Fix omissions in support for the "regcollation" type.

The patch that added regcollation doesn't seem to have been too
thorough about supporting it everywhere that other reg* types
are supported.  Fix that.  (The find_expr_references omission
is moderately serious, since it could result in missing expression
dependencies.  The others are less exciting.)

Noted while fixing bug #17483.  Back-patch to v13 where
regcollation was added.

Discussion: https://postgr.es/m/1423433.1652722406@sss.pgh.pa.us

src/backend/catalog/dependency.c

@@ -1842,6 +1842,13 @@ find_expr_references_walker(Node *node,
 						add_object_address(OCLASS_TYPE, objoid, 0,
 										   context->addrs);
 					break;
+				case REGCOLLATIONOID:
+					objoid = DatumGetObjectId(con->constvalue);
+					if (SearchSysCacheExists1(COLLOID,
+											  ObjectIdGetDatum(objoid)))
+						add_object_address(OCLASS_COLLATION, objoid, 0,
+										   context->addrs);
+					break;
 				case REGCONFIGOID:
 					objoid = DatumGetObjectId(con->constvalue);
 					if (SearchSysCacheExists1(TSCONFIGOID,

src/backend/utils/adt/selfuncs.c

@@ -4305,6 +4305,7 @@ convert_to_scalar(Datum value, Oid valuetypid, Oid collid, double *scaledvalue,
 		case REGOPERATOROID:
 		case REGCLASSOID:
 		case REGTYPEOID:
+		case REGCOLLATIONOID:
 		case REGCONFIGOID:
 		case REGDICTIONARYOID:
 		case REGROLEOID:
@@ -4436,6 +4437,7 @@ convert_numeric_to_scalar(Datum value, Oid typid, bool *failure)
 		case REGOPERATOROID:
 		case REGCLASSOID:
 		case REGTYPEOID:
+		case REGCOLLATIONOID:
 		case REGCONFIGOID:
 		case REGDICTIONARYOID:
 		case REGROLEOID:

src/backend/utils/cache/catcache.c

@@ -239,6 +239,7 @@ GetCCHashEqFuncs(Oid keytype, CCHashFN *hashfunc, RegProcedure *eqfunc, CCFastEq
 		case REGOPERATOROID:
 		case REGCLASSOID:
 		case REGTYPEOID:
+		case REGCOLLATIONOID:
 		case REGCONFIGOID:
 		case REGDICTIONARYOID:
 		case REGROLEOID: