About how to install the development environment for Qt 5.x.x on Raspberry Pi 2

It takes a long time

You can download the source code and compile it yourself. It takes about 50 hours on a Raspberry Pi 2. Particularly long will it take if you choose to compile to static build. It's a good idea, Slackware is running the Qt 4 librarie, so programs you compile will not work with Slackwares dynamic libraries. You must have a 32 Gb MicroSD card when you compile the source code. 16 GB is not enough.

You can find a pre-compiled static Qt 5.5.0 for Slackware on Raspberry Pi 2 here (147 MB, uncompressed 424 MB )

I have used these compilation settings:
./configure -prefix /opt/Qt/qt5.5.0_static -developer-build -release -opensource -static -qt-xcb -confirm-license -nomake examples -nomake tests -qt-zlib -qt-libpng -qt-libjpeg -optimized-qmake

mkdir /opt/Qt
Unzip to /opt/Qt. NOTE! Do not change any names or paths. It will not work.

Updated 2015-08-02

Make sure that this is in the * .pro file:
Now just move your projects to Rp 2 and run
make release

We welcome feedback and bug reports
I gratefully accept any comments!