MDEV-9407 Illegal mix of collation when using GROUP_CONCAT in a VIEW

MDEV-9408 CREATE TABLE SELECT MAX(int_column) creates different columns for table vs view

There were three almost identical pieces of the code:
- Field *Item_func::tmp_table_field();
- Field *Item_sum::create_tmp_field();
- Field *create_tmp_field_from_item();
with a difference in very small details (hence the bugs):
Only Item_func::tmp_table_field() was correct, the other two were not.
Removing the two incorrect pieces of the redundant code.
Joining these three functions/methods into a single virtual method
Item::create_tmp_field().
Additionally, moving Item::make_string_field() and
Item::tmp_table_field_from_field_type() from the public into the
protected section of the class declaration, as they are now not
needed outside of Item.

1 files changed, 36 insertions, 0 deletions

diff --git a/mysql-test/r/view.result b/mysql-test/r/view.result
index dec85fbcd4b..01a06fad00d 100644
--- a/mysql-test/r/view.result
+++ b/mysql-test/r/view.result
@@ -5878,3 +5878,39 @@ DROP TABLE t1;
 #
 # End of 10.1 tests
 #
+#
+# Start of 10.2 tests
+#
+#
+# MDEV-9408 CREATE TABLE SELECT MAX(int_column) creates different columns for table vs view
+#
+CREATE TABLE t1 (
+id int(11) NOT NULL PRIMARY KEY,
+country varchar(32),
+code int(11) default NULL
+);
+INSERT INTO t1 VALUES (1,'ITALY',100),(2,'ITALY',200),(3,'FRANCE',100), (4,'ITALY',100);
+CREATE VIEW v1 AS SELECT * FROM t1;
+CREATE TABLE t2 AS
+SELECT code, COUNT(DISTINCT country), MAX(id) FROM t1 GROUP BY code ORDER BY MAX(id);
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `code` int(11) DEFAULT NULL,
+  `COUNT(DISTINCT country)` bigint(21) NOT NULL,
+  `MAX(id)` int(11)
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+CREATE TABLE t3 AS
+SELECT code, COUNT(DISTINCT country), MAX(id) FROM v1 GROUP BY code ORDER BY MAX(id);
+SHOW CREATE TABLE t3;
+Table	Create Table
+t3	CREATE TABLE `t3` (
+  `code` int(11) DEFAULT NULL,
+  `COUNT(DISTINCT country)` bigint(21) NOT NULL,
+  `MAX(id)` int(11) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP VIEW v1;
+DROP TABLE t1,t2,t3;
+#
+# End of 10.2 tests
+#