I've been working on some "extensions" to C using tcc as a base. The website is
http://www.tinycx.org. I think there are other project that take tcc and experiment on it. In terms of SEH what I've done with tinycx is added some simple error handling with the reserved labels error: and finally:. The implementation uses setjmp/longjmp but that's because it was easier for me. Other features to C I've added are module support, multiple return values, function overloading, polymorphism, type inference. If you check it out any feedback you have would be appreciated.