MDEV-4848 Wrong metadata or column type for LEAST(1.0,'10')

MDEV-8873 Wrong field type or metadata for LEAST(int_column,string_column)

mysql-test/t/func_hybrid_type.test

@@ -57,6 +57,50 @@ INSERT INTO t1 VALUES (0x32,0x32);
 --source include/func_hybrid_type.inc
 DROP TABLE t1;
 
+--echo #
+CREATE TABLE t1 (a FLOAT, b SMALLINT);
+INSERT INTO t1 VALUES (1,-32678);
+--source include/func_hybrid_type.inc
+DROP TABLE t1;
+
+--echo #
+CREATE TABLE t1 (a VARCHAR(10), b ENUM('b'));
+INSERT INTO t1 VALUES ('a','b');
+--source include/func_hybrid_type.inc
+DROP TABLE t1;
+
+--echo #
+CREATE TABLE t1 (a INT, b YEAR);
+INSERT INTO t1 VALUES (-2147483648,2015);
+--source include/func_hybrid_type.inc
+DROP TABLE t1;
+
+--echo #
+CREATE TABLE t1 (a INT UNSIGNED, b YEAR);
+INSERT INTO t1 VALUES (4294967295,2015);
+--source include/func_hybrid_type.inc
+DROP TABLE t1;
+
+
+--echo #
+--echo # MDEV-8873 Wrong field type or metadata for LEAST(int_column,string_column)
+--echo #
+CREATE TABLE t1 (a INT, b VARCHAR(10));
+INSERT INTO t1 VALUES (-2147483648,'100x');
+--source include/func_hybrid_type.inc
+DROP TABLE t1;
+
+--echo #
+--echo # MDEV-4848 Wrong metadata or column type for LEAST(1.0,'10')
+--echo #
+--disable_ps_protocol
+--enable_metadata
+SELECT LEAST(1.0,'10');
+--disable_metadata
+--enable_ps_protocol
+CREATE TABLE t1 AS SELECT LEAST(1.0,'10');
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
 
 --echo #
 --echo # End of 10.1 tests

sql/item_func.cc

@@ -2833,7 +2833,8 @@ void Item_func_min_max::fix_length_and_dec()
   maybe_null=0;
   thd= current_thd;
   compare_as_dates= find_date_time_item(args, arg_count, 0);
-  cmp_type=args[0]->result_type();
+  Item_result tmp_cmp_type= args[0]->cmp_type();
+  uint string_type_count= 0;
 
   for (uint i=0 ; i < arg_count ; i++)
   {
@@ -2843,14 +2844,39 @@ void Item_func_min_max::fix_length_and_dec()
     unsigned_count+= args[i]->unsigned_flag;
     if (args[i]->maybe_null)
       maybe_null= 1;
-    cmp_type= item_cmp_type(cmp_type,args[i]->result_type());
+    tmp_cmp_type= item_cmp_type(tmp_cmp_type, args[i]->cmp_type());
+    string_type_count+= args[i]->cmp_type() == STRING_RESULT;
   }
   unsigned_flag= unsigned_count == arg_count; // if all args are unsigned
-  if (cmp_type == STRING_RESULT)
+
+  switch (tmp_cmp_type) {
+  case TIME_RESULT:
+    // At least one temporal argument was found.
+    collation.set_numeric();
+    set_handler_by_field_type(compare_as_dates->field_type());
+    if (mysql_type_to_time_type(Item_func_min_max::field_type()) ==
+        MYSQL_TIMESTAMP_DATE)
+      decimals= 0;
+    else
+      set_if_smaller(decimals, TIME_SECOND_PART_DIGITS);
+    break;
+
+  case STRING_RESULT:
+    /*
+      All arguments are of string-alike types:
+        CHAR, VARCHAR, TEXT, BINARY, VARBINARY, BLOB, SET, ENUM
+      No numeric and no temporal types were found.
+    */
     agg_arg_charsets_for_string_result_with_comparison(collation,
                                                        args, arg_count);
-  else if (cmp_type == INT_RESULT)
-  {
+    set_handler_by_field_type(agg_field_type(args, arg_count, false));
+    break;
+
+  case INT_RESULT:
+    /*
+       All arguments have INT-alike types:
+       TINY, SHORT, LONG, LONGLONG, INT24, YEAR, BIT.
+    */
     collation.set_numeric();
     fix_char_length(my_decimal_precision_to_length_no_truncation(max_int_part +
                                                                  decimals,
@@ -2862,32 +2888,45 @@ void Item_func_min_max::fix_length_and_dec()
         If all args are of INT-alike type, but have different unsigned_flag,
         then change type to DECIMAL.
       */
-      cmp_type= DECIMAL_RESULT;
-      cached_field_type= MYSQL_TYPE_NEWDECIMAL;
-      return;
+      set_handler_by_field_type(MYSQL_TYPE_NEWDECIMAL);
     }
-  }
-  else if (cmp_type == DECIMAL_RESULT)
-  {
+    else
+    {
+      /*
+        There are only INT-alike arguments with equal unsigned_flag.
+        Aggregate types to get the best covering type.
+        Treat BIT as LONGLONG when aggregating to non-BIT types.
+        Possible final type: TINY, SHORT, LONG, LONGLONG, INT24, YEAR, BIT.
+      */
+      set_handler_by_field_type(agg_field_type(args, arg_count, true));
+    }
+    break;
+
+  case DECIMAL_RESULT:
+    // All arguments are of DECIMAL type
     collation.set_numeric();
     fix_char_length(my_decimal_precision_to_length_no_truncation(max_int_part +
                                                                  decimals,
                                                                  decimals,
                                                                  unsigned_flag));
-  }
-  else if (cmp_type == REAL_RESULT)
-    fix_char_length(float_length(decimals));
+    set_handler_by_field_type(MYSQL_TYPE_NEWDECIMAL);
+    break;
 
-  if (compare_as_dates)
-  {
-    cached_field_type= compare_as_dates->field_type();
-    if (mysql_type_to_time_type(cached_field_type) == MYSQL_TIMESTAMP_DATE)
-      decimals= 0;
-    else
-      set_if_smaller(decimals, TIME_SECOND_PART_DIGITS);
+  case ROW_RESULT:
+    DBUG_ASSERT(0);
+    // Pass through
+  case REAL_RESULT:
+    collation.set_numeric();
+    fix_char_length(float_length(decimals));
+    /*
+      Set type to DOUBLE, as Item_func::tmp_table_field() does not
+      distinguish between DOUBLE and FLOAT and always creates Field_double.
+      Perhaps we should eventually change this to use agg_field_type() here,
+      and fix Item_func::tmp_table_field() to create Field_float when possible.
+    */
+    set_handler_by_field_type(MYSQL_TYPE_DOUBLE);
+    break;
   }
-  else
-    cached_field_type= agg_field_type(args, arg_count, false);
 }
 
 
@@ -2964,7 +3003,7 @@ String *Item_func_min_max::val_str(String *str)
   DBUG_ASSERT(fixed == 1);
   if (compare_as_dates)
     return val_string_from_date(str);
-  switch (cmp_type) {
+  switch (Item_func_min_max::result_type()) {
   case INT_RESULT:
     return val_string_from_int(str);
   case DECIMAL_RESULT:

sql/item_func.h

@@ -986,19 +986,28 @@ public:
 };
 
 
-class Item_func_min_max :public Item_func
+/**
+  Item_func_min_max does not derive from Item_func_hybrid_field_type
+  because the way how its methods val_xxx() and get_date() work depend
+  not only by its arguments, but also on the context in which
+  LEAST() and GREATEST() appear.
+  For example, using Item_func_min_max in a CAST like this:
+    CAST(LEAST('11','2') AS SIGNED)
+  forces Item_func_min_max to compare the arguments as numbers rather
+  than strings.
+  Perhaps this should be changed eventually (see MDEV-5893).
+*/
+class Item_func_min_max :public Item_func,
+                         public Type_handler_hybrid_field_type
 {
-  Item_result cmp_type;
   String tmp_value;
   int cmp_sign;
   /* An item used for issuing warnings while string to DATETIME conversion. */
   Item *compare_as_dates;
   THD *thd;
-protected:
-  enum_field_types cached_field_type;
 public:
   Item_func_min_max(THD *thd, List<Item> &list, int cmp_sign_arg):
-    Item_func(thd, list), cmp_type(INT_RESULT), cmp_sign(cmp_sign_arg),
+    Item_func(thd, list), cmp_sign(cmp_sign_arg),
     compare_as_dates(0) {}
   double val_real();
   longlong val_int();
@@ -1006,8 +1015,12 @@ public:
   my_decimal *val_decimal(my_decimal *);
   bool get_date(MYSQL_TIME *res, ulonglong fuzzy_date);
   void fix_length_and_dec();
-  enum Item_result result_type () const { return cmp_type; }
-  enum_field_types field_type() const { return cached_field_type; }
+  enum Item_result cmp_type() const
+  { return Type_handler_hybrid_field_type::cmp_type(); }
+  enum Item_result result_type() const
+  { return Type_handler_hybrid_field_type::result_type(); }
+  enum_field_types field_type() const
+  { return Type_handler_hybrid_field_type::field_type(); }
 };
 
 class Item_func_min :public Item_func_min_max