[Development] Remove OSX 10.6 Build?

[Jake Petroules]

On 2014-03-24, at 06:16 PM, Kuba Ober <kuba at mareimbrium.org> wrote:

> On Jan 21, 2014, at 5:23 AM, Sorvig Morten <Morten.Sorvig at digia.com> wrote:
> 
>> I agree with many of these arguments, and I was in favor of setting the minimum supported version to 10.7 back when we started Qt 5 development. But we did make the decision to support 10.6. The implementation effort has been made and that decision should be respected.
>> 
>> Obviously it’s not going to stand forever, especially when seeing the strong opinions from the Qt on Mac developers. We are moving in the direction of not supporting 10.6. The 5.3 binary packages will not support it. QtWebkit lives its own life - if upstream does not support 10.6 then there is little we can do.
>> 
>> When we drop support for 10.6 we are going to remove the 10.6 code and start using ARC. I don’t think there’s much room for "community support" for 10.6 - if we have to keep the manual reference counting code paths we might as well fully support it.
> 
> Per Apple [1]:
> 
> "ARC is supported in Xcode 4.2 for OS X v10.6 and v10.7 (64-bit applications) and for iOS 4 and iOS 5.
> Weak references are not supported in OS X v10.6 and iOS 4.”
> 
> Presumably ARC could be used without dropping 10.6 support, then?
> 
> For what it’s worth, I’ve updated to Mavericks a couple days after release, but straight from 10.6! I’ve evaluated 10.8 in the meantime, but wasn’t running it most of the time. So I’ve been a 10.6 user on 3 machines up till Oct 2013.
> 
> Cheers, Kuba Ober
> 
> [1]: https://developer.apple.com/library/mac/releasenotes/ObjectiveC/RN-TransitioningToARC/Introduction/Introduction.html
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Just to restate: yes, that is correct ARC can be used without dropping 10.6 support. It's also possible to enable zeroing weak references on 10.6 by means of these compatibility stubs: https://github.com/plausiblelabs/PLWeakCompatibility I'm not sure if that's stable enough to be used within Qt directly but as stated in the readme, all the tricky business happens on OSes (i.e. Snow Leopard) which will not receive further updates.

Pretty much the only thing you lose with ARC is that it's 64-bit only and thus using it means waving goodbye to 32-bit Qt on OS X completely. I don't know if this is a problem for anyone. There's also a selection of classes to which zeroing weak references cannot be made at all, and this list has changed from release to release.

ARC may not actually benefit Qt all that much; our use of it is primarily limited to the Cocoa platform plugin, and it can't help with any CoreFoundation memory management, which we probably use more of than Cocoa anyways.
-- 
Jake Petroules
Chief Technology Officer
Petroules Corporation · www.petroules.com
Email: jake.petroules at petroules.com

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