#if X_VERSION < (123, 0, 0)
  alligators
  #error ""
#else
  Cape buffalos
#endif

#define v X_VERSION
#if v = (X_MAJOR, X_MINOR, X_PATCH)
  onion rings
#else
  gazpacho
  #error ""
#endif

major: X_MAJOR
minor: X_MINOR
patch: X_PATCH

#ifdef X_PRERELEASE
  prerelease: X_PRERELEASE
#else
  #error ""
#endif

#ifdef X_BUILD
  build: X_BUILD
#else
  #error ""
#endif

Coq: COQ_VERSION

OCaml pre-release:  OCAML_PRERELEASE