To install, do this:
mkdir -p build
cd build
cmake ..
make install

If you run into crashes, please rebuild with the -DCMAKE_BUILD_TYPE=debug flag passed to cmake and report a bug with the backtrace attached.

IMPORTANT: If you're using Arch Linux: Arch breaks the standard of having "python" point to a python2 implementation. This breaks stuff.
So if you're using arch, either make "python" call some python2 interpreter instead of python3 while compiling (only while compiling, doesn't matter afterwards)
or edit the file python-src/Parser/asdl_c.py and change the first line to point to your python2 implementation, so usually replace
#! /usr/bin/env python
with
#! /usr/bin/env python2

Running test suite:
To enable test building, run
  cmake .. -DKDE4_BUILD_TESTS=true
Instead of just cmake