Don't allow composite type to be member of itself via multirange

CheckAttributeType() checks that a composite type is not made a member
of itself with ALTER TABLE ADD COLUMN or ALTER TYPE ADD ATTRIBUTE,
even indirectly via a domain, array, another composite type or a range
type. But it missed checking for multiranges. That was a simple
oversight when multiranges were added.

Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://www.postgresql.org/message-id/93ce56cd-02a6-4db1-8224-c8999372facc@iki.fi
Backpatch-through: 14

src/backend/catalog/heap.c

@@ -654,6 +654,16 @@ CheckAttributeType(const char *attname,
 						   containing_rowtypes,
 						   flags);
 	}
+	else if (att_typtype == TYPTYPE_MULTIRANGE)
+	{
+		/*
+		 * If it's a multirange, recurse to check its plain range type.
+		 */
+		CheckAttributeType(attname, get_multirange_range(atttypid),
+						   InvalidOid,	/* range types are not collatable */
+						   containing_rowtypes,
+						   flags);
+	}
 	else if (OidIsValid((att_typelem = get_element_type(atttypid))))
 	{
 		/*

src/test/regress/expected/multirangetypes.out

@@ -3297,6 +3297,9 @@ select *, row_to_json(upper(t)) as u from
  {["(5,6)","(7,8)")} | {"a":7,"b":8}
 (2 rows)
 
+-- this must be rejected to avoid self-inclusion issues:
+alter type two_ints add attribute c two_ints_multirange;
+ERROR:  composite type two_ints cannot be made a member of itself
 drop type two_ints cascade;
 NOTICE:  drop cascades to type two_ints_range
 --

src/test/regress/sql/multirangetypes.sql

@@ -815,6 +815,9 @@ select *, row_to_json(upper(t)) as u from
   (values (two_ints_multirange(two_ints_range(row(1,2), row(3,4)))),
           (two_ints_multirange(two_ints_range(row(5,6), row(7,8))))) v(t);
 
+-- this must be rejected to avoid self-inclusion issues:
+alter type two_ints add attribute c two_ints_multirange;
+
 drop type two_ints cascade;
 
 --