QGIS » QGIS Application

The Debian GIS team are working to support the various ARM architectures in Debian. Earlier in the year, a pull request was merged for issue: #9917.

Unfortunately, with the newer QGIS v2.4.0 a similar problem is occurring that causes QGIS to fail to build on armel & armhf machines: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=760535.

Extract of build log (see Debian Bug for more):

/usr/include/qt4/QtCore/qglobal.h:1219:34: note: template<class T> const
T& qMax(const T&, const T&)
Q_DECL_CONSTEXPR inline const T &qMax(const T &a, const T &b) { return
(a < b) ? b : a; }
^
/usr/include/qt4/QtCore/qglobal.h:1219:34: note: template argument
deduction/substitution failed:
/«PKGBUILDDIR»/src/gui/qgscomposerview.cpp:872:189: note: deduced
conflicting types for parameter 'const T' ('float' and 'double')
newTable->setSceneRect( QRectF(
mRubberBandItem->transform().dx(), mRubberBandItem->transform().dy(),
mRubberBandItem->rect().width(), qMax( mRubberBandItem->rect().height(),
15.0 ) ) );

Peter Green investigated this and found (please read his detailed analysis in the Debian Bug):
In this case qMax is a template. The result is it will work with
arguments of any numeric type but the two arguments must be the same
type. The literal 12.0 is type double. So on a platform where qreal is
float qMax gets passed one float and one double and the compiler can't
decide which to use for the template parameter and errors out. Easy
enough to fix by casting the literal to qreal.

Unfortunately, the next problem Peter found was with the .sip file. After changing this file in a few places the build went further and then failed with:
/qgis-2.4.0/obj-arm-linux-gnueabihf/python/core/sip_corepart2.cpp:12735:67:
error: no matching function for call to 'QVector<float>::QVector(const
QVector<double>&)'
sipRaiseUnknownException();

To try and fix, Peter decided to try outright changing the type to qreal. It
looks like the API in question is totally new in 2.4 so this shouldn't
break too much third party stuff. But there were some knockon impacts within
the qgis source.

Peter's patch is attached, but because he is not sure if there are further matching changes required in the QGIS code, or whether there is a better way to fix it, we will not apply the patch in Debian without checking here first.