parse negative numbers into one item

use Item->neg to convert generate negative Item_num's
instead of Item_func_neg(Item_num).

Based on the following commit:

  Author: Monty <monty@mariadb.org>
  Date:   Mon May 30 22:44:00 2016 +0300

    Make negative number their own token
    The negation (-) operator will call Item->neg() one underlying numeric constants
    and remove itself (like the NOT() function does today for other NOT functions.

    This simplifies things
    - -1 is not anymore an expression but a basic_const_item
      - improves optimizer
      - DEFAULT -1 doesn't need special handling anymore
      - When we add DEFAULT expressions, -1 will be treated exactly like 1
    - printing of items doesn't anymore put braces around all negative numbers

    Other things fixed:
    - Fixed that longlong converted to decimal's has a more appropriate size
    - Fixed that "-0.0" read into a decimal is interpreted as 0.0

4 files changed, 70 insertions, 19 deletions

diff --git a/sql/field.cc b/sql/field.cc
index 0e2bc724db0..f15e9979ff2 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -9769,12 +9769,6 @@ bool Column_definition::check(THD *thd)
     }
   }
 
-  if (length > MAX_FIELD_BLOBLENGTH)
-  {
-    my_error(ER_TOO_BIG_DISPLAYWIDTH, MYF(0), field_name, MAX_FIELD_BLOBLENGTH);
-    DBUG_RETURN(TRUE);
-  }
-
   if (def)
   {
     /*
@@ -10080,6 +10074,12 @@ bool Column_definition::check(THD *thd)
               field_name, max_field_charlength); /* purecov: inspected */
     DBUG_RETURN(TRUE);
   }
+  else if (length > MAX_FIELD_BLOBLENGTH)
+  {
+    my_error(ER_TOO_BIG_DISPLAYWIDTH, MYF(0), field_name, MAX_FIELD_BLOBLENGTH);
+    DBUG_RETURN(1);
+  }
+
   if ((~allowed_type_modifier) & flags & conditional_type_modifiers)
   {
     my_error(ER_WRONG_FIELD_SPEC, MYF(0), field_name);
diff --git a/sql/item.cc b/sql/item.cc
index 6566f3ca533..05d4cc86f7a 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -5998,9 +5998,64 @@ Item *Item_int_with_ref::clone_item(THD *thd)
 }
 
 
-Item_num *Item_uint::neg(THD *thd)
+Item *Item::neg(THD *thd)
 {
-  Item_decimal *item= new (thd->mem_root) Item_decimal(thd, value, 1);
+  return new (thd->mem_root) Item_func_neg(thd, this);
+}
+
+Item *Item_int::neg(THD *thd)
+{
+  /*
+    The following if should never be true with code generated by
+    our parser as LONGLONG_MIN values will be stored as decimal.
+    The code is here in case someone generates an int from inside
+    MariaDB
+  */
+  if (unlikely(value == LONGLONG_MIN))
+  {
+    /* Precision for int not big enough; Convert constant to decimal */
+    Item_decimal *item= new (thd->mem_root) Item_decimal(thd, value, 0);
+    return item ? item->neg(thd) : item;
+  }
+  if (value > 0)
+    max_length++;
+  else if (value < 0 && max_length)
+    max_length--;
+  value= -value;
+  name= 0;
+  return this;
+}
+
+Item *Item_decimal::neg(THD *thd)
+{
+  my_decimal_neg(&decimal_value);
+  unsigned_flag= 0;
+  name= 0;
+  max_length= my_decimal_precision_to_length_no_truncation(
+                      decimal_value.intg + decimals, decimals, unsigned_flag);
+  return this;
+}
+
+Item *Item_float::neg(THD *thd)
+{
+  if (value > 0)
+    max_length++;
+  else if (value < 0 && max_length)
+    max_length--;
+  value= -value;
+  name= presentation= 0 ;
+  return this;
+}
+
+Item *Item_uint::neg(THD *thd)
+{
+  Item_decimal *item;
+  if (((ulonglong)value) <= LONGLONG_MAX)
+    return new (thd->mem_root) Item_int(thd, -value, max_length+1);
+  if (value == LONGLONG_MIN)
+    return new (thd->mem_root) Item_int(thd, value, max_length+1);
+  if (!(item= new (thd->mem_root) Item_decimal(thd, value, 1)))
+    return 0;
   return item->neg(thd);
 }
 
diff --git a/sql/item.h b/sql/item.h
index 67d683b15ff..22e44719706 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -1846,6 +1846,8 @@ public:
   /* how much position should be reserved for Exists2In transformation */
   virtual uint exists2in_reserved_items() { return 0; };
 
+  virtual Item *neg(THD *thd);
+
   /**
     Inform the item that it is located under a NOT, which is a top-level item.
   */
@@ -2261,7 +2263,6 @@ class Item_num: public Item_basic_constant
 {
 public:
   Item_num(THD *thd): Item_basic_constant(thd) { collation.set_numeric(); }
-  virtual Item_num *neg(THD *thd)= 0;
   Item *safe_charset_converter(THD *thd, CHARSET_INFO *tocs);
   bool check_partition_func_processor(uchar *int_arg) { return FALSE;}
   bool check_vcol_func_processor(uchar *arg) { return FALSE;}
@@ -2834,7 +2835,7 @@ public:
   bool basic_const_item() const { return 1; }
   Item *clone_item(THD *thd);
   virtual void print(String *str, enum_query_type query_type);
-  Item_num *neg(THD *thd) { value= -value; return this; }
+  Item *neg(THD *thd);
   uint decimal_precision() const
   { return (uint) (max_length - MY_TEST(value < 0)); }
   bool eq(const Item *item, bool binary_cmp) const
@@ -2855,7 +2856,7 @@ public:
   String *val_str(String*);
   Item *clone_item(THD *thd);
   virtual void print(String *str, enum_query_type query_type);
-  Item_num *neg(THD *thd);
+  Item *neg(THD *thd);
   uint decimal_precision() const { return max_length; }
 };
 
@@ -2899,12 +2900,7 @@ public:
   bool basic_const_item() const { return 1; }
   Item *clone_item(THD *thd);
   virtual void print(String *str, enum_query_type query_type);
-  Item_num *neg(THD *thd)
-  {
-    my_decimal_neg(&decimal_value);
-    unsigned_flag= !decimal_value.sign();
-    return this;
-  }
+  Item *neg(THD *thd);
   uint decimal_precision() const { return decimal_value.precision(); }
   bool eq(const Item *, bool binary_cmp) const;
   void set_decimal_value(my_decimal *value_par);
@@ -2954,7 +2950,7 @@ public:
   my_decimal *val_decimal(my_decimal *);
   bool basic_const_item() const { return 1; }
   Item *clone_item(THD *thd);
-  Item_num *neg(THD *thd) { value= -value; return this; }
+  Item *neg(THD *thd);
   virtual void print(String *str, enum_query_type query_type);
   bool eq(const Item *item, bool binary_cmp) const
   { return real_eq(value, item); }
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 7ab11716f93..c971373d31b 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -9461,7 +9461,7 @@ simple_expr:
           }
         | '-' simple_expr %prec NEG
           {
-            $$= new (thd->mem_root) Item_func_neg(thd, $2);
+            $$= $2->neg(thd);
             if ($$ == NULL)
               MYSQL_YYABORT;
           }