[QGIS-Developer] how compatible .qml files are ?

[Nyall Dawson]

On Mon, 2 Sep 2019 at 20:30, Sandro Santilli <strk at kbt.io> wrote:
>
> On Sun, Sep 01, 2019 at 08:19:18AM +1000, Nyall Dawson wrote:
> > On Sat, 31 Aug 2019 at 17:02, Sandro Santilli <strk at kbt.io> wrote:
>
> > > Do you know which commit dropped the backward compatibility, exactly ?
> > > Note that "something completely unused" (just re-reading your quoted
> > > text) was actually still used by QGIS itself...
> >
> > No, no idea sorry. It would have been 2-3 years ago now, and it was a
> > mass deletion commit, so git blame won't be much use. You may be able
> > to git blame qgsvectorlayer.cpp or qgsvectorlayerrenderer.cpp to find.
>
> Could this be the one?
>
>   commit 8e5fb436b702b9ab3d2112557f57e5a49cdea03a
>   Author: Martin Dobias <wonder.sk at gmail.com>
>   Date:   Wed Dec 14 09:45:39 2016 +0800
>
>       Remove QgsLabelingEngineInterface base class and implementation in QgsPalLabeling
>
>       It was ready to go for some time, just waiting for QgsMapRender that still used it.
>
>    src/core/qgsvectorlayerrenderer.cpp | 122
>   +++++++++++++++++++++++++++++++++----------------------------------------------------------------------
>    1 file changed, 39 insertions(+), 83 deletions(-)
>
> Unfortunately `git log --grep compat` doesn't give many hints,
> and the NEWS file doesn't have any section of broken backward
> compatibility for the 3.0 section either.

https://github.com/qgis/QGIS/commit/034147886448b49659ec658ddba08a7aa5794b7c

Just be aware that if you're thinking of restoring this code in master
-- it's extremely unlikely to be accepted. You'd need to instead port
it to a python plugin and take on the related maintenance burden
yourself.

Nyall