BUG#834534: Assertion `0' failed in replace_where_subcondition with semijoin subquery in HAVING

- The problem was that the code that made the check whether the subquery is an AND-part of the WHERE 
  clause didn't work correctly for nested subqueries. In particular, grand-child subquery in HAVING was 
  treated as if it was in the WHERE, which eventually caused an assert when replace_where_subcondition
  looked for the subquery predicate in the WHERE and couldn't find it there.

- The fix: Removed implementation of "thd_marker approach". thd->thd_marker was used to determine the 
  location of subquery predicate: setup_conds() would set accordingly it when making the 

    {where|on_expr}->fix_fields(...)

  call so that AND-parts of the WHERE/ON clauses can determine they are the AND-parts. 
  Item_cond_or::fix_fields(), Item_func::fix_fields(), Item_subselect::fix_fields (this one was missed),
  and all other items-that-contain-items had to reset thd->thd_marker before calling fix_fields() for 
  their children items, so that the children can see they are not AND-parts of WHERE/ON.
- The "thd_marker approach" required that a lot of code in different locations maintains correct value of
  thd->thd_marker, so it was replaced with:
- The new approach with mark_as_condition_AND_part does not keep context in thd->thd_marker. Instead, 
  setup_conds() now calls

    {where|on_expr}->mark_as_condition_AND_part()

  and implementations of that function make sure that: 
   - parts of AND-expressions get the mark_as_condition_AND_part() call
   - Item_in_subselect objects record that they are AND-parts of WHERE/ON

1 files changed, 10 insertions, 4 deletions

diff --git a/sql/item_subselect.h b/sql/item_subselect.h
index f9e7a5ef568..85ce7745751 100644
--- a/sql/item_subselect.h
+++ b/sql/item_subselect.h
@@ -428,7 +428,6 @@ public:
       join nest pointer - the predicate is an AND-part of ON expression
                           of a join nest   
       NULL              - for all other locations
-    See also THD::emb_on_expr_nest.
   */
   TABLE_LIST *emb_on_expr_nest;
   /*
@@ -447,7 +446,7 @@ public:
 
   /* A bitmap of possible execution strategies for an IN predicate. */
   uchar in_strategy;
-
+   
   bool is_jtbm_merged;
 
   /*
@@ -459,7 +458,7 @@ public:
     TRUE<=>registered in the list of semijoins in outer select
   */
   bool is_registered_semijoin;
-
+  
   /*
     Used to determine how this subselect item is represented in the item tree,
     in case there is a need to locate it there and replace with something else.
@@ -489,7 +488,8 @@ public:
   Item_in_subselect()
     :Item_exists_subselect(), left_expr_cache(0), first_execution(TRUE),
      abort_on_null(0), optimizer(0),
-    pushed_cond_guards(NULL), func(NULL), in_strategy(SUBS_NOT_TRANSFORMED),
+    pushed_cond_guards(NULL), func(NULL), emb_on_expr_nest(NULL), 
+    in_strategy(SUBS_NOT_TRANSFORMED),
     is_jtbm_merged(FALSE),
     upper_item(0)
     {}
@@ -533,6 +533,12 @@ public:
     user.
   */
   int get_identifier();
+
+  void mark_as_condition_AND_part(TABLE_LIST *embedding)
+  {
+    emb_on_expr_nest= embedding;
+  }
+
   friend class Item_ref_null_helper;
   friend class Item_is_not_null_test;
   friend class Item_in_optimizer;