may crash before splash screen on 2.1, 2.2, or master with Qt 5.10 due to diverged copy-and-pasted QPaintEnginePrivate header file
Was experiencing a strange segfault when use Qt 5.10. I don't know if it specifically affects armv7 but that is the only machine I am on now...the problem started I believe when arch linux moved to Qt 5.10, but it affects both the arch linux official 2.1 build, as well as when I self build 2.1 or 2.2 or master. No problem when I use an older Qt. After a long investigation (https://musescore.org/en/node/268374) I finally discovered that the problem resulted from that the fact that mscore/svngenerator.cpp's SvgPaintEnginePrivate class has been extending QPaintEnginePrivate, but the file qpaintengine_p.h was copy-and-pasted from over 6 years ago. In that file you will notice a warning from Qt:
// W A R N I N G
// This file is not part of the Qt API. It exists for the convenience
// of other Qt classes. This header file may change from version to
// version without notice, or even be removed.
// We mean it.
So they did mean it, and turns out after much investigation (building Qt 5.10 debug version from source and stepping through the constructor and deconstructor) I noticed some very odd things happening around this QPaintEnginePrivate class...basically it's binary memory contents were not adhering to what the C++ code says should be happening to it. I then noticed that this private Qt header qpaintengine_p.h has indeeded diverged from it's original state 6+ years ago.