What C GNU-isms exist?

c, gcc, language-extension

Solution

Here is a pretty comprehensive list straight from GCC's website. There seems to be quite a lot, so I wish you the best of luck sifting through it!

http://gcc.gnu.org/onlinedocs/gcc-4.2.0/gcc/C-Extensions.html

Problem

I was recently porting a project from GCC to clang(in which I fixed a number of C GNU-isms). This got me thinking: what C GNU-isms(extensions to the C language supported in GCC, which are not standardized) exist? Is there a comprehensive list anywhere?

Original source