heads up - Qt qreal difference on ARM

[Orion Poplawski]

http://doc.qt.digia.com/4.6/qtglobal.html#qreal-typedef

typedef qreal

Typedef for double on all platforms except for those using CPUs with ARM 
architectures. On ARM-based platforms, qreal is a typedef for float for 
performance reasons.

This still seems to be the case for 4.8 as well.

This lead to the following compile error on arm in kst:

/builddir/build/BUILD/kst-2.0.7/src/libkstapp/plotrenderitem.cpp:561:33: 
error: no matching function for call to 'qMin(double&, qreal)'
    y = qMin(y, plotItem()->yMax());
                                  ^

If there is scientific type codes using qreal this might lead to some 
precision issues as well.

Is double really that much slower on arm?

-- 
Orion Poplawski
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