bug #20835 (Subqueries: literal string with =any fails)

We create Item_cache_* object for each operand for each left operand of
a subquery predicate. We also create Item_func_conv_charset for each string
constant that needs charset conversion. So here we have Item_cache wrapped
into Item_func_conv_charset.
When Item_func_conv_charset wraps an constant Item it gets it's value
in constructor. The problem is that Item_cache is ready to be used only
at execution time, which is too late.
The fix makes Item_cache wrapping constant to get ready at fix_fields() time.


mysql-test/r/subselect.result:
  test result
mysql-test/t/subselect.test:
  test case
sql/item_cmpfunc.cc:
  now Item_optimizer::fix_left will store constant arguments in cache
  on fix_fields() stage

1 files changed, 2 insertions, 1 deletions

diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index 02e94d31f02..8d4b58f05a1 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -797,7 +797,8 @@ bool Item_in_optimizer::fix_left(THD *thd, Item **ref)
   }
   not_null_tables_cache= args[0]->not_null_tables();
   with_sum_func= args[0]->with_sum_func;
-  const_item_cache= args[0]->const_item();
+  if ((const_item_cache= args[0]->const_item()))
+    cache->store(args[0]);
   return 0;
 }