The last few days I played a bit with tinycc an extremely small and fast C compiler.
I submitted a patch which enables tcc to handle the restrict keyword within an array context. This allowed me to build dwm with tcc. While trying to compile st I found a bug in the preprocessor, so I submitted another patch.
Unfortunately my C knowledge is rather limited and the tinycc source is not that easy to understand (at least for me) otherwise I could fix more serious bugs.
Anyway, I will continue to play around with it and throw random code at it.