Fix for bug #32558: group by null-returning expression with rollup causes crash

Problem: setting Item_func_rollup_const::null_value property to argument's null_value
before (without) the argument evaluation may result in a crash due to wrong null_value.

Fix: use is_null() to set Item_func_rollup_const::null_value instead as it evaluates
the argument if necessary and returns a proper value.


mysql-test/r/olap.result:
  Fix for bug #32558: group by null-returning expression with rollup causes crash
    - test result.
mysql-test/t/olap.test:
  Fix for bug #32558: group by null-returning expression with rollup causes crash
    - test case.
sql/item_func.h:
  Fix for bug #32558: group by null-returning expression with rollup causes crash
    - use args[0]->is_null() to obtain Item_func_rollup_const::null_value 
      instead of args[0]->null_value as it's not set in advance in case of 
      constant functions.

1 files changed, 9 insertions, 0 deletions

diff --git a/mysql-test/t/olap.test b/mysql-test/t/olap.test
index 1ac99d9c39f..d1e40024733 100644
--- a/mysql-test/t/olap.test
+++ b/mysql-test/t/olap.test
@@ -367,3 +367,12 @@ select count(a) from t1 group by null with rollup;
 drop table t1;
 --echo ##############################################################
 
+#
+# Bug #32558: group by null-returning expression with rollup causes crash
+#
+CREATE TABLE t1(a INT);
+INSERT INTO t1 VALUES(0);
+SELECT 1 FROM t1 GROUP BY (DATE(NULL)) WITH ROLLUP;
+DROP TABLE t1;
+
+--echo End of 5.0 tests