macros - How can I generate unique values in the C preprocessor?

Question

I'm writing a bunch of related preprocessor macros, one of which generates labels which the other one jumps to. I use them in this fashion:

MAKE_FUNNY_JUMPING_LOOP(
  MAKE_LABEL();
  MAKE_LABEL();
)

I need some way to generate unique labels, one for each inner MAKE_LABEL call, with the preprocessor. I've tried using __LINE__, but since I call MAKE_LABEL inside another macro, they all have the same line and the labels collide.

What I'd like this to expand to is something like:

MAKE_FUNNY_JUMPING_LOOP(
  my_cool_label_1:  // from first inner macro
  ...
  my_cool_label_2:  // from second inner macro
  ...
)

Is there a way to generate hashes or auto-incrementing integers with the preprocessor?

Answer 1

If you're using GCC or MSVC, there is __COUNTER__.

Other than that, you could do something vomit-worthy, like:

#ifndef USED_1
#define USED_1
1
#else
#ifndef USED_2
#define USED_2
2
/* many many more */
#endif
#endif