Nothing is logged on slot creation because ReplicationSlot->data.failover is never true. Once that's fixed by - for now - making all slots failover slots, there's a crash in XLogInsert because of the use of reserved bits in the XLogInsert info argument. Fix pushed.
I also noticed that slot drops seem are being logged whether or not the slot is a failover slot. Pushed a fix for that.
The WAL writing is now working. I've made improvements to the rmgr xlogdump support to make it clearer what's written.
Slots are still not visible on the replica so there's work to do tracing redo, promotion, slot handling after starting from a basebackup, etc. The patch is still very much WIP.
