[dietrichepp]

It's a GCC extension. https://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html

[techdragon]

Is there an equivalent for Clang/LLVM?

[cjcole]

Yes.

http://blog.llvm.org/2010/01/address-of-label-and-indirect-b...

A venerable interpreter implementation trick.