reg* checks in pg_upgrade are out of date

Hi,

It seems the list of reg* types and the check for them in pg_upgrade
have gone out of sync. We have the following reg* types:

SELECT typname FROM pg_type WHERE typname LIKE 'reg%' order by typname;
┌───────────────┐
│ typname │
├───────────────┤
│ regclass │
│ regconfig │
│ regdictionary │
│ regnamespace │
│ regoper │
│ regoperator │
│ regproc │
│ regprocedure │
│ regrole │
│ regtype │
└───────────────┘
(10 rows)

but pg_upgrade doesn't consider all of them:

/*
* While several relkinds don't store any data, e.g. views, they can
* be used to define data types of other columns, so we check all
* relkinds.
*/
res = executeQueryOrDie(conn,
"SELECT n.nspname, c.relname, a.attname "
"FROM pg_catalog.pg_class c, "
" pg_catalog.pg_namespace n, "
" pg_catalog.pg_attribute a "
"WHERE c.oid = a.attrelid AND "
" NOT a.attisdropped AND "
" a.atttypid IN ( "
" 'pg_catalog.regproc'::pg_catalog.regtype, "
" 'pg_catalog.regprocedure'::pg_catalog.regtype, "
" 'pg_catalog.regoper'::pg_catalog.regtype, "
" 'pg_catalog.regoperator'::pg_catalog.regtype, "
/* regclass.oid is preserved, so 'regclass' is OK */
/* regtype.oid is preserved, so 'regtype' is OK */
" 'pg_catalog.regconfig'::pg_catalog.regtype, "
" 'pg_catalog.regdictionary'::pg_catalog.regtype) AND "
" c.relnamespace = n.oid AND "
" n.nspname NOT IN ('pg_catalog', 'information_schema')");

(I don't get the order here btw)

ISTM when regrole and regnamespace were added, pg_upgrade wasn't
considered. It turns out that regrole is safe, because we preserve user
oids, but regnamespace isn't afaict. I don't think it's extremely
likely that users store such reg* columns in tables, but we probably
still should fix this.

Greetings,

Andres Freund