MDEV-26732 Assertion `0' failed in Item::val_nativebb-10.5-bar-MDEV-26732

Also fixes MDEV-24619 Wrong result or Assertion `0' in Item::val_native / Type_handler_inet6::Item_val_native_with_conversion

Type_handler_inet6::create_item_copy() created a generic Item_copy_string,
which does not implement val_native() - it has a dummy implementation
with DBUG_ASSERT(0), which made the server crash.

Fix:

- Adding a new class Type_handler_inet6
  which implements val_native().
- Fixing Type_handler_inet6::create_item_copy()
  to make Item_copy_inet6 instead of Item_copy_string.

1 files changed, 57 insertions, 0 deletions

diff --git a/plugin/type_inet/sql_type_inet.cc b/plugin/type_inet/sql_type_inet.cc
index 14d854be14f..9832a84a1b9 100644
--- a/plugin/type_inet/sql_type_inet.cc
+++ b/plugin/type_inet/sql_type_inet.cc
@@ -1227,6 +1227,57 @@ public:
 };
 
 
+class Item_copy_inet6: public Item_copy
+{
+  NativeBufferInet6 m_value;
+public:
+  Item_copy_inet6(THD *thd, Item *item_arg): Item_copy(thd, item_arg) {}
+
+  bool val_native(THD *thd, Native *to) override
+  {
+    if (null_value)
+      return true;
+    return to->copy(m_value.ptr(), m_value.length());
+  }
+  String *val_str(String *to) override
+  {
+    if (null_value)
+      return NULL;
+    Inet6_null tmp(m_value.ptr(), m_value.length());
+    return tmp.is_null() || tmp.to_string(to) ? NULL : to;
+  }
+  my_decimal *val_decimal(my_decimal *to) override
+  {
+    my_decimal_set_zero(to);
+    return to;
+  }
+  double val_real() override
+  {
+    return 0;
+  }
+  longlong val_int() override
+  {
+    return 0;
+  }
+  bool get_date(THD *thd, MYSQL_TIME *ltime, date_mode_t fuzzydate) override
+  {
+    set_zero_time(ltime, MYSQL_TIMESTAMP_TIME);
+    return null_value;
+  }
+  void copy() override
+  {
+    null_value= item->val_native(current_thd, &m_value);
+    DBUG_ASSERT(null_value == item->null_value);
+  }
+  int save_in_field(Field *field, bool no_conversions) override
+  {
+    return Item::save_in_field(field, no_conversions);
+  }
+  Item *get_copy(THD *thd) override
+  { return get_item_copy<Item_copy_inet6>(thd, this); }
+};
+
+
 class in_inet6 :public in_vector
 {
   Inet6 m_value;
@@ -1465,6 +1516,12 @@ Item_cache *Type_handler_inet6::Item_get_cache(THD *thd, const Item *item) const
 }
 
 
+Item_copy *Type_handler_inet6::create_item_copy(THD *thd, Item *item) const
+{
+  return new (thd->mem_root) Item_copy_inet6(thd, item);
+}
+
+
 Item *
 Type_handler_inet6::make_const_item_for_comparison(THD *thd,
                                                    Item *src,