New patch series attached. I plan to commit 0001 and 0002 soon, unless
there are objections.
0001 causes the "C" and "POSIX" locales to be treated with
memcmp/pg_ascii semantics in ICU, just like in libc. We also considered
a new "none" provider, but it's more invasive, and we can always
reconsider that in the v17 cycle.
0002 introduces an upgrade check for users who have explicitly
requested provider=icu and iculocale=C on older versions, and rejects
upgrading from v15 in that case to avoid index corruption. Having such
a collation is almost certainly a mistake by the user, because the
collator would not give the expected memcmp semantics.
--
Jeff Davis
PostgreSQL Contributor Team - AWS