MDEV-3873 & MDEV-3876 & MDEV-3912 : Wrong result (extra rows) with ALL subquery

from a MERGE view.

The problem was in the lost ability to be null for the table of a left join if it
is a view/derived table.

It hapenned because setup_table_map(), was called earlier then we merged
the view or derived.

Fixed by propagating new maybe_null flag during Item::update_used_tables().

Change in join_outer.test and join_outer_jcl6.test appeared because
IS NULL reported no used tables (i.e. constant) for argument which could not be
NULL and new maybe_null flag was propagated for IS NULL argument (Item_field)
because table the Item_field belonged to changed its maybe_null status.

1 files changed, 2 insertions, 2 deletions

diff --git a/sql/item_geofunc.cc b/sql/item_geofunc.cc
index 522be28558f..ba330ba3b96 100644
--- a/sql/item_geofunc.cc
+++ b/sql/item_geofunc.cc
@@ -52,7 +52,7 @@ void Item_geometry_func::fix_length_and_dec()
   collation.set(&my_charset_bin);
   decimals=0;
   max_length= (uint32) 4294967295U;
-  maybe_null= 1;
+  set_persist_maybe_null(1);
 }
 
 
@@ -145,7 +145,7 @@ void Item_func_as_wkt::fix_length_and_dec()
 {
   collation.set(default_charset(), DERIVATION_COERCIBLE, MY_REPERTOIRE_ASCII);
   max_length=MAX_BLOB_WIDTH;
-  maybe_null= 1;
+  set_persist_maybe_null(1);
 }