I reviewed v6 too. The parser, rewriter, planner and executor changes look correct to me. I also checked mixed conflict/non-conflict rows, correlated subqueries, view-expression rewriting and column-level privileges.
I agree that allowing unqualified column names in ON CONFLICT SET and WHERE should be a separate change. This patch does not depend on it. There are two small typos: "espectively" in setrefs.c, and Viktor's previously reported "EXLCUDED" in returning.sql and returning.out. Neither needs another patch revision. I think this[0] is ready for committer. I'll flip the status. Best regards, Andrey Borodin. [0] https://commitfest.postgresql.org/patch/5854/
