Fix bug lp:1002079

  
  Analysis:
  The optimizer detects an empty result through constant table optimization.
  Then it calls return_zero_rows(), which in turns calls inderctly
  Item_maxmin_subselect::no_rows_in_result(). The latter method set "value=0",
  however "value" is pointer to Item_cache, and not just an integer value.
  
  All of the Item_[maxmin | singlerow]_subselect::val_XXX methods does:
    if (forced_const)
      return value->val_real();
  which of course crashes when value is a NULL pointer.
  
  Solution:
  When the optimizer discovers an empty result set, set
  Item_singlerow_subselect::value to a FALSE constant Item instead of NULL.

1 files changed, 15 insertions, 0 deletions

diff --git a/mysql-test/t/subselect.test b/mysql-test/t/subselect.test
index b37f749b2d3..e2d829996b7 100644
--- a/mysql-test/t/subselect.test
+++ b/mysql-test/t/subselect.test
@@ -5174,6 +5174,21 @@ SELECT COUNT(f1), f2 IN (SELECT f1 FROM t1 WHERE f2 > 0) AS f4 FROM t2, t1 WHERE
 
 drop table t1,t2;
 
+--echo #
+--echo # LP BUG#1002079 Server crashes in Item_singlerow_subselect::val_int with constant table,
+--echo # HAVING, UNION in subquery
+--echo #
+
+CREATE TABLE t1 (a INT);
+INSERT INTO t1 VALUES (7),(0);
+CREATE TABLE t2 (b INT);
+
+EXPLAIN
+SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELECT 5) AND f1 = 7;
+
+SELECT SUM(a) AS f1, a AS f2 FROM (t1, t2) HAVING f2 >= ALL (SELECT 4 UNION SELECT 5) AND f1 = 7;
+
+drop table t1,t2;
 
 --echo # return optimizer switch changed in the beginning of this test
 set optimizer_switch=@subselect_tmp;