Unbreak comments on composite type attributes.

Report and diagnosis by Peter Eisentraut.

src/backend/catalog/objectaddress.c

@@ -473,7 +473,7 @@ get_object_address_attribute(ObjectType objtype, List *objname,
 	/* Extract relation name and open relation. */
 	attname = strVal(lfirst(list_tail(objname)));
 	relname = list_truncate(list_copy(objname), list_length(objname) - 1);
-	relation = heap_openrv(makeRangeVarFromNameList(relname), lockmode);
+	relation = relation_openrv(makeRangeVarFromNameList(relname), lockmode);
 	reloid = RelationGetRelid(relation);
 
 	/* Look up attribute and construct return value. */

src/test/regress/expected/create_type.out

@@ -97,6 +97,10 @@ COMMENT ON TYPE bad IS 'bad comment';
 ERROR:  type "bad" does not exist
 COMMENT ON TYPE default_test_row IS 'good comment';
 COMMENT ON TYPE default_test_row IS NULL;
+COMMENT ON COLUMN default_test_row.nope IS 'bad comment';
+ERROR:  column "nope" of relation "default_test_row" does not exist
+COMMENT ON COLUMN default_test_row.f1 IS 'good comment';
+COMMENT ON COLUMN default_test_row.f1 IS NULL;
 -- Check shell type create for existing types
 CREATE TYPE text_w_default;		-- should fail
 ERROR:  type "text_w_default" already exists

src/test/regress/sql/create_type.sql

@@ -95,6 +95,9 @@ SELECT * FROM get_default_test();
 COMMENT ON TYPE bad IS 'bad comment';
 COMMENT ON TYPE default_test_row IS 'good comment';
 COMMENT ON TYPE default_test_row IS NULL;
+COMMENT ON COLUMN default_test_row.nope IS 'bad comment';
+COMMENT ON COLUMN default_test_row.f1 IS 'good comment';
+COMMENT ON COLUMN default_test_row.f1 IS NULL;
 
 -- Check shell type create for existing types
 CREATE TYPE text_w_default;		-- should fail