Bug #21531: EXPORT_SET() doesn't accept args with coercible character sets

- Fix typo in Item_func_export_set::fix_length_and_dec() which caused character set aggregation to fail
- Remove default argument from last arg of agg_arg_charsets() function, to reduce potential errors


mysql-test/r/func_misc.result:
  Test EXPORT_SET() with charset coersion (bug #21531)
mysql-test/t/func_misc.test:
  Test EXPORT_SET() with charset coersion (bug #21531)
sql/item_func.h:
  Remove default argument from last arg of agg_arg_charsets() function, to reduce potential errors.
sql/item_strfunc.cc:
  Fix typo in Item_func_export_set::fix_length_and_dec() which caused character set aggregation to fail.

2 files changed, 3 insertions, 4 deletions

diff --git a/sql/item_func.h b/sql/item_func.h
index 51f9d3fb36f..aaf74e4f7af 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -156,8 +156,7 @@ public:
     return agg_item_collations_for_comparison(c, func_name(),
                                               items, nitems, flags);
   }
-  bool agg_arg_charsets(DTCollation &c, Item **items, uint nitems,
-                        uint flags= 0)
+  bool agg_arg_charsets(DTCollation &c, Item **items, uint nitems, uint flags)
   {
     return agg_item_charsets(c, func_name(), items, nitems, flags);
   }
diff --git a/sql/item_strfunc.cc b/sql/item_strfunc.cc
index 56a31d074ac..a43f8b5a22a 100644
--- a/sql/item_strfunc.cc
+++ b/sql/item_strfunc.cc
@@ -2624,8 +2624,8 @@ void Item_func_export_set::fix_length_and_dec()
   uint sep_length=(arg_count > 3 ? args[3]->max_length : 1);
   max_length=length*64+sep_length*63;
 
-  if (agg_arg_charsets(collation, args+1, min(4,arg_count)-1),
-                       MY_COLL_ALLOW_CONV)
+  if (agg_arg_charsets(collation, args+1, min(4,arg_count)-1,
+                       MY_COLL_ALLOW_CONV))
     return;
 }