1 files changed, 46 insertions, 8 deletions

diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index 90eef1ea55c..830a12ea48d 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -1466,9 +1466,36 @@ bool Item_in_optimizer::eval_not_null_tables(uchar *opt_arg)
 bool Item_in_optimizer::fix_left(THD *thd)
 {
   DBUG_ENTER("Item_in_optimizer::fix_left");
-  if ((!args[0]->fixed && args[0]->fix_fields(thd, args)) ||
-      (!cache && !(cache= Item_cache::get_cache(args[0]))))
+  /*
+    Here we will store pointer on place of main storage of left expression.
+    For usual IN (ALL/ANY) it is subquery left_expr.
+    For other cases (MAX/MIN optimization, non-transformed EXISTS (10.0))
+    it is args[0].
+  */
+  Item **ref0= args;
+  if (args[1]->type() == Item::SUBSELECT_ITEM &&
+      ((Item_subselect *)args[1])->is_in_predicate())
+  {
+    /*
+       left_expr->fix_fields() may cause left_expr to be substituted for
+       another item. (e.g. an Item_field may be changed into Item_ref). This
+       transformation is undone at the end of statement execution (e.g. the
+       Item_ref is deleted). However, Item_in_optimizer::args[0] may keep
+       the pointer to the post-transformation item. Because of that, on the
+       next execution we need to copy args[1]->left_expr again.
+    */
+    ref0= &(((Item_in_subselect *)args[1])->left_expr);
+    args[0]= ((Item_in_subselect *)args[1])->left_expr;
+  }
+  if ((!(*ref0)->fixed && (*ref0)->fix_fields(thd, ref0)) ||
+      (!cache && !(cache= Item_cache::get_cache(*ref0))))
     DBUG_RETURN(1);
+  /*
+    During fix_field() expression could be substituted.
+    So we copy changes before use
+  */
+  if (args[0] != (*ref0))
+    args[0]= (*ref0);
   DBUG_PRINT("info", ("actual fix fields"));
 
   cache->setup(args[0]);
@@ -1531,6 +1558,16 @@ bool Item_in_optimizer::fix_left(THD *thd)
 bool Item_in_optimizer::fix_fields(THD *thd, Item **ref)
 {
   DBUG_ASSERT(fixed == 0);
+  Item_subselect *sub= 0;
+  uint col;
+
+  /*
+     MAX/MIN optimization can convert the subquery into
+     expr + Item_singlerow_subselect
+   */
+  if (args[1]->type() == Item::SUBSELECT_ITEM)
+    sub= (Item_subselect *)args[1];
+
   if (fix_left(thd))
     return TRUE;
   if (args[0]->maybe_null)
@@ -1538,12 +1575,11 @@ bool Item_in_optimizer::fix_fields(THD *thd, Item **ref)
 
   if (!args[1]->fixed && args[1]->fix_fields(thd, args+1))
     return TRUE;
-
-  Item_in_subselect * sub= (Item_in_subselect *)args[1];
   if (!invisible_mode() &&
-      args[0]->cols() != sub->engine->cols())
+      ((sub && ((col= args[0]->cols()) != sub->engine->cols())) ||
+       (!sub && (args[1]->cols() != (col= 1)))))
   {
-    my_error(ER_OPERAND_COLUMNS, MYF(0), args[0]->cols());
+    my_error(ER_OPERAND_COLUMNS, MYF(0), col);
     return TRUE;
   }
   if (args[1]->maybe_null)
@@ -2756,7 +2792,8 @@ Item_func_if::str_op(String *str)
   String *res=arg->val_str(str);
   if (res)
     res->set_charset(collation.collation);
-  null_value=arg->null_value;
+  if ((null_value=arg->null_value))
+    res= NULL;
   return res;
 }
 
@@ -2767,7 +2804,8 @@ Item_func_if::decimal_op(my_decimal *decimal_value)
   DBUG_ASSERT(fixed == 1);
   Item *arg= args[0]->val_bool() ? args[1] : args[2];
   my_decimal *value= arg->val_decimal(decimal_value);
-  null_value= arg->null_value;
+  if ((null_value= arg->null_value))
+    value= NULL;
   return value;
 }