#define guard(_name) \
          CLASS(_name, __UNIQUE_ID(guard))

  #define CLASS(_name, var)                                               \
          class_##_name##_t var __cleanup(class_##_name##_destructor) =   \
                  class_##_name##_constructor

  #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)

Yeah Rust wins this one hands down, without breaking a sweat, and without really even noticing there was a competition.