Here is a list of all documented macros with links to the documentation:

XAPIAN_AT_LEAST : version.h
XAPIAN_DOCID_BASE_TYPE : version.h
XAPIAN_ENABLE_VISIBILITY : version.h
XAPIAN_HAS_GLASS_BACKEND : version.h
XAPIAN_HAS_HONEY_BACKEND : version.h
XAPIAN_HAS_INMEMORY_BACKEND : version.h
XAPIAN_HAS_REMOTE_BACKEND : version.h
XAPIAN_MAJOR_VERSION : version.h
XAPIAN_MINOR_VERSION : version.h
XAPIAN_REVISION : version.h
XAPIAN_REVISION_TYPE : version.h
XAPIAN_TERMCOUNT_BASE_TYPE : version.h
XAPIAN_TERMPOS_BASE_TYPE : version.h
XAPIAN_TOTALLENGTH_TYPE : version.h
XAPIAN_VERSION : version.h