I've heard of a lot of cool GCC extensions and built-in functions over the years, but I always wind up forgetting about them before thinking of using them.
What are some cool GCC extensions and built-ins, and some real-life examples of how to put them to use?
GCC provides many features as compiler extensions, off the top of mind and frequently used by me are:
Statement Expressions
Designated Initializers
There are many more documented on the GCC website here.
Caveat: However, using any form of compiler extensions renders your code non-portable across other compilers so do use them at that risk.