MDEV-657 LP:873142 - GREATEST() does not always return same signness of argument types.

The patch for MDEV-8871 also fixed the problem reported in MDEV-657.
Adding the test case from the bug report.

Author: Alexander Barkov

mysql-test/r/func_hybrid_type.result

@@ -2307,5 +2307,15 @@ t1	CREATE TABLE `t1` (
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 DROP TABLE t1;
 #
+# MDEV-657 LP:873142 - GREATEST() does not always return same signness of argument types
+#
+CREATE TABLE t1 (a BIGINT(20) UNSIGNED NOT NULL PRIMARY KEY);
+INSERT INTO t1 (a) VALUES (13836376518955650385) ON DUPLICATE KEY UPDATE a=GREATEST(a,VALUES(a));
+INSERT INTO t1 (a) VALUES (13836376518955650385) ON DUPLICATE KEY UPDATE a=GREATEST(a,VALUES(a));
+SELECT * FROM t1;
+a
+13836376518955650385
+DROP TABLE t1;
+#
 # End of 10.1 tests
 #

mysql-test/t/func_hybrid_type.test

@@ -102,6 +102,15 @@ CREATE TABLE t1 AS SELECT LEAST(1.0,'10');
 SHOW CREATE TABLE t1;
 DROP TABLE t1;
 
+--echo #
+--echo # MDEV-657 LP:873142 - GREATEST() does not always return same signness of argument types
+--echo #
+CREATE TABLE t1 (a BIGINT(20) UNSIGNED NOT NULL PRIMARY KEY);
+INSERT INTO t1 (a) VALUES (13836376518955650385) ON DUPLICATE KEY UPDATE a=GREATEST(a,VALUES(a));
+INSERT INTO t1 (a) VALUES (13836376518955650385) ON DUPLICATE KEY UPDATE a=GREATEST(a,VALUES(a));
+SELECT * FROM t1;
+DROP TABLE t1;
+
 --echo #
 --echo # End of 10.1 tests
 --echo #