A join patch for MDEV-10780 and MDEV-11265

MDEV-10780 Server crashes in in create_tmp_table
MDEV-11265 Access defied when CREATE VIIEW v1 AS SELECT DEFAULT(column) FROM t1

Item_default_value and Item_insert_value erroneously derive from Item_field
but forgot to override some methods that apply only to true fields,
so the server code mixes Item_{default|insert}_value instances with real
table fields (i.e. true Item_field) in some cases.
Overriding a few methods to avoid this.

TODO: we should eventually derive Item_default_value (and Item_insert_value)
directly from Item, as they don't really need the entire Item_field,
Item_ident and Item_result_field functionality.
Only the member "Field *field" related functionality is actually needed,
like val_xxx(), is_null(), get_geometry_type(), charset_for_protocol(), etc.

mysql-test/r/default.result

@@ -220,3 +220,44 @@ NULL
 10
 drop table t1, t2;
 End of 5.0 tests.
+#
+# Start of 10.0 tests
+#
+#
+# MDEV-11265 Access defied when CREATE VIIEW v1 AS SELECT DEFAULT(column) FROM t1
+#
+CREATE TABLE t1 (a INT DEFAULT 10);
+INSERT INTO t1 VALUES (11);
+CREATE VIEW v1 AS SELECT a AS a FROM t1;
+CREATE VIEW v2 AS SELECT DEFAULT(a) AS a FROM t1;
+CREATE VIEW v3 AS SELECT VALUES(a) AS a FROM t1;
+SELECT * FROM v1;
+a
+11
+SELECT * FROM v2;
+a
+10
+SELECT * FROM v3;
+a
+NULL
+UPDATE v2 SET a=123;
+ERROR HY000: Column 'a' is not updatable
+UPDATE v3 SET a=123;
+ERROR HY000: Column 'a' is not updatable
+DROP VIEW v3;
+DROP VIEW v2;
+DROP VIEW v1;
+DROP TABLE t1;
+#
+# MDEV-10780 Server crashes in in create_tmp_table
+#
+CREATE TABLE t1 (pk INT AUTO_INCREMENT PRIMARY KEY) ENGINE=MyISAM;
+INSERT INTO t1 VALUES ();
+INSERT INTO t1 VALUES ();
+SELECT DISTINCT DEFAULT (pk) FROM t1 GROUP BY RAND() WITH ROLLUP;
+DEFAULT (pk)
+0
+DROP TABLE t1;
+#
+# End of 10.0 tests
+#

mysql-test/t/default.test

@@ -166,3 +166,46 @@ drop table t1, t2;
 
 --echo End of 5.0 tests.
 
+--echo #
+--echo # Start of 10.0 tests
+--echo #
+
+--echo #
+--echo # MDEV-11265 Access defied when CREATE VIIEW v1 AS SELECT DEFAULT(column) FROM t1
+--echo #
+
+CREATE TABLE t1 (a INT DEFAULT 10);
+INSERT INTO t1 VALUES (11);
+CREATE VIEW v1 AS SELECT a AS a FROM t1;
+CREATE VIEW v2 AS SELECT DEFAULT(a) AS a FROM t1;
+CREATE VIEW v3 AS SELECT VALUES(a) AS a FROM t1;
+SELECT * FROM v1;
+SELECT * FROM v2;
+SELECT * FROM v3;
+--error ER_NONUPDATEABLE_COLUMN
+UPDATE v2 SET a=123;
+--error ER_NONUPDATEABLE_COLUMN
+UPDATE v3 SET a=123;
+DROP VIEW v3;
+DROP VIEW v2;
+DROP VIEW v1;
+DROP TABLE t1;
+
+--echo #
+--echo # MDEV-10780 Server crashes in in create_tmp_table
+--echo #
+
+# Note, the problem was not repeatable with a non-fresh connection.
+--connect (con1,127.0.0.1,root,,test)
+CREATE TABLE t1 (pk INT AUTO_INCREMENT PRIMARY KEY) ENGINE=MyISAM;
+INSERT INTO t1 VALUES ();
+INSERT INTO t1 VALUES ();
+SELECT DISTINCT DEFAULT (pk) FROM t1 GROUP BY RAND() WITH ROLLUP;
+--disconnect con1
+--connection default
+DROP TABLE t1;
+
+--echo #
+--echo # End of 10.0 tests
+--echo #
+

sql/item.h

@@ -4326,6 +4326,10 @@ class Item_default_value : public Item_field
   int save_in_field(Field *field_arg, bool no_conversions);
   table_map used_tables() const { return (table_map)0L; }
 
+  Field *get_tmp_table_field() { return 0; }
+  Item *get_tmp_table_item(THD *thd) { return this; }
+  Item_field *field_for_view_update() { return 0; }
+
   bool walk(Item_processor processor, bool walk_subquery, uchar *args)
   {
     return (arg && arg->walk(processor, walk_subquery, args)) ||
@@ -4367,6 +4371,8 @@ class Item_insert_value : public Item_field
   */
   table_map used_tables() const { return RAND_TABLE_BIT; }
 
+  Item_field *field_for_view_update() { return 0; }
+
   bool walk(Item_processor processor, bool walk_subquery, uchar *args)
   {
     return arg->walk(processor, walk_subquery, args) ||