MDEV-20272 PERCENTILE_DISC() crashes on a temporal type input

mysql-test/main/win_percentile.result

@@ -451,3 +451,17 @@ Lady of the Flies	20000000000.00
 Lord of the Ladybirds	30000000000.00
 Lord of the Ladybirds	30000000000.00
 DROP TABLE t2, t1;
+#
+# MDEV-20272 PERCENTILE_DISC() crashes on a temporal type input
+#
+CREATE OR REPLACE TABLE t1 (name CHAR(30), star_rating TIME);
+INSERT INTO t1 VALUES ('Lord of the Ladybirds', 5);
+INSERT INTO t1 VALUES ('Lord of the Ladybirds', 3);
+INSERT INTO t1 VALUES ('Lady of the Flies', 1);
+INSERT INTO t1 VALUES ('Lady of the Flies', 2);
+INSERT INTO t1 VALUES ('Lady of the Flies', 5);
+SELECT name, PERCENTILE_DISC(0.5)
+WITHIN GROUP (ORDER BY star_rating)
+OVER (PARTITION BY name) AS pc FROM t1;
+ERROR HY000: Numeric datatype is required for percentile_disc function
+DROP TABLE t1;

mysql-test/main/win_percentile.test

@@ -209,3 +209,20 @@ CREATE OR REPLACE TABLE t2 AS SELECT name, PERCENTILE_DISC(0.5)
 SHOW CREATE TABLE t2;
 SELECT * FROM t2 ORDER BY name, pc;
 DROP TABLE t2, t1;
+
+
+--echo #
+--echo # MDEV-20272 PERCENTILE_DISC() crashes on a temporal type input
+--echo #
+
+CREATE OR REPLACE TABLE t1 (name CHAR(30), star_rating TIME);
+INSERT INTO t1 VALUES ('Lord of the Ladybirds', 5);
+INSERT INTO t1 VALUES ('Lord of the Ladybirds', 3);
+INSERT INTO t1 VALUES ('Lady of the Flies', 1);
+INSERT INTO t1 VALUES ('Lady of the Flies', 2);
+INSERT INTO t1 VALUES ('Lady of the Flies', 5);
+--error ER_WRONG_TYPE_FOR_PERCENTILE_FUNC
+SELECT name, PERCENTILE_DISC(0.5)
+  WITHIN GROUP (ORDER BY star_rating)
+  OVER (PARTITION BY name) AS pc FROM t1;
+DROP TABLE t1;

sql/item_windowfunc.cc

@@ -172,25 +172,38 @@ void Item_window_func::split_sum_func(THD *thd, Ref_ptr_array ref_pointer_array,
 
 bool Item_window_func::check_result_type_of_order_item()
 {
-  if (only_single_element_order_list())
+  switch (window_func()->sum_func()) {
+  case Item_sum::PERCENTILE_CONT_FUNC:
   {
-    Item *src_item= window_spec->order_list->first->item[0];
-    Item_result rtype= src_item->cmp_type();
+    Item_result rtype= window_spec->order_list->first->item[0]->cmp_type();
     // TODO (varun) : support date type in percentile_cont function
     if (rtype != REAL_RESULT && rtype != INT_RESULT &&
         rtype != DECIMAL_RESULT && rtype != TIME_RESULT)
     {
       my_error(ER_WRONG_TYPE_FOR_PERCENTILE_FUNC, MYF(0), window_func()->func_name());
-      return TRUE;
+      return true;
     }
-    if (window_func()->sum_func() == Item_sum::PERCENTILE_DISC_FUNC)
+    return false;
+  }
+  case Item_sum::PERCENTILE_DISC_FUNC:
+  {
+    Item *src_item= window_spec->order_list->first->item[0];
+    Item_result rtype= src_item->cmp_type();
+    // TODO-10.5: Fix MDEV-20280 PERCENTILE_DISC() rejects temporal and string input
+    if (rtype != REAL_RESULT && rtype != INT_RESULT && rtype != DECIMAL_RESULT)
     {
-      Item_sum_percentile_disc *func=
-        static_cast<Item_sum_percentile_disc*>(window_func());
-      func->set_handler(src_item->type_handler());
-      func->Type_std_attributes::set(src_item);
-      Type_std_attributes::set(src_item);
+      my_error(ER_WRONG_TYPE_FOR_PERCENTILE_FUNC, MYF(0), window_func()->func_name());
+      return true;
     }
+    Item_sum_percentile_disc *func=
+      static_cast<Item_sum_percentile_disc*>(window_func());
+    func->set_handler(src_item->type_handler());
+    func->Type_std_attributes::set(src_item);
+    Type_std_attributes::set(src_item);
+    return false;
+  }
+  default:
+    break;
   }
   return FALSE;
 }