MDEV-20332 Wrong UNSIGNED metadata flag returned for COALESCE(unsigned_field,timestamp_field)

mysql-test/main/func_hybrid_type.result

@@ -4104,3 +4104,18 @@ c
 #
 # End of 10.4 tests
 #
+#
+# Start of 10.5 tests
+#
+#
+# MDEV-20332 Wrong UNSIGNED metadata flag returned for COALESCE(unsigned_field,timestamp_field)
+#
+CREATE TABLE t1 (a INT UNSIGNED, b TIMESTAMP);
+SELECT COALESCE(a,b) FROM t1;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def					COALESCE(a,b)	253	19	0	Y	0	39	8
+COALESCE(a,b)
+DROP TABLE t1;
+#
+# End of 10.5 tests
+#

mysql-test/main/func_hybrid_type.test

@@ -815,3 +815,24 @@ SELECT 0 + LEAST(TIME'-10:00:00',TIME'10:00:00') AS c;
 --echo #
 --echo # End of 10.4 tests
 --echo #
+
+
+--echo #
+--echo # Start of 10.5 tests
+--echo #
+
+--echo #
+--echo # MDEV-20332 Wrong UNSIGNED metadata flag returned for COALESCE(unsigned_field,timestamp_field)
+--echo #
+
+CREATE TABLE t1 (a INT UNSIGNED, b TIMESTAMP);
+--disable_ps_protocol
+--enable_metadata
+SELECT COALESCE(a,b) FROM t1;
+--disable_metadata
+--enable_ps_protocol
+DROP TABLE t1;
+
+--echo #
+--echo # End of 10.5 tests
+--echo #

sql/sql_type.cc

@@ -1201,7 +1201,7 @@ bool Type_std_attributes::aggregate_attributes_string(const char *func_name,
     max_length= find_max_octet_length(items, nitems);
   else
     fix_char_length(find_max_char_length(items, nitems));
-  unsigned_flag= count_unsigned(items, nitems) > 0;
+  unsigned_flag= false;
   decimals= max_length ? NOT_FIXED_DEC : 0;
   return false;
 }