Official C Challenge ①

Task:  Come up with an extension to the C programming language.  Provide a clear description of the extension, and a code sample that clearly shows what the extension is intended to do.

Prize:  (Winning criteria are not specified.)  The winner will have his extension featured in the C11 language standard.

My entry:  ... Sorry, I think C is perfect in every way already.

>>1
How about a new _Alias keyword, so you can do type-punning in a portable way? Union type-punning is limited and still technically a violation of the spec...