MDEV-21388 Wrong result of DAYNAME()=xxx in combination with condition_pushdown_for_derived=on

mysql-test/r/derived_cond_pushdown.result

@@ -10551,4 +10551,34 @@ EXPLAIN
 }
 DROP TABLE t1;
 DROP VIEW v1;
+#
+# MDEV-21388 Wrong result of DAYNAME()=xxx in combination with condition_pushdown_for_derived=on
+#
+CREATE TABLE t1 (a INT, b DATE, c INT);
+INSERT INTO t1 VALUES
+(1,'2001-01-21',345),
+(6,'2001-01-20',315),
+(6,'2001-01-20',214);
+CREATE TABLE t2 (a INT, b INT);
+INSERT INTO t2 VALUES (2,19), (7,20);
+CREATE VIEW v1 AS SELECT a, b, max(c) AS max_c FROM t1
+GROUP BY a,b HAVING max_c < 707;
+SELECT *, dayname(v1.b) FROM v1,t2 WHERE (v1.max_c>214) AND (t2.a>v1.a);
+a	b	max_c	a	b	dayname(v1.b)
+1	2001-01-21	345	2	19	Sunday
+1	2001-01-21	345	7	20	Sunday
+6	2001-01-20	315	7	20	Saturday
+SET optimizer_switch='condition_pushdown_for_derived=off';
+SELECT *, dayname(v1.b) FROM v1,t2 WHERE (v1.max_c>214) AND (t2.a>v1.a) AND dayname(v1.b)='Sunday';
+a	b	max_c	a	b	dayname(v1.b)
+1	2001-01-21	345	2	19	Sunday
+1	2001-01-21	345	7	20	Sunday
+SET optimizer_switch='condition_pushdown_for_derived=on';
+SELECT *, dayname(v1.b) FROM v1,t2 WHERE (v1.max_c>214) AND (t2.a>v1.a) AND dayname(v1.b)='Sunday';
+a	b	max_c	a	b	dayname(v1.b)
+1	2001-01-21	345	2	19	Sunday
+1	2001-01-21	345	7	20	Sunday
+DROP VIEW v1;
+DROP TABLE t1, t2;
+SET optimizer_switch=DEFAULT;
 # End of 10.2 tests

mysql-test/r/func_time.result

@@ -159,7 +159,9 @@ date_format('1999-12-31','%x-%v')	date_format('2000-01-01','%x-%v')
 1999-52	1999-52
 select dayname("1962-03-03"),dayname("1962-03-03")+0;
 dayname("1962-03-03")	dayname("1962-03-03")+0
-Saturday	5
+Saturday	0
+Warnings:
+Warning	1292	Truncated incorrect DOUBLE value: 'Saturday'
 select monthname("1972-03-04"),monthname("1972-03-04")+0;
 monthname("1972-03-04")	monthname("1972-03-04")+0
 March	0
@@ -3508,5 +3510,18 @@ v3	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VI
 DROP VIEW v1,v2,v3;
 DROP TABLE t1,t2;
 #
+# MDEV-21388 Wrong result of DAYNAME()=xxx in combination with condition_pushdown_for_derived=on
+#
+SELECT DAYNAME('2019-01-05')+0;
+DAYNAME('2019-01-05')+0
+0
+Warnings:
+Warning	1292	Truncated incorrect DOUBLE value: 'Saturday'
+SELECT CAST(DAYNAME('2019-01-05') AS SIGNED);
+CAST(DAYNAME('2019-01-05') AS SIGNED)
+0
+Warnings:
+Warning	1292	Truncated incorrect INTEGER value: 'Saturday'
+#
 # End of 10.2 tests
 #

mysql-test/t/derived_cond_pushdown.test

@@ -2140,4 +2140,32 @@ SELECT * FROM (SELECT 1 FROM v1 UNION (SELECT 1 FROM v1 WHERE @a := uuid())) dt;
 DROP TABLE t1;
 DROP VIEW v1;
 
+--echo #
+--echo # MDEV-21388 Wrong result of DAYNAME()=xxx in combination with condition_pushdown_for_derived=on
+--echo #
+
+CREATE TABLE t1 (a INT, b DATE, c INT);
+INSERT INTO t1 VALUES
+  (1,'2001-01-21',345),
+  (6,'2001-01-20',315),
+  (6,'2001-01-20',214);
+
+CREATE TABLE t2 (a INT, b INT);
+INSERT INTO t2 VALUES (2,19), (7,20);
+CREATE VIEW v1 AS SELECT a, b, max(c) AS max_c FROM t1
+  GROUP BY a,b HAVING max_c < 707;
+
+SELECT *, dayname(v1.b) FROM v1,t2 WHERE (v1.max_c>214) AND (t2.a>v1.a);
+
+SET optimizer_switch='condition_pushdown_for_derived=off';
+SELECT *, dayname(v1.b) FROM v1,t2 WHERE (v1.max_c>214) AND (t2.a>v1.a) AND dayname(v1.b)='Sunday';
+
+SET optimizer_switch='condition_pushdown_for_derived=on';
+SELECT *, dayname(v1.b) FROM v1,t2 WHERE (v1.max_c>214) AND (t2.a>v1.a) AND dayname(v1.b)='Sunday';
+
+DROP VIEW v1;
+DROP TABLE t1, t2;
+
+SET optimizer_switch=DEFAULT;
+
 --echo # End of 10.2 tests

mysql-test/t/func_time.test

@@ -1969,6 +1969,14 @@ show create view v3;
 DROP VIEW v1,v2,v3;
 DROP TABLE t1,t2;
 
+--echo #
+--echo # MDEV-21388 Wrong result of DAYNAME()=xxx in combination with condition_pushdown_for_derived=on
+--echo #
+
+SELECT DAYNAME('2019-01-05')+0;
+SELECT CAST(DAYNAME('2019-01-05') AS SIGNED);
+
+
 --echo #
 --echo # End of 10.2 tests
 --echo #

sql/item_timefunc.cc

@@ -1090,17 +1090,21 @@ longlong Item_func_yearweek::val_int()
 }
 
 
-longlong Item_func_weekday::val_int()
+static uint weekday_from_item(Item *item, bool *null_value, bool week_starts_on_sunday)
 {
-  DBUG_ASSERT(fixed == 1);
   MYSQL_TIME ltime;
-  
-  if (get_arg0_date(&ltime, TIME_NO_ZERO_DATE | TIME_NO_ZERO_IN_DATE))
+  if ((*null_value= item->get_date_with_conversion(&ltime, TIME_NO_ZERO_DATE |
+                                                           TIME_NO_ZERO_IN_DATE)))
     return 0;
+  return calc_weekday(calc_daynr(ltime.year, ltime.month, ltime.day), week_starts_on_sunday) +
+         MY_TEST(week_starts_on_sunday);
+}
 
-  return (longlong) calc_weekday(calc_daynr(ltime.year, ltime.month,
-                                            ltime.day),
-                                 odbc_type) + MY_TEST(odbc_type);
+
+longlong Item_func_weekday::val_int()
+{
+  DBUG_ASSERT(fixed == 1);
+  return (longlong) weekday_from_item(args[0], &null_value, odbc_type);
 }
 
 bool Item_func_dayname::fix_length_and_dec()
@@ -1119,7 +1123,7 @@ bool Item_func_dayname::fix_length_and_dec()
 String* Item_func_dayname::val_str(String* str)
 {
   DBUG_ASSERT(fixed == 1);
-  uint weekday=(uint) val_int();		// Always Item_func_weekday()
+  uint weekday= weekday_from_item(args[0], &null_value, false);
   const char *day_name;
   uint err;
 

sql/item_timefunc.h

@@ -410,26 +410,17 @@ class Item_func_year :public Item_int_func
 };
 
 
-class Item_func_weekday :public Item_func
+class Item_func_weekday :public Item_int_func
 {
   bool odbc_type;
 public:
   Item_func_weekday(THD *thd, Item *a, bool type_arg):
-    Item_func(thd, a), odbc_type(type_arg) { collation.set_numeric(); }
+    Item_int_func(thd, a), odbc_type(type_arg) { }
   longlong val_int();
-  double val_real() { DBUG_ASSERT(fixed == 1); return (double) val_int(); }
-  String *val_str(String *str)
-  {
-    DBUG_ASSERT(fixed == 1);
-    str->set(val_int(), &my_charset_bin);
-    return null_value ? 0 : str;
-  }
   const char *func_name() const
   {
      return (odbc_type ? "dayofweek" : "weekday");
   }
-  enum Item_result result_type () const { return INT_RESULT; }
-  enum_field_types field_type() const { return MYSQL_TYPE_LONGLONG; }
   bool fix_length_and_dec()
   {
     decimals= 0;
@@ -447,21 +438,25 @@ class Item_func_weekday :public Item_func
   { return get_item_copy<Item_func_weekday>(thd, mem_root, this); }
 };
 
-class Item_func_dayname :public Item_func_weekday
+class Item_func_dayname :public Item_str_func
 {
   MY_LOCALE *locale;
  public:
-  Item_func_dayname(THD *thd, Item *a): Item_func_weekday(thd, a, 0) {}
+  Item_func_dayname(THD *thd, Item *a): Item_str_func(thd, a) {}
   const char *func_name() const { return "dayname"; }
   String *val_str(String *str);
-  enum Item_result result_type () const { return STRING_RESULT; }
-  enum_field_types field_type() const { return MYSQL_TYPE_VARCHAR; }
   bool fix_length_and_dec();
   bool check_partition_func_processor(void *int_arg) {return TRUE;}
   bool check_vcol_func_processor(void *arg)
   {
     return mark_unsupported_function(func_name(), "()", arg, VCOL_SESSION_FUNC);
   }
+  bool check_valid_arguments_processor(void *int_arg)
+  {
+    return !has_date_args();
+  }
+  Item *get_copy(THD *thd, MEM_ROOT *mem_root)
+  { return get_item_copy<Item_func_dayname>(thd, mem_root, this); }
 };