[Development] Best way to introduce SIC for Qt 6 (was: Branch for Qt 6)

Lars Knoll lars.knoll at qt.io
Mon Jan 21 09:15:26 CET 2019

> On 20 Jan 2019, at 06:38, Sze Howe Koh <szehowe.koh at gmail.com> wrote:
> On Tue, 15 Jan 2019 at 23:50, Thiago Macieira <thiago.macieira at intel.com> wrote:
>> On Tuesday, 15 January 2019 00:21:54 PST Lars Knoll wrote:
>>> * We regularly merge dev into it
>>> * BC breakages are fine
>>> * SC breakages require a maintainer approval and a Changelog entry marking
>>> this as a source incompatible change * All functions you’d like to remove
>>> in qt6 need to be deprecated in dev first
>> And please avoid Qt6 specific changes if you can, because of those merges.
> One of the changes we should consider is for QLabel::pixmap() and
> QLabel::picture() to return by-value instead of by-pointer. (Abandoned
> alternative at https://codereview.qt-project.org/#/c/101233/ ) This is
> source-incompatible.
> What's the best way to introduce this change?

I think the abandoned change above is a good way to do this. Introduce a new labelPixmap() method, and deprecate the one returning a QPixmap pointer. This should happen in 5.13 or 5.14. In Qt 6, we can then remove the pixmap() method returning a pointer and if we want re-introduce a simple QPixmap pixmap() const; method.


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