Fix for bug #6462 "Same request on same data returns different

results." a.k.a. "Proper cleanup of subqueries is missing for SET and DO
statements". (Version #2 with after-review fixes).

To perform proper cleanup for statements that can contain subqueries 
but don't have main select we must call free_undelaid_joins().


mysql-test/r/subselect.result:
  Added test for bug #6462 "Same request on same data returns different
  results." a.k.a. "Proper cleanup of subqueries is missing for SET and DO
  statements".
mysql-test/t/subselect.test:
  Added test for bug #6462 "Same request on same data returns different
  results." a.k.a. "Proper cleanup of subqueries is missing for SET and DO
  statements".
sql/set_var.cc:
  Added missing cleanup of joins used in subqueries to SET statement.
sql/sql_do.cc:
  Added missing cleanup of joins used in subqueries to DO statement.

1 files changed, 11 insertions, 6 deletions

diff --git a/sql/set_var.cc b/sql/set_var.cc
index a97506ad07c..bc0f2c2a02c 100644
--- a/sql/set_var.cc
+++ b/sql/set_var.cc
@@ -2703,13 +2703,18 @@ int sql_set_variables(THD *thd, List<set_var_base> *var_list)
   while ((var=it++))
   {
     if ((error=var->check(thd)))
-      DBUG_RETURN(error);
+      goto err;
   }
-  if (thd->net.report_error)
-    DBUG_RETURN(1);
-  it.rewind();
-  while ((var=it++))
-    error|= var->update(thd);			// Returns 0, -1 or 1
+  if (!thd->net.report_error)
+  {
+    it.rewind();
+    while ((var= it++))
+      error|= var->update(thd);         // Returns 0, -1 or 1
+  }
+  else
+    error= 1;
+err:
+  free_underlaid_joins(thd, &thd->lex->select_lex);
   DBUG_RETURN(error);
 }