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, 2 insertions, 2 deletions

diff --git a/sql/sql_insert.cc b/sql/sql_insert.cc
index d1db45c446e..e27cc6de073 100644
--- a/sql/sql_insert.cc
+++ b/sql/sql_insert.cc
@@ -3892,8 +3892,8 @@ void select_insert::abort_result_set() {
 Field *Item::create_field_for_create_select(THD *thd, TABLE *table)
 {
   Field *def_field, *tmp_field;
-  return create_tmp_field(thd, table, this, type(),
-                          (Item ***) 0, &tmp_field, &def_field, 0, 0, 0, 0, 0);
+  return ::create_tmp_field(thd, table, this, type(),
+                            (Item ***) 0, &tmp_field, &def_field, 0, 0, 0, 0, 0);
 }