doxygen.h is missing a \defgroup directive for libcrmcluster, and cluster.h is missing an \ingroup directive. There should be an endpoint for libcrmcluster here (update version string as needed): https://clusterlabs.org/pacemaker/doxygen/Pacemaker-2.1.7/index.html

Also, doxygen for functions in corosync.c and cpg.c should note that calls to them should be guarded by #if SUPPORT_COROSYNC.

Currently, functions whose declarations are guarded by #if SUPPORT_COROSYNC don't appear in doxygen-generated HTML at all.

Feel free to create subtasks for the SUPPORT_COROSYNC issues.