A helper patch for "MDEV-8228 Move Item_func_like out of Item_bool_func2"

- Changing Comp_creator::create() and create_swap() to return
  Item_bool_rowready_func2 instead of Item_bool_func2, as they
  can never return neither Item_func_like nor Item_func_xor

- Changing the first argument of Comp_create::create() and create_swap()
  from THD to MEM_ROOT, so the method implementations can now reside in
  item_cmpfunc.h instead of item_cmpfunc.cc and thus make the code slightly
  easier to read.

sql/item_cmpfunc.cc

@@ -264,66 +264,6 @@ static void my_coll_agg_error(DTCollation &c1, DTCollation &c2,
 }
 
 
-Item_bool_func2* Eq_creator::create(THD *thd, Item *a, Item *b) const
-{
-  return new (thd->mem_root) Item_func_eq(a, b);
-}
-
-Item_bool_func2* Eq_creator::create_swap(THD *thd, Item *a, Item *b) const
-{
-  return new (thd->mem_root) Item_func_eq(b, a);
-}
-
-Item_bool_func2* Ne_creator::create(THD *thd, Item *a, Item *b) const
-{
-  return new (thd->mem_root) Item_func_ne(a, b);
-}
-
-Item_bool_func2* Ne_creator::create_swap(THD *thd, Item *a, Item *b) const
-{
-  return new (thd->mem_root) Item_func_ne(b, a);
-}
-
-Item_bool_func2* Gt_creator::create(THD *thd, Item *a, Item *b) const
-{
-  return new (thd->mem_root) Item_func_gt(a, b);
-}
-
-Item_bool_func2* Gt_creator::create_swap(THD *thd, Item *a, Item *b) const
-{
-  return new (thd->mem_root) Item_func_lt(b, a);
-}
-
-Item_bool_func2* Lt_creator::create(THD *thd, Item *a, Item *b) const
-{
-  return new (thd->mem_root) Item_func_lt(a, b);
-}
-
-Item_bool_func2* Lt_creator::create_swap(THD *thd, Item *a, Item *b) const
-{
-  return new (thd->mem_root) Item_func_gt(b, a);
-}
-
-Item_bool_func2* Ge_creator::create(THD *thd, Item *a, Item *b) const
-{
-  return new (thd->mem_root) Item_func_ge(a, b);
-}
-
-Item_bool_func2* Ge_creator::create_swap(THD *thd, Item *a, Item *b) const
-{
-  return new (thd->mem_root) Item_func_le(b, a);
-}
-
-Item_bool_func2* Le_creator::create(THD *thd, Item *a, Item *b) const
-{
-  return new (thd->mem_root) Item_func_le(a, b);
-}
-
-Item_bool_func2* Le_creator::create_swap(THD *thd, Item *a, Item *b) const
-{
-  return new (thd->mem_root) Item_func_ge(b, a);
-}
-
 /*
   Test functions
   Most of these  returns 0LL if false and 1LL if true and

sql/item_cmpfunc.h

@@ -289,96 +289,6 @@ public:
   void reset_cache() { cache= NULL; }
 };
 
-class Comp_creator
-{
-public:
-  Comp_creator() {}                           /* Remove gcc warning */
-  virtual ~Comp_creator() {}                  /* Remove gcc warning */
-  /**
-    Create operation with given arguments.
-  */
-  virtual Item_bool_func2* create(THD *thd, Item *a, Item *b) const = 0;
-  /**
-    Create operation with given arguments in swap order.
-  */
-  virtual Item_bool_func2* create_swap(THD *thd, Item *a, Item *b) const = 0;
-  virtual const char* symbol(bool invert) const = 0;
-  virtual bool eqne_op() const = 0;
-  virtual bool l_op() const = 0;
-};
-
-class Eq_creator :public Comp_creator
-{
-public:
-  Eq_creator() {}                             /* Remove gcc warning */
-  virtual ~Eq_creator() {}                    /* Remove gcc warning */
-  virtual Item_bool_func2* create(THD *thd, Item *a, Item *b) const;
-  virtual Item_bool_func2* create_swap(THD *thd, Item *a, Item *b) const;
-  virtual const char* symbol(bool invert) const { return invert? "<>" : "="; }
-  virtual bool eqne_op() const { return 1; }
-  virtual bool l_op() const { return 0; }
-};
-
-class Ne_creator :public Comp_creator
-{
-public:
-  Ne_creator() {}                             /* Remove gcc warning */
-  virtual ~Ne_creator() {}                    /* Remove gcc warning */
-  virtual Item_bool_func2* create(THD *thd, Item *a, Item *b) const;
-  virtual Item_bool_func2* create_swap(THD *thd, Item *a, Item *b) const;
-  virtual const char* symbol(bool invert) const { return invert? "=" : "<>"; }
-  virtual bool eqne_op() const { return 1; }
-  virtual bool l_op() const { return 0; }
-};
-
-class Gt_creator :public Comp_creator
-{
-public:
-  Gt_creator() {}                             /* Remove gcc warning */
-  virtual ~Gt_creator() {}                    /* Remove gcc warning */
-  virtual Item_bool_func2* create(THD *thd, Item *a, Item *b) const;
-  virtual Item_bool_func2* create_swap(THD *thd, Item *a, Item *b) const;
-  virtual const char* symbol(bool invert) const { return invert? "<=" : ">"; }
-  virtual bool eqne_op() const { return 0; }
-  virtual bool l_op() const { return 0; }
-};
-
-class Lt_creator :public Comp_creator
-{
-public:
-  Lt_creator() {}                             /* Remove gcc warning */
-  virtual ~Lt_creator() {}                    /* Remove gcc warning */
-  virtual Item_bool_func2* create(THD *thd, Item *a, Item *b) const;
-  virtual Item_bool_func2* create_swap(THD *thd, Item *a, Item *b) const;
-  virtual const char* symbol(bool invert) const { return invert? ">=" : "<"; }
-  virtual bool eqne_op() const { return 0; }
-  virtual bool l_op() const { return 1; }
-};
-
-class Ge_creator :public Comp_creator
-{
-public:
-  Ge_creator() {}                             /* Remove gcc warning */
-  virtual ~Ge_creator() {}                    /* Remove gcc warning */
-  virtual Item_bool_func2* create(THD *thd, Item *a, Item *b) const;
-  virtual Item_bool_func2* create_swap(THD *thd, Item *a, Item *b) const;
-  virtual const char* symbol(bool invert) const { return invert? "<" : ">="; }
-  virtual bool eqne_op() const { return 0; }
-  virtual bool l_op() const { return 0; }
-};
-
-class Le_creator :public Comp_creator
-{
-public:
-  Le_creator() {}                             /* Remove gcc warning */
-  virtual ~Le_creator() {}                    /* Remove gcc warning */
-  virtual Item_bool_func2* create(THD *thd, Item *a, Item *b) const;
-  virtual Item_bool_func2* create_swap(THD *thd, Item *a, Item *b) const;
-  virtual const char* symbol(bool invert) const { return invert? ">" : "<="; }
-  virtual bool eqne_op() const { return 0; }
-  virtual bool l_op() const { return 1; }
-};
-
 class Item_bool_func2 :public Item_bool_func
 {						/* Bool with 2 string args */
 protected:
@@ -2248,6 +2158,135 @@ longlong get_datetime_value(THD *thd, Item ***item_arg, Item **cache_arg,
 bool get_mysql_time_from_str(THD *thd, String *str, timestamp_type warn_type,
                              const char *warn_name, MYSQL_TIME *l_time);
 
+
+class Comp_creator
+{
+public:
+  Comp_creator() {}                           /* Remove gcc warning */
+  virtual ~Comp_creator() {}                  /* Remove gcc warning */
+  /**
+    Create operation with given arguments.
+  */
+  virtual Item_bool_rowready_func2* create(MEM_ROOT *, Item *a, Item *b)
+                                           const = 0;
+  /**
+    Create operation with given arguments in swap order.
+  */
+  virtual Item_bool_rowready_func2* create_swap(MEM_ROOT *, Item *a, Item *b)
+                                                const = 0;
+  virtual const char* symbol(bool invert) const = 0;
+  virtual bool eqne_op() const = 0;
+  virtual bool l_op() const = 0;
+};
+
+class Eq_creator :public Comp_creator
+{
+public:
+  Eq_creator() {}                             /* Remove gcc warning */
+  virtual ~Eq_creator() {}                    /* Remove gcc warning */
+  Item_bool_rowready_func2* create(MEM_ROOT *root, Item *a, Item *b) const
+  {
+    return new(root) Item_func_eq(a, b);
+  }
+  Item_bool_rowready_func2* create_swap(MEM_ROOT *root, Item *a, Item *b) const
+  {
+    return new(root) Item_func_eq(b, a);
+  }
+  const char* symbol(bool invert) const { return invert? "<>" : "="; }
+  bool eqne_op() const { return 1; }
+  bool l_op() const { return 0; }
+};
+
+class Ne_creator :public Comp_creator
+{
+public:
+  Ne_creator() {}                             /* Remove gcc warning */
+  virtual ~Ne_creator() {}                    /* Remove gcc warning */
+  Item_bool_rowready_func2* create(MEM_ROOT *root, Item *a, Item *b) const
+  {
+    return new(root) Item_func_ne(a, b);
+  }
+  Item_bool_rowready_func2* create_swap(MEM_ROOT *root, Item *a, Item *b) const
+  {
+    return new(root) Item_func_ne(b, a);
+  }
+  const char* symbol(bool invert) const { return invert? "=" : "<>"; }
+  bool eqne_op() const { return 1; }
+  bool l_op() const { return 0; }
+};
+
+class Gt_creator :public Comp_creator
+{
+public:
+  Gt_creator() {}                             /* Remove gcc warning */
+  virtual ~Gt_creator() {}                    /* Remove gcc warning */
+  Item_bool_rowready_func2* create(MEM_ROOT *root, Item *a, Item *b) const
+  {
+    return new(root) Item_func_gt(a, b);
+  }
+  Item_bool_rowready_func2* create_swap(MEM_ROOT *root, Item *a, Item *b) const
+  {
+    return new(root) Item_func_lt(b, a);
+  }
+  const char* symbol(bool invert) const { return invert? "<=" : ">"; }
+  bool eqne_op() const { return 0; }
+  bool l_op() const { return 0; }
+};
+
+class Lt_creator :public Comp_creator
+{
+public:
+  Lt_creator() {}                             /* Remove gcc warning */
+  virtual ~Lt_creator() {}                    /* Remove gcc warning */
+  Item_bool_rowready_func2* create(MEM_ROOT *root, Item *a, Item *b) const
+  {
+    return new(root) Item_func_lt(a, b);
+  }
+  Item_bool_rowready_func2* create_swap(MEM_ROOT *root, Item *a, Item *b) const
+  {
+    return new(root) Item_func_gt(b, a);
+  }
+  const char* symbol(bool invert) const { return invert? ">=" : "<"; }
+  bool eqne_op() const { return 0; }
+  bool l_op() const { return 1; }
+};
+
+class Ge_creator :public Comp_creator
+{
+public:
+  Ge_creator() {}                             /* Remove gcc warning */
+  virtual ~Ge_creator() {}                    /* Remove gcc warning */
+  Item_bool_rowready_func2* create(MEM_ROOT *root, Item *a, Item *b) const
+  {
+    return new(root) Item_func_ge(a, b);
+  }
+  Item_bool_rowready_func2* create_swap(MEM_ROOT *root, Item *a, Item *b) const
+  {
+    return new(root) Item_func_le(b, a);
+  }
+  const char* symbol(bool invert) const { return invert? "<" : ">="; }
+  bool eqne_op() const { return 0; }
+  bool l_op() const { return 0; }
+};
+
+class Le_creator :public Comp_creator
+{
+public:
+  Le_creator() {}                             /* Remove gcc warning */
+  virtual ~Le_creator() {}                    /* Remove gcc warning */
+  Item_bool_rowready_func2* create(MEM_ROOT *root, Item *a, Item *b) const
+  {
+    return new(root) Item_func_le(a, b);
+  }
+  Item_bool_rowready_func2* create_swap(MEM_ROOT *root, Item *a, Item *b) const
+  {
+    return new(root) Item_func_ge(b, a);
+  }
+  const char* symbol(bool invert) const { return invert? ">" : "<="; }
+  bool eqne_op() const { return 0; }
+  bool l_op() const { return 1; }
+};
+
 /*
   These need definitions from this file but the variables are defined
   in mysqld.h. The variables really belong in this component, but for

sql/item_subselect.cc

@@ -1779,7 +1779,7 @@ Item_in_subselect::single_value_transformer(JOIN *join)
       of the statement. Thus one of 'substitution' arguments
       can be broken in case of PS.
     */ 
-    substitution= func->create(thd, left_expr, where_item);
+    substitution= func->create(thd->mem_root, left_expr, where_item);
     have_to_be_excluded= 1;
     if (thd->lex->describe)
     {
@@ -1948,7 +1948,7 @@ bool Item_allany_subselect::transform_into_max_min(JOIN *join)
     The swap is needed for expressions of type 'f1 < ALL ( SELECT ....)'
     where we want to evaluate the sub query even if f1 would be null.
   */
-  subs= func->create_swap(thd, *(optimizer->get_cache()), subs);
+  subs= func->create_swap(thd->mem_root, *(optimizer->get_cache()), subs);
   thd->change_item_tree(place, subs);
   if (subs->fix_fields(thd, &subs))
     DBUG_RETURN(true);
@@ -2040,7 +2040,7 @@ Item_in_subselect::create_single_in_to_exists_cond(JOIN * join,
   if (join_having || select_lex->with_sum_func ||
       select_lex->group_list.elements)
   {
-    Item *item= func->create(thd, expr,
+    Item *item= func->create(thd->mem_root, expr,
                              new (thd->mem_root) Item_ref_null_helper(
                                                       &select_lex->context,
                                                       this,
@@ -2072,7 +2072,7 @@ Item_in_subselect::create_single_in_to_exists_cond(JOIN * join,
       Item *having= item;
       Item *orig_item= item;
        
-      item= func->create(thd, expr, item);
+      item= func->create(thd->mem_root, expr, item);
       if (!abort_on_null && orig_item->maybe_null)
       {
 	having= new (thd->mem_root) Item_is_not_null_test(this, having);
@@ -2116,7 +2116,7 @@ Item_in_subselect::create_single_in_to_exists_cond(JOIN * join,
       if (select_lex->master_unit()->is_union())
       {
         Item *new_having=
-          func->create(thd, expr,
+          func->create(thd->mem_root, expr,
                        new (thd->mem_root) Item_ref_null_helper(
                                                   &select_lex->context,
                                                   this,

sql/sql_yacc.yy

@@ -8797,7 +8797,7 @@ bool_pri:
           }
         | bool_pri comp_op predicate %prec EQ
           {
-            $$= (*$2)(0)->create(thd, $1, $3);
+            $$= (*$2)(0)->create(thd->mem_root, $1, $3);
             if ($$ == NULL)
               MYSQL_YYABORT;
           }