I'm currently testing HotStandby v9g.
Seems like this patch version misses to update guc.c, which still
references XLOG_DEBUG when compiled with WAL_DEBUG. This got replaced with
XLOG_DEBUG_FLUSH, *_BGFLUSH and *_REDO, resulting in a compile error. Maybe
we want to reflect those changes with new developer guc's?
-- Thanks
Bernd