MDEV-16926 CAST(COALESCE(year_field)) returns wrong value

mysql-test/main/type_year.result

@@ -525,5 +525,34 @@ Warnings:
 Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = 93
 DROP TABLE t1;
 #
+# MDEV-16926 CAST(COALESCE(year_field)) returns wrong value
+#
+CREATE OR REPLACE TABLE t1 (a YEAR);
+INSERT INTO t1 VALUES (1970),(1978),(2000),(2069);
+SELECT a, CAST(a AS DATE), CAST(COALESCE(a) AS DATE) FROM t1;
+a	CAST(a AS DATE)	CAST(COALESCE(a) AS DATE)
+1970	1970-00-00	1970-00-00
+1978	1978-00-00	1978-00-00
+2000	2000-00-00	2000-00-00
+2069	2069-00-00	2069-00-00
+SELECT MIN(a), MAX(a) FROM t1;
+MIN(a)	MAX(a)
+1970	2069
+DROP TABLE t1;
+CREATE OR REPLACE TABLE t1 (a YEAR(2));
+Warnings:
+Note	1287	'YEAR(2)' is deprecated and will be removed in a future release. Please use YEAR(4) instead
+INSERT INTO t1 VALUES (1970),(1978),(2000),(2069);
+SELECT a, CAST(a AS DATE), CAST(COALESCE(a) AS DATE) FROM t1;
+a	CAST(a AS DATE)	CAST(COALESCE(a) AS DATE)
+70	1970-00-00	1970-00-00
+78	1978-00-00	1978-00-00
+00	2000-00-00	2000-00-00
+69	2069-00-00	2069-00-00
+SELECT MIN(a), MAX(a) FROM t1;
+MIN(a)	MAX(a)
+70	69
+DROP TABLE t1;
+#
 # End of 10.4 tests
 #

mysql-test/main/type_year.test

@@ -278,6 +278,23 @@ SELECT * FROM t1 WHERE a=1993 and a=93;
 EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=1993 and a=93;
 DROP TABLE t1;
 
+--echo #
+--echo # MDEV-16926 CAST(COALESCE(year_field)) returns wrong value
+--echo #
+
+CREATE OR REPLACE TABLE t1 (a YEAR);
+INSERT INTO t1 VALUES (1970),(1978),(2000),(2069);
+SELECT a, CAST(a AS DATE), CAST(COALESCE(a) AS DATE) FROM t1;
+SELECT MIN(a), MAX(a) FROM t1;
+DROP TABLE t1;
+
+CREATE OR REPLACE TABLE t1 (a YEAR(2));
+INSERT INTO t1 VALUES (1970),(1978),(2000),(2069);
+SELECT a, CAST(a AS DATE), CAST(COALESCE(a) AS DATE) FROM t1;
+SELECT MIN(a), MAX(a) FROM t1;
+DROP TABLE t1;
+
+
 --echo #
 --echo # End of 10.4 tests
 --echo #

sql/field.h

@@ -2881,7 +2881,10 @@ class Field_year :public Field_tiny {
     :Field_tiny(ptr_arg, len_arg, null_ptr_arg, null_bit_arg,
 		unireg_check_arg, field_name_arg, 1, 1)
     {}
-  const Type_handler *type_handler() const { return &type_handler_year; }
+  const Type_handler *type_handler() const
+  {
+    return field_length == 2 ? &type_handler_year2 : &type_handler_year;
+  }
   Copy_func *get_copy_func(const Field *from) const
   {
     if (eq_def(from))

sql/item.cc

@@ -1328,26 +1328,6 @@ bool Item::get_date_from_int(MYSQL_TIME *ltime, ulonglong fuzzydate)
 }
 
 
-bool Item::get_date_from_year(MYSQL_TIME *ltime, ulonglong fuzzydate)
-{
-  longlong value= val_int();
-  DBUG_ASSERT(unsigned_flag || value >= 0);
-  if (max_length == 2)
-  {
-    if (value < 70)
-      value+= 2000;
-    else if (value <= 1900)
-      value+= 1900;
-  }
-  value*= 10000; /* make it YYYYMMHH */
-  if (null_value || int_to_datetime_with_warn(false, value,
-                                              ltime, fuzzydate,
-                                              field_name_or_null()))
-    return null_value|= make_zero_date(ltime, fuzzydate);
-  return null_value= false;
-}
-
-
 bool Item::get_date_from_real(MYSQL_TIME *ltime, ulonglong fuzzydate)
 {
   double value= val_real();

sql/item.h

@@ -1607,7 +1607,6 @@ class Item: public Value_source,
                        Item **ref, uint flags);
   virtual bool get_date(MYSQL_TIME *ltime, ulonglong fuzzydate)= 0;
   bool get_date_from_int(MYSQL_TIME *ltime, ulonglong fuzzydate);
-  bool get_date_from_year(MYSQL_TIME *ltime, ulonglong fuzzydate);
   bool get_date_from_real(MYSQL_TIME *ltime, ulonglong fuzzydate);
   bool get_date_from_string(MYSQL_TIME *ltime, ulonglong fuzzydate);
   bool get_time(MYSQL_TIME *ltime)
@@ -6476,9 +6475,13 @@ class Item_cache_int: public Item_cache
 class Item_cache_year: public Item_cache_int
 {
 public:
-  Item_cache_year(THD *thd): Item_cache_int(thd, &type_handler_year) { }
+  Item_cache_year(THD *thd, const Type_handler *handler)
+   :Item_cache_int(thd, handler) { }
   bool get_date(MYSQL_TIME *ltime, ulonglong fuzzydate)
-  { return get_date_from_year(ltime, fuzzydate); }
+  {
+    return null_value=
+      VYear(this).to_mysql_time_with_warn(ltime, fuzzydate, NULL);
+  }
 };
 
 

sql/item_timefunc.cc

@@ -2528,17 +2528,14 @@ bool Item_datetime_typecast::get_date(MYSQL_TIME *ltime, ulonglong fuzzy_date)
 bool Item_func_makedate::get_date(MYSQL_TIME *ltime, ulonglong fuzzy_date)
 {
   DBUG_ASSERT(fixed == 1);
-  long daynr=  (long) args[1]->val_int();
-  long year= (long) args[0]->val_int();
-  long days;
+  long year, days, daynr=  (long) args[1]->val_int();
 
-  if (args[0]->null_value || args[1]->null_value ||
-      year < 0 || year > 9999 || daynr <= 0)
+  VYear vyear(args[0]);
+  if (vyear.is_null() || args[1]->null_value || vyear.truncated() || daynr <= 0)
     goto err;
 
-  if (year < 100)
+  if ((year= (long) vyear.year()) < 100)
     year= year_2000_handling(year);
-
   days= calc_daynr(year,1,1) + daynr - 1;
   if (get_date_from_daynr(days, &ltime->year, &ltime->month, &ltime->day))
     goto err;

sql/sql_type.cc

@@ -42,6 +42,7 @@ Type_handler_olddecimal  type_handler_olddecimal;
 Type_handler_newdecimal  type_handler_newdecimal;
 
 Type_handler_year        type_handler_year;
+Type_handler_year        type_handler_year2;
 Type_handler_time        type_handler_time;
 Type_handler_date        type_handler_date;
 Type_handler_timestamp   type_handler_timestamp;
@@ -319,6 +320,45 @@ VSec6::VSec6(Item *item, const char *type_str, ulonglong limit)
 }
 
 
+Year::Year(longlong value, bool unsigned_flag, uint length)
+{
+  if ((m_truncated= (value < 0 && !unsigned_flag)))
+    m_year= 0;
+  else if (value > 9999)
+  {
+    m_truncated= true;
+    m_year= 9999;
+  }
+  else if (length == 2)
+  {
+    m_year= value < 70 ? (uint) value + 2000 :
+             value <= 1900 ? (uint) value + 1900 :
+             (uint) value;
+  }
+  else
+    m_year= (uint) value;
+  DBUG_ASSERT(m_year <= 9999);
+}
+
+
+uint Year::year_precision(const Item *item) const
+{
+  return item->type_handler() == &type_handler_year2 ? 2 : 4;
+}
+
+
+VYear::VYear(Item *item)
+ :Year_null(Year(item->val_int(), item->unsigned_flag,
+                 year_precision(item)), item->null_value)
+{ }
+
+
+VYear_op::VYear_op(Item_func_hybrid_field_type *item)
+ :Year_null(Year(item->int_op(), item->unsigned_flag,
+                 year_precision(item)), item->null_value)
+{ }
+
+
 void Time::make_from_item(Item *item, const Options opt)
 {
   if (item->get_date(this, opt.get_date_flags()))
@@ -3061,7 +3101,7 @@ Type_handler_int_result::Item_get_cache(THD *thd, const Item *item) const
 Item_cache *
 Type_handler_year::Item_get_cache(THD *thd, const Item *item) const
 {
-  return new (thd->mem_root) Item_cache_year(thd);
+  return new (thd->mem_root) Item_cache_year(thd, item->type_handler());
 }
 
 Item_cache *
@@ -3611,7 +3651,9 @@ bool Type_handler_int_result::Item_get_date(Item *item, MYSQL_TIME *ltime,
 bool Type_handler_year::Item_get_date(Item *item, MYSQL_TIME *ltime,
                                              ulonglong fuzzydate) const
 {
-  return item->get_date_from_year(ltime, fuzzydate);
+  return item->null_value=
+    VYear(item).to_mysql_time_with_warn(ltime, fuzzydate,
+                                        item->field_name_or_null());
 }
 
 
@@ -3786,6 +3828,17 @@ Type_handler_decimal_result::Item_func_hybrid_field_type_get_date(
 }
 
 
+bool
+Type_handler_year::Item_func_hybrid_field_type_get_date(
+                                             Item_func_hybrid_field_type *item,
+                                             MYSQL_TIME *ltime,
+                                             ulonglong fuzzydate) const
+{
+  return item->null_value=
+    VYear_op(item).to_mysql_time_with_warn(ltime, fuzzydate, NULL);
+}
+
+
 /***************************************************************************/
 
 

sql/sql_type.h

@@ -389,6 +389,61 @@ class Sec6_add
 };
 
 
+class Year
+{
+protected:
+  uint m_year;
+  bool m_truncated;
+  bool to_mysql_time_with_warn(MYSQL_TIME *to, ulonglong fuzzydate,
+                               const char *field_name) const
+  {
+    longlong value= m_year * 10000; // Make it YYYYMMDD
+    const ErrConvInteger str(value, true);
+    Sec6 sec(false, value, 0);
+    return sec.convert_to_mysql_time(to, fuzzydate, &str, field_name);
+  }
+  uint year_precision(const Item *item) const;
+public:
+  Year(): m_year(0), m_truncated(false) { }
+  Year(longlong value, bool unsigned_flag, uint length);
+  uint year() const { return m_year; }
+  bool truncated() const { return m_truncated; }
+};
+
+
+class Year_null: public Year
+{
+protected:
+  bool m_is_null;
+public:
+  Year_null(const Year &other, bool is_null)
+   :Year(is_null ? Year() : other),
+    m_is_null(is_null)
+  { }
+  bool is_null() const { return m_is_null; }
+  bool to_mysql_time_with_warn(MYSQL_TIME *to, ulonglong fuzzydate,
+                               const char *field_name) const
+  {
+    return m_is_null ? true :
+           Year::to_mysql_time_with_warn(to, fuzzydate, field_name);
+  }
+};
+
+
+class VYear: public Year_null
+{
+public:
+  VYear(Item *item);
+};
+
+
+class VYear_op: public Year_null
+{
+public:
+  VYear_op(Item_func_hybrid_field_type *item);
+};
+
+
 class Temporal: protected MYSQL_TIME
 {
 protected:
@@ -3323,6 +3378,9 @@ class Type_handler_year: public Type_handler_int_result
                                    uint32 flags) const;
   Item_cache *Item_get_cache(THD *thd, const Item *item) const;
   bool Item_get_date(Item *item, MYSQL_TIME *ltime, ulonglong fuzzydate) const;
+  bool Item_func_hybrid_field_type_get_date(Item_func_hybrid_field_type *item,
+                                            MYSQL_TIME *to,
+                                            ulonglong fuzzydate) const;
 };
 
 
@@ -4562,6 +4620,7 @@ extern MYSQL_PLUGIN_IMPORT Type_handler_newdecimal  type_handler_newdecimal;
 extern MYSQL_PLUGIN_IMPORT Type_handler_olddecimal  type_handler_olddecimal;
 
 extern MYSQL_PLUGIN_IMPORT Type_handler_year        type_handler_year;
+extern MYSQL_PLUGIN_IMPORT Type_handler_year        type_handler_year2;
 extern MYSQL_PLUGIN_IMPORT Type_handler_newdate     type_handler_newdate;
 extern MYSQL_PLUGIN_IMPORT Type_handler_date        type_handler_date;
 extern MYSQL_PLUGIN_IMPORT Type_handler_time        type_handler_time;