Bug#27589205 CALL TO FUNCTION COMPARE_FIELDS_BY_TABLE_ORDER

Use void* for function arguments, and cast Item_field* in function body.

compare_fields_by_table_order(Item_field*, Item_field*, void*) through
pointer to incorrect function type 'int (*)(void *, void *, void *)'
sql/sql_optimizer.cc:3904: note: compare_fields_by_table_order(Item_field*,
Item_field*, void*) defined here
    #0 0x34ac57d in base_list::sort(int (*)(void*, void*, void*), void*)
sql/sql_list.h:278:13
    #1 0x49ad303 in substitute_for_best_equal_field(Item*, COND_EQUAL*,

Change-Id: I4f5417304a24201682f32fc7631034de7aa62589

Author: Tor Didriksen

sql/item_cmpfunc.cc

@@ -5842,8 +5842,8 @@ bool Item_equal::merge(THD *thd, Item_equal *item) {
   @param arg          context extra parameter for the cmp function
 */
 
-void Item_equal::sort(Item_field_cmpfunc compare, void *arg) {
-  fields.sort((Node_cmp_func)compare, arg);
+void Item_equal::sort(Node_cmp_func compare, void *arg) {
+  fields.sort(compare, arg);
 }
 
 /**

sql/item_cmpfunc.h

@@ -67,8 +67,6 @@ struct MY_BITMAP;
 
 typedef int (Arg_comparator::*arg_cmp_func)();
 
-typedef int (*Item_field_cmpfunc)(Item_field *f1, Item_field *f2, void *arg);
-
 class Arg_comparator {
   Item **a, **b;
   arg_cmp_func func;
@@ -2039,7 +2037,7 @@ class Item_equal final : public Item_bool_func {
   longlong val_int() override;
   const char *func_name() const override { return "multiple equal"; }
   optimize_type select_optimize() const override { return OPTIMIZE_EQUAL; }
-  void sort(Item_field_cmpfunc compare, void *arg);
+  void sort(Node_cmp_func compare, void *arg);
   friend class Item_equal_iterator;
   bool resolve_type(THD *) override;
   bool fix_fields(THD *thd, Item **ref) override;

sql/sql_optimizer.cc

@@ -3890,8 +3890,8 @@ bool build_equal_items(THD *thd, Item *cond, Item **retcond,
     The function finds out what of two fields is better according
     this criteria.
 
-  @param field1          first field item to compare
-  @param field2          second field item to compare
+  @param v_field1        first field item to compare
+  @param v_field2        second field item to compare
   @param table_join_idx  index to tables determining table order
 
   @retval
@@ -3902,8 +3902,10 @@ bool build_equal_items(THD *thd, Item *cond, Item **retcond,
     0  otherwise
 */
 
-static int compare_fields_by_table_order(Item_field *field1, Item_field *field2,
+static int compare_fields_by_table_order(void *v_field1, void *v_field2,
                                          void *table_join_idx) {
+  Item_field *field1 = static_cast<Item_field *>(v_field1);
+  Item_field *field2 = static_cast<Item_field *>(v_field2);
   int cmp = 0;
   bool outer_ref = 0;
   if (field1->used_tables() & OUTER_REF_TABLE_BIT) {