Bug#52120 create view cause Assertion failed: 0, file .\item_subselect.cc, line 817

We should disable const subselect item evaluation because
subselect transformation does not happen in view_prepare_mode
and thus val_...() methods can not be called.


mysql-test/r/ctype_ucs.result:
  test case
mysql-test/r/view.result:
  test case
mysql-test/t/ctype_ucs.test:
  test case
mysql-test/t/view.test:
  test case
sql/item.cc:
  disabled const subselect item evaluation in
  view prepare mode.
sql/item_subselect.cc:
  added Item_subselect::safe_charset_converter which
  prevents const item evaluation in view prepare mode.
sql/item_subselect.h:
  added Item_subselect::safe_charset_converter which
  prevents const item evaluation in view prepare mode.

1 files changed, 15 insertions, 0 deletions

diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc
index f89ca2d7955..f3fcbc4db68 100644
--- a/sql/item_subselect.cc
+++ b/sql/item_subselect.cc
@@ -122,6 +122,21 @@ void Item_subselect::cleanup()
   DBUG_VOID_RETURN;
 }
 
+
+/*
+   We cannot use generic Item::safe_charset_converter() because
+   Subselect transformation does not happen in view_prepare_mode
+   and thus we can not evaluate val_...() for const items.
+*/
+
+Item *Item_subselect::safe_charset_converter(CHARSET_INFO *tocs)
+{
+  Item_func_conv_charset *conv=
+    new Item_func_conv_charset(this, tocs, thd->lex->view_prepare_mode ? 0 : 1);
+  return conv->safe ? conv : NULL;
+}
+
+
 void Item_singlerow_subselect::cleanup()
 {
   DBUG_ENTER("Item_singlerow_subselect::cleanup");