MDEV-8049 name_const() is not consistent about its signess

mysql-test/main/func_misc.result

@@ -1562,3 +1562,23 @@ Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is
 def					INET_ATON("255.255.255.255.255.255.255.255")	8	21	20	Y	32928	0	63
 INET_ATON("255.255.255.255.255.255.255.255")
 18446744073709551615
+#
+# MDEV-8049 name_const() is not consistent about its signess
+#
+SELECT 18446744073709551615 AS c1, name_const('a',18446744073709551615) AS c2;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def					c1	8	20	20	N	32929	0	63
+def					c2	8	20	20	Y	32928	0	63
+c1	c2
+18446744073709551615	18446744073709551615
+CREATE TABLE t1 AS SELECT 18446744073709551615 AS c1, name_const('a',18446744073709551615) AS c2;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `c1` bigint(20) unsigned NOT NULL,
+  `c2` bigint(20) unsigned DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+SELECT * FROM t1;
+c1	c2
+18446744073709551615	18446744073709551615
+DROP TABLE t1;

mysql-test/main/func_misc.test

@@ -1203,3 +1203,18 @@ SELECT INET_ATON("255.255.255.255.255.255.255.255");
 
 --enable_ps_protocol
 --disable_metadata
+
+--echo #
+--echo # MDEV-8049 name_const() is not consistent about its signess
+--echo #
+
+--enable_metadata
+--disable_ps_protocol
+SELECT 18446744073709551615 AS c1, name_const('a',18446744073709551615) AS c2;
+--enable_ps_protocol
+--disable_metadata
+
+CREATE TABLE t1 AS SELECT 18446744073709551615 AS c1, name_const('a',18446744073709551615) AS c2;
+SHOW CREATE TABLE t1;
+SELECT * FROM t1;
+DROP TABLE t1;

sql/item.cc

@@ -2267,6 +2267,7 @@ bool Item_name_const::fix_fields(THD *thd, Item **ref)
     collation.set(value_item->collation.collation, DERIVATION_IMPLICIT);
   max_length= value_item->max_length;
   decimals= value_item->decimals;
+  unsigned_flag= value_item->unsigned_flag;
   fixed= 1;
   return FALSE;
 }