How to Choose the Right Compiler for Your Needs

I assume I can throw pretty much any C++ ish code into C line so like I use GCC at work and I'm going to use every extension we can possibly find. It makes me wonder how on earth you deal with the fact that you're using clang D which doesn't necessarily support everything that GCC does. There may be other vendor extensions out there that other people might be using in their compiler and they can't use C line if you can't understand their code. How do you decide what goes into your sort of superset of all C ++ features?