t / t4018 / cpp-skip-labelson commit git-compat-util.h: don't define _XOPEN_SOURCE on cygwin (3a0a3a8)
   1void RIGHT (void)
   2{
   3repeat:         // C++ comment
   4next:           /* C comment */
   5        do_something();
   6
   7        ChangeMe;
   8}