merge 5.1 => 5.5

sql/item_cmpfunc.cc

@@ -3156,6 +3156,15 @@ void Item_func_case::fix_length_and_dec()
           return;
       }
     }
+    /*
+      Set cmp_context of all WHEN arguments. This prevents
+      Item_field::equal_fields_propagator() from transforming a
+      zerofill argument into a string constant. Such a change would
+      require rebuilding cmp_items.
+    */
+    for (i= 0; i < ncases; i+= 2)
+      args[i]->cmp_context= item_cmp_type(left_result_type,
+                                          args[i]->result_type());
   }
 
   if (else_expr_num == -1 || args[else_expr_num]->maybe_null)
@@ -4143,6 +4152,16 @@ void Item_func_in::fix_length_and_dec()
       }
     }
   }
+  /*
+    Set cmp_context of all arguments. This prevents
+    Item_field::equal_fields_propagator() from transforming a zerofill integer
+    argument into a string constant. Such a change would require rebuilding
+    cmp_itmes.
+   */
+  for (arg= args + 1, arg_end= args + arg_count; arg != arg_end ; arg++)
+  {
+    arg[0]->cmp_context= item_cmp_type(left_result_type, arg[0]->result_type());
+  }
   max_length= 1;
 }