Bug#37601 Cast Is Not Done On Row Comparison

In case of ROW item each compared pair does not
check if argumet collations can be aggregated and
thus appropiriate item conversion does not happen.
The fix is to add the check and convertion for ROW
pairs.


mysql-test/r/row.result:
  test result
mysql-test/t/row.test:
  test case
sql/item.cc:
  added agg_item_set_converter() function which was a part of
  agg_item_charsets() func. The only difference is that
  agg_item_set_converter() checks and converts items 
  using already known collation.
sql/item.h:
  added agg_item_set_converter() function
sql/item_cmpfunc.cc:
  In case of ROW item each compared pair does not
  check if argumet collations can be aggregated and
  thus appropiriate item conversion does not happen.
  The fix is to add the check and convertion for ROW
  pairs.

1 files changed, 2 insertions, 0 deletions

diff --git a/sql/item.h b/sql/item.h
index 1058cc5dbb8..852b0fcc1ba 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -1169,6 +1169,8 @@ bool agg_item_collations(DTCollation &c, const char *name,
                          Item **items, uint nitems, uint flags, int item_sep);
 bool agg_item_collations_for_comparison(DTCollation &c, const char *name,
                                         Item **items, uint nitems, uint flags);
+bool agg_item_set_converter(DTCollation &coll, const char *fname,
+                            Item **args, uint nargs, uint flags, int item_sep);
 bool agg_item_charsets(DTCollation &c, const char *name,
                        Item **items, uint nitems, uint flags, int item_sep);