FOR PORTION OF bugs

Hi Hackers,

Noah Misch found a number of new FOR PORTION OF bugs with some LLM
investigation. I've attached the original prompt and findings. Here is
a list with my own description of each:

D1: A DO INSTEAD rule skips inserting leftovers. (Already reported by [0].)
D2: PREPARE requires casting parameters in FOR PORTION OF bounds (e.g.
$1::date), but we should coerce these automatically.
D3: EXPLAIN (GENERIC_PLAN) fails with `no value found for parameter 1`
D4: EXPLAIN with `FOR PORTION OF (null)` raises an error about the null target.
D5: elog if the range column's default opclass is for a concrete range
type, not anyrange.
D6: Under plain inheritance, statement-level insert triggers for
temporal leftovers fire against the parent table, not the child.
D7: Error hint is misleading if a temporal leftover's BEFORE trigger
modifies a row that is later changed by the top-level statement.
D8: A temporal leftover is not inserted if its BEFORE INSERT trigger
returns null. (Already reported by [1].)
D9: FOR PORTION OF bound expressions are evaluated more than once. A
function declared STABLE but not actually STABLE would get
inconsistent results. Also reachable with current_setting() +
set_config().
D10: EXPLAIN evaluates functions in the FOR PORTION OF bounds.
D11: A WITH CHECK OPTION failure blames the temporal leftover when it
should blame the original update.
D12: pg_get_ruledef deparses a null bound as NULL::unknown not NULL::date.
D13: Docs should clarify that you need permission on the range column.
D14: Error message is misleading for a view referencing the range column twice.

I've got some patches to fix all these (with D2+D12 grouped and
D3+D4+D10 grouped), but I'll make a separate thread for each fix. I
just wanted to have this message as something I could reference from
there.

[0] https://www.postgresql.org/message-id/flat/CAON2xHO5FJ1jC87cQhGg%2BKMG5QR7ZaifJwN24rPjMqCGYn-hzA%40mail.gmail.com
[1] https://www.postgresql.org/message-id/flat/CAN4CZFNSOA_LXWKC6sAOduWVsaxjzmFBNEHUQii89KUnMhBtcw%40mail.gmail.com

Yours,

--
Paul ~{:-)
pj(at)illuminatedcomputing(dot)com