Remove count_one_bits() in acl.c.

The only caller, select_best_grantor(), can instead use
pg_popcount64().  This isn't performance-critical code, but we
might as well use the centralized implementation.  While at it, add
some test coverage for this part of select_best_grantor().

Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/Z9GtL7Nm6hsYyJnF%40nathan

src/backend/utils/adt/acl.c

@@ -5432,24 +5432,6 @@ select_best_admin(Oid member, Oid role)
 	return admin_role;
 }
 
-
-/* does what it says ... */
-static int
-count_one_bits(AclMode mask)
-{
-	int			nbits = 0;
-
-	/* this code relies on AclMode being an unsigned type */
-	while (mask)
-	{
-		if (mask & 1)
-			nbits++;
-		mask >>= 1;
-	}
-	return nbits;
-}
-
-
 /*
  * Select the effective grantor ID for a GRANT or REVOKE operation.
  *
@@ -5532,7 +5514,7 @@ select_best_grantor(Oid roleId, AclMode privileges,
 		 */
 		if (otherprivs != ACL_NO_RIGHTS)
 		{
-			int			nnewrights = count_one_bits(otherprivs);
+			int			nnewrights = pg_popcount64(otherprivs);
 
 			if (nnewrights > nrights)
 			{

src/test/regress/expected/privileges.out

@@ -3293,3 +3293,30 @@ DROP SCHEMA reindex_test;
 DROP ROLE regress_no_maintain;
 DROP ROLE regress_maintain;
 DROP ROLE regress_maintain_all;
+-- grantor selection
+CREATE ROLE regress_grantor1;
+CREATE ROLE regress_grantor2 ROLE regress_grantor1;
+CREATE ROLE regress_grantor3;
+CREATE TABLE grantor_test1 ();
+CREATE TABLE grantor_test2 ();
+CREATE TABLE grantor_test3 ();
+GRANT SELECT ON grantor_test2 TO regress_grantor1 WITH GRANT OPTION;
+GRANT SELECT, UPDATE ON grantor_test3 TO regress_grantor2 WITH GRANT OPTION;
+SET ROLE regress_grantor1;
+GRANT SELECT, UPDATE ON grantor_test1 TO regress_grantor3;
+ERROR:  permission denied for table grantor_test1
+GRANT SELECT, UPDATE ON grantor_test2 TO regress_grantor3;
+WARNING:  not all privileges were granted for "grantor_test2"
+GRANT SELECT, UPDATE ON grantor_test3 TO regress_grantor3;
+RESET ROLE;
+SELECT * FROM information_schema.table_privileges t
+	WHERE grantor LIKE 'regress_grantor%' ORDER BY ROW(t.*);
+     grantor      |     grantee      | table_catalog | table_schema |  table_name   | privilege_type | is_grantable | with_hierarchy 
+------------------+------------------+---------------+--------------+---------------+----------------+--------------+----------------
+ regress_grantor1 | regress_grantor3 | regression    | public       | grantor_test2 | SELECT         | NO           | YES
+ regress_grantor2 | regress_grantor3 | regression    | public       | grantor_test3 | SELECT         | NO           | YES
+ regress_grantor2 | regress_grantor3 | regression    | public       | grantor_test3 | UPDATE         | NO           | NO
+(3 rows)
+
+DROP TABLE grantor_test1, grantor_test2, grantor_test3;
+DROP ROLE regress_grantor1, regress_grantor2, regress_grantor3;

src/test/regress/sql/privileges.sql

@@ -2042,3 +2042,25 @@ DROP SCHEMA reindex_test;
 DROP ROLE regress_no_maintain;
 DROP ROLE regress_maintain;
 DROP ROLE regress_maintain_all;
+
+-- grantor selection
+CREATE ROLE regress_grantor1;
+CREATE ROLE regress_grantor2 ROLE regress_grantor1;
+CREATE ROLE regress_grantor3;
+CREATE TABLE grantor_test1 ();
+CREATE TABLE grantor_test2 ();
+CREATE TABLE grantor_test3 ();
+GRANT SELECT ON grantor_test2 TO regress_grantor1 WITH GRANT OPTION;
+GRANT SELECT, UPDATE ON grantor_test3 TO regress_grantor2 WITH GRANT OPTION;
+
+SET ROLE regress_grantor1;
+GRANT SELECT, UPDATE ON grantor_test1 TO regress_grantor3;
+GRANT SELECT, UPDATE ON grantor_test2 TO regress_grantor3;
+GRANT SELECT, UPDATE ON grantor_test3 TO regress_grantor3;
+RESET ROLE;
+
+SELECT * FROM information_schema.table_privileges t
+	WHERE grantor LIKE 'regress_grantor%' ORDER BY ROW(t.*);
+
+DROP TABLE grantor_test1, grantor_test2, grantor_test3;
+DROP ROLE regress_grantor1, regress_grantor2, regress_grantor3;