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, 55 insertions, 6 deletions

diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index dbf380232c4..fa01ae65b0d 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -2747,16 +2747,16 @@ bool Item_cond::walk(Item_processor processor, byte *arg)
    
   SYNOPSIS
     transform()
-    transformer   the transformer callback function to be applied to the nodes
-                  of the tree of the object
-    arg           parameter to be passed to the transformer
+      transformer   the transformer callback function to be applied to the nodes
+                    of the tree of the object
+      arg           parameter to be passed to the transformer
   
   DESCRIPTION
-    The function recursively applies the transform method with the
-    same transformer to each member item of the condition list.
+    The function recursively applies the transform method to each
+     member item of the condition list.
     If the call of the method for a member item returns a new item
     the old item is substituted for a new one.
-    After this the transform method is applied to the root node
+    After this the transformer is applied to the root node
     of the Item_cond object. 
      
   RETURN VALUES
@@ -2778,6 +2778,55 @@ Item *Item_cond::transform(Item_transformer transformer, byte *arg)
   return Item_func::transform(transformer, arg);
 }
 
+
+/*
+  Compile Item_cond object with a processor and a transformer callback functions
+   
+  SYNOPSIS
+    compile()
+      analyzer      the analyzer callback function to be applied to the nodes
+                    of the tree of the object
+      arg_p         in/out parameter to be passed to the analyzer
+      transformer   the transformer callback function to be applied to the nodes
+                    of the tree of the object
+      arg_t         parameter to be passed to the transformer
+  
+  DESCRIPTION
+    First the function applies the analyzer to the root node of
+    the Item_func object. Then if the analyzer succeeeds (returns TRUE)
+    the function recursively applies the compile method to member
+    item of the condition list.
+    If the call of the method for a member item returns a new item
+    the old item is substituted for a new one.
+    After this the transformer is applied to the root node
+    of the Item_cond object. 
+     
+  RETURN VALUES
+    Item returned as the result of transformation of the root node 
+*/
+
+Item *Item_cond::compile(Item_analyzer analyzer, byte **arg_p,
+                         Item_transformer transformer, byte *arg_t)
+{
+  if (!(this->*analyzer)(arg_p))
+    return 0;
+  
+  byte *arg_v= *arg_p;
+  List_iterator<Item> li(list);
+  Item *item;
+  while ((item= li++))
+  {
+    /* 
+      The same parameter value of arg_p must be passed
+      to analyze any argument of the condition formula.
+    */   
+    Item *new_item= item->compile(analyzer, &arg_v, transformer, arg_t);
+    if (new_item && new_item != item)
+      li.replace(new_item);
+  }
+  return Item_func::transform(transformer, arg_t);
+}
+
 void Item_cond::traverse_cond(Cond_traverser traverser,
                               void *arg, traverse_order order)
 {