These are short and (hopefully) precise instructions what you need to do when you’ve built KDevelop4 from source and installed it somewhere other than your KDE libraries are (those are often from packages and then installed in /usr or /opt/kde).
I’m assuming here that you have the KDE libraries installed in /usr (i.e. from some packages) and that you’ve installed KDevelop4 into $HOME/kdevelop4 (by passing -DCMAKE_INSTALL_PREFIX=$HOME/kdevelop4 to cmake). If your paths are different just substitute them. Also I’m assuming you’re running KDevelop4 from a terminal and not via the run dialog or via a menu entry, if you want that to work you need to find out how to set environment for the whole X11 session – thats usually distro-specific.
So, first thing to do is setup the KDEDIRS magic environment variable. It tells KDE core components where to search for plugins and other data related to KDE apps and contains just a list of paths (aka prefixes) where KDE libraries and/or applications have been installed.
In my example I set KDEDIRS to point to /usr and $HOME/kdevelop4 as those are the two places where I have KDE4 apps:
Next thing is to run a KDE tool called “kbuildsycoca4”, this reads various config files that describe which plugins are available and builds a cache from that information. This is necessary so KDevelop can find all its plugins.
And last but not least you can simply run KDevelop by typing “kdevelop” and hitting Enter.