> > Windows 9x or OS X 10.6, in the case of QNX, you will be pushing users
> > away from Qt. In the case of QNX 6.5.0, one could even argue that they
> > could update to 6.6.0 - something that is still not trivial at all. But you
> > drop 6.6.0, you basically remove Qt from a giant slice of automotive,
> > industrial and aerospacial markets. Let's bear this in mind before deciding
> > to pull the plug.
> 
> I did not say we need to drop support TODAY. Qt 5.x is there for many more 
> years.
> 
> Now, back to the topic, it is true that if we want to start using C++11 in Qt 
> we would need to find a solution for QNX. Is there really no way to use a more 
> recent gcc or clang to target QNX 6.6 or 6.5?

The only way afaik is if they release a service pack with an updated
compiler. The QNX toolchain is shipped in the form of what they call an SDP
(Software Development Kit), which ships everything from target libraries, host
tools, and an IDE called Momentics. It is not really modular to the point we
could independently switch compilers.

Now, having said that, QNX 6.6.0 is gcc 4.7 based. Compiler-wise, that should
be enough for lambdas, but correct me if I am wrong.
The problem with 6.6.0 starts to arise when we
decide to use features that their libcpp does not support.

QNX 6.5.0 OTOH is gcc 4.4.2 based, and its libcpp does not support C++11.

What kind of changes, apart from lambdas, are we willing to push in practice?
I will investigate what can be done in practice to try to work around this
from the QNX side.

Thanks,
Rafael


> 
> -- 
> Olivier 
> 
> Woboq - Qt services and support - http://woboq.com - http://code.woboq.org

-- 
Rafael Roquetto | rafael.roquetto at kdab.com | Software Engineer
Klarälvdalens Datakonsult AB, a KDAB Group company
Tel. Sweden (HQ) +46-563-540090, USA +1-866-777-KDAB(5322)
KDAB - Qt Experts - Platform-independent software solutions
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/x-pkcs7-signature
Size: 4861 bytes
Desc: not available
URL: <http://lists.qt-project.org/pipermail/development/attachments/20150220/eb521589/attachment.bin>