Fixed bug #21698: erroneously a field could be replaced by an

equal constant under any circumstances.
In fact this substitution can be allowed if the field is
not of a type string or if the field reference serves as 
an argument of a comparison predicate.  


mysql-test/r/func_str.result:
  Added test cases for bug #21698.
mysql-test/r/heap_hash.result:
  Adjusted results after the fix for bug #21198.
mysql-test/t/func_str.test:
  Added test cases for bug #21698.
sql/item.cc:
  Fixed bug #21198.
  Added a method to check whether a field reference can be 
  substituted for a constant equal to the field.
  This substitution is allowed if the field is not of a type string
  or if the field reference serves as an argument of a comparison
  predicate.
sql/item.h:
  Fixed bug #21698.
  Added a new virtual transformation method for a item 'compile'
  with two callback function parameters.
  Added a new virtual method 'subst_argument_checker' to be used
  as an amnalyzer method.
  This method is supposed to set its in/out argument to NULL for
  the nodes where substitution of a string field for a constant
  is not valid.
sql/item_cmpfunc.cc:
  Fixed bug #21698.
  Added an implementation of the compile method for class Item_cond.
  First it processes the Item_cond node with a callback function and if
  the latter returns TRUE it proceeds with a transformation performed by
  another callback function.
sql/item_cmpfunc.h:
  Fixed bug #21698.
  Added the implementations of 'subst_argument_checker'
  for the Item_func and Item_cond classes.
  This method is supposed to set its in/out argument to NULL for
  the nodes where substitution of a string field for a constant
  is not valid.
  Added the declaration of an implementation of the compile method for 
  class Item_cond.
  First it processes the Item_cond node with a callback function and if
  the latter returns TRUE it proceeds with a transformation performed by
  another callback function.
sql/item_func.cc:
  Fixed bug #21698.
  Added an implementation of the compile method for class Item_func.
  First it processes the Item_func node with a callback function and if
  the latter returns TRUE it proceeds with a transformation performed by
  another callback function.
sql/item_func.h:
  Fixed bug #21698.
  Added the declaration of the implementation of the compile method for
  class Item_func.
  First it processes the Item_func node with a callback function and if
  the latter returns TRUE it proceeds with a transformation performed by
  another callback function.
sql/sql_select.cc:
  Fixed bug #21698.
  Limited the conditions at which a field can be substituted 
  a for an equal constant in a formula. 
  This substitution is allowed if the field is not of a type string
  or if the field reference serves as an argument of a comparison
  predicate.

1 files changed, 4 insertions, 0 deletions

diff --git a/sql/item_cmpfunc.h b/sql/item_cmpfunc.h
index 47f9f2aa98f..f2c43833bd9 100644
--- a/sql/item_cmpfunc.h
+++ b/sql/item_cmpfunc.h
@@ -240,6 +240,7 @@ public:
   }
   Item *neg_transformer(THD *thd);
   virtual Item *negated_item();
+  bool subst_argument_checker(byte **arg) { return TRUE; }
 };
 
 class Item_func_not :public Item_bool_func
@@ -1171,6 +1172,9 @@ public:
   Item *transform(Item_transformer transformer, byte *arg);
   void traverse_cond(Cond_traverser, void *arg, traverse_order order);
   void neg_arguments(THD *thd);
+  bool subst_argument_checker(byte **arg) { return TRUE; }
+  Item *compile(Item_analyzer analyzer, byte **arg_p,
+                Item_transformer transformer, byte *arg_t);
 };