test failure with gcc-12 -O3 -march=native

Hi,

For my optimized builds I've long used -O3 -march=native. After one of the
recent package updates (I'm not certain when exactly yet), the main regression
tests started to fail for me with that. Oddly enough in opr_sanity:

-- Ask access methods to validate opclasses
-- (this replaces a lot of SQL-level checks that used to be done in this file)
SELECT oid, opcname FROM pg_opclass WHERE NOT amvalidate(oid);
- oid | opcname
------+---------
-(0 rows)
+INFO: operator family "array_ops" of access method hash contains function hash_array_extended(anyarray,bigint) with wrong signature for support number 2
+INFO: operator family "bpchar_ops" of access method hash contains function hashbpcharextended(character,bigint) with wrong signature for support number 2
...
+ 16492 | part_test_int4_ops
+ 16497 | part_test_text_ops
+(43 rows)

Given that I did not encounter this problem with gcc-12 before, and that
gcc-12 has been released, it seems less likely to be a bug in our code
highlighted by a new optimization and more likely to be a bug in a gcc bugfix,
but it's definitely not clear.

I only investigated this a tiny bit so far. What fails is the
procform->prorettype != restype comparison in check_hash_func_signature().

Greetings,

Andres Freund