Bug#46051: Incorrectly market field caused wrong result.

In a subselect all fields from outer selects are marked as dependent on
selects they are belong to. In some cases optimizer substitutes it for an
equivalent expression. For example "a_field IN (SELECT outer_field)" is
substituted with "a_field = outer_field". As we moved the outer_field to the
upper select it's not really outer anymore. But it was left marked as outer.
If exists an index over a_field optimizer choose wrong execution plan and thus
return wrong result.

Now the Item_in_subselect::single_value_transformer function removes dependent
marking from fields when a subselect is optimized away.

mysql-test/r/subselect.result:
  Added a test case for the bug#46051.
mysql-test/t/subselect.test:
  Added a test case for the bug#46051.
sql/item_subselect.cc:
  Bug#46051: Incorrectly market field caused wrong result.
  Now the Item_in_subselect::single_value_transformer function removes dependent
  marking from fields when a subselect is optimized away.

1 files changed, 4 insertions, 0 deletions

diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc
index 13eeba3ea27..805669b3cfa 100644
--- a/sql/item_subselect.cc
+++ b/sql/item_subselect.cc
@@ -1145,6 +1145,10 @@ Item_in_subselect::single_value_transformer(JOIN *join,
       else
       {
 	// it is single select without tables => possible optimization
+        // remove the dependence mark since the item is moved to upper
+        // select and is not outer anymore.
+        item->walk(&Item::remove_dependence_processor,
+                           (byte *) select_lex->outer_select());
 	item= func->create(left_expr, item);
 	// fix_field of item will be done in time of substituting
 	substitution= item;