10.4 specific fixes for DEFAULT()

mysql-test/main/default.result

@@ -3412,6 +3412,7 @@ INSERT INTO t1 VALUES (),();
 SELECT 1 FROM t1 GROUP BY DEFAULT(pk);
 1
 1
+1
 DROP TABLE t1;
 #
 # MDEV-28402: ASAN heap-use-after-free in create_tmp_table,
@@ -3452,3 +3453,15 @@ drop table t1;
 #
 # End of 10.3 test
 #
+#
+# MDEV-26423: MariaDB server crash in Create_tmp_table::finalize
+#
+CREATE TABLE t1 (pk text DEFAULT length(uuid()));
+INSERT INTO t1 VALUES (),();
+SELECT 1 FROM t1 GROUP BY DEFAULT(pk);
+1
+1
+DROP TABLE t1;
+#
+# End of 10.4 test
+#

mysql-test/main/default.test

@@ -2160,3 +2160,15 @@ drop table t1;
 --echo #
 --echo # End of 10.3 test
 --echo #
+
+--echo #
+--echo # MDEV-26423: MariaDB server crash in Create_tmp_table::finalize
+--echo #
+CREATE TABLE t1 (pk text DEFAULT length(uuid()));
+INSERT INTO t1 VALUES (),();
+SELECT 1 FROM t1 GROUP BY DEFAULT(pk);
+DROP TABLE t1;
+
+--echo #
+--echo # End of 10.4 test
+--echo #

sql/item.cc

@@ -9525,6 +9525,12 @@ int Item_default_value::save_in_field(Field *field_arg, bool no_conversions)
   return Item_field::save_in_field(field_arg, no_conversions);
 }
 
+void Item_default_value::save_in_result_field(bool no_conversions)
+{
+  calculate();
+  Item_field::save_in_result_field(no_conversions);
+}
+
 double Item_default_value::val_result()
 {
   calculate();
@@ -9584,6 +9590,23 @@ table_map Item_default_value::used_tables() const
   return field->default_value->expr->used_tables();
 }
 
+bool Item_default_value::register_field_in_read_map(void *arg)
+{
+  TABLE *table= (TABLE *) arg;
+  int res= 0;
+  if (!table || (table && table == field->table))
+  {
+    if (field->default_value && field->default_value->expr)
+      res= field->default_value->expr->walk(&Item::register_field_in_read_map,1,arg);
+  }
+  else if (result_field && table == result_field->table)
+  {
+    bitmap_set_bit(table->read_set, result_field->field_index);
+  }
+
+  return res;
+}
+
 /**
   This method like the walk method traverses the item tree, but at the
   same time it can replace some nodes in the tree.

sql/item.h

@@ -6490,6 +6490,7 @@ public:
 
   bool send(Protocol *protocol, st_value *buffer);
   int save_in_field(Field *field_arg, bool no_conversions);
+  void save_in_result_field(bool no_conversions);
   bool save_in_param(THD *thd, Item_param *param)
   {
     // It should not be possible to have "EXECUTE .. USING DEFAULT(a)"
@@ -6509,6 +6510,7 @@ public:
   bool update_vcol_processor(void *arg) { return 0; }
   bool check_field_expression_processor(void *arg);
   bool check_func_default_processor(void *arg) { return true; }
+  bool register_field_in_read_map(void *arg);
 
   bool walk(Item_processor processor, bool walk_subquery, void *args)
   {

sql/sql_select.cc

@@ -18094,7 +18094,10 @@ Field *Item_default_value::create_tmp_field_ex(TABLE *table,
       as the we have to calculate the default value before we can use it.
     */
      get_tmp_field_src(src, param);
-     return tmp_table_field_from_field_type(table);
+     Field *result= tmp_table_field_from_field_type(table);
+     if (result && param->modify_item())
+       result_field= result;
+     return result;
   }
   /*
     Same code as in Item_field::create_tmp_field_ex, except no default field