diff --git a/compiler/cpp/src/audit/readme.txt b/compiler/cpp/src/audit/readme.txt
new file mode 100644
index 0000000..f1c53e3
--- /dev/null
+++ b/compiler/cpp/src/audit/readme.txt
@@ -0,0 +1,32 @@
+Typical usage:
+    thrift.exe --audit <oldFile> <newFile>
+Example run:
+    > thrift.exe --audit test.thrift break1.thrift
+    [Thrift Audit Failure:break1.thrift] New Thrift File has missing function base_function3
+    [Thrift Audit Warning:break1.thrift] Constant const3 has different value
+
+Problems that the audit tool can catch:
+Errors
+    Removing an enum value
+    Changing the type of a struct field
+    Changing the required-ness of a struct field
+    Removing a struct field
+    Adding a required struct field
+    Adding a struct field 'in the middle'.  This usually indicates an old ID has been recycled
+    Struct removed
+    Oneway-ness change
+    Return type change
+    Missing function
+    Missing service
+    Change in service inheritance
+Warnings
+    Removing a language namespace declaration
+    Changing a namespace
+    Changing an enum value's name
+    Removing an enum class
+    Default value changed
+    Struct field name change
+    Removed constant
+    Type of constant changed
+    Value of constant changed
+    
\ No newline at end of file
diff --git a/compiler/cpp/src/audit/t_audit.cpp b/compiler/cpp/src/audit/t_audit.cpp
new file mode 100644
index 0000000..afcbd5e
--- /dev/null
+++ b/compiler/cpp/src/audit/t_audit.cpp
@@ -0,0 +1,466 @@
+
+#include <cassert>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <time.h>
+#include <string>
+#include <algorithm>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <limits.h>
+
+// Careful: must include globals first for extern definitions
+#include "globals.h"
+
+#include "parse/t_program.h"
+#include "parse/t_scope.h"
+#include "parse/t_const.h"
+#include "parse/t_field.h"
+
+#include "version.h"
+
+#include "t_audit.h"
+
+extern int g_warn;
+extern std::string g_curpath;
+extern bool g_return_failure;
+
+void thrift_audit_warning(int level, const char* fmt, ...) {
+   if (g_warn < level) {
+      return;
+   }
+   va_list args;
+   printf("[Thrift Audit Warning:%s] ", g_curpath.c_str());
+   va_start(args, fmt);
+   vprintf(fmt, args);
+   va_end(args);
+   printf("\n");
+}
+
+void thrift_audit_failure(const char* fmt, ...) {
+  va_list args;
+  fprintf(stderr, "[Thrift Audit Failure:%s] ", g_curpath.c_str());
+  va_start(args, fmt);
+  vfprintf(stderr, fmt, args);
+  va_end(args);
+  fprintf(stderr, "\n");
+  g_return_failure = true;
+}
+
+void compare_namespace(t_program* newProgram, t_program* oldProgram)
+{
+   const std::map<std::string, std::string>& newNamespaceMap = newProgram->get_all_namespaces();
+   const std::map<std::string, std::string>& oldNamespaceMap = oldProgram->get_all_namespaces();
+
+   for(std::map<std::string, std::string>::const_iterator oldNamespaceMapIt = oldNamespaceMap.begin();
+         oldNamespaceMapIt != oldNamespaceMap.end();
+         oldNamespaceMapIt++)
+   {
+      std::map<std::string, std::string>::const_iterator newNamespaceMapIt = newNamespaceMap.find(oldNamespaceMapIt->first);
+      if(newNamespaceMapIt == newNamespaceMap.end())
+      {
+         thrift_audit_warning(1, "Language %s not found in new thrift file\n", (oldNamespaceMapIt->first).c_str());
+      }
+      else if((newNamespaceMapIt->second) != oldNamespaceMapIt->second)
+      {
+         thrift_audit_warning(1, "Namespace %s changed in new thrift file\n", (oldNamespaceMapIt->second).c_str());
+      }
+   }
+}
+
+void compare_enum_values(t_enum* newEnum,t_enum* oldEnum)
+{
+   const std::vector<t_enum_value*>& oldEnumValues = oldEnum->get_constants();
+   for(std::vector<t_enum_value*>::const_iterator oldEnumValuesIt = oldEnumValues.begin();
+         oldEnumValuesIt != oldEnumValues.end();
+         oldEnumValuesIt++)
+   {
+      int enumValue = (*oldEnumValuesIt)->get_value();
+      t_enum_value* newEnumValue = newEnum->get_constant_by_value(enumValue);
+      if(newEnumValue != NULL)
+      {
+         std::string enumName = (*oldEnumValuesIt)->get_name();
+         if(enumName != newEnumValue->get_name())
+         {
+            thrift_audit_warning(1, "Name of the value %d changed in enum %s\n", enumValue, oldEnum->get_name().c_str());
+         }      
+      }
+      else
+      {
+         thrift_audit_failure("Enum value %d missing in %s\n", enumValue, oldEnum->get_name().c_str());
+      }
+
+   }
+}
+
+void compare_enums(const std::vector<t_enum*>& newEnumList, const std::vector<t_enum*>& oldEnumList)
+{
+   std::map<std::string,t_enum*> newEnumMap;
+   std::vector<t_enum*>::const_iterator newEnumIt;
+   for(newEnumIt = newEnumList.begin(); newEnumIt != newEnumList.end(); newEnumIt++)
+   {
+      newEnumMap[(*newEnumIt)->get_name()] = *newEnumIt;
+   }
+   std::vector<t_enum*>::const_iterator oldEnumIt;
+   for(oldEnumIt = oldEnumList.begin(); oldEnumIt != oldEnumList.end(); oldEnumIt++)
+   {
+      std::map<std::string,t_enum*>::iterator newEnumMapIt;
+      newEnumMapIt = newEnumMap.find((*oldEnumIt)->get_name());
+
+      if(newEnumMapIt == newEnumMap.end())
+      {
+         thrift_audit_warning(1, "Enum %s not found in new thrift file\n",(*oldEnumIt)->get_name().c_str());
+      }
+      else
+      {
+         compare_enum_values(newEnumMapIt->second, *oldEnumIt);
+      }
+   }
+}
+
+//This function returns 'true' if the two arguements are of same types.
+//Returns false if they are of different type
+bool compare_type(t_type* newType, t_type* oldType)
+{
+   //Comparing names of two types will work when the newType and oldType are basic types or structs or enums.
+   //However, when they are containers, get_name() returns empty for which we have to compare the type of 
+   //their elements as well.
+   if((newType->get_name()).empty() && (oldType->get_name()).empty())
+   {
+
+      if(newType->is_list() && oldType->is_list())
+      {
+         t_type* newElementType = ((t_list*)newType)->get_elem_type();
+         t_type* oldElementType = ((t_list*)oldType)->get_elem_type();
+         return compare_type(newElementType, oldElementType);
+      }
+      else if(newType->is_map() && oldType->is_map())
+      {
+         t_type* newKeyType = ((t_map*)newType)->get_key_type();
+         t_type* oldKeyType = ((t_map*)oldType)->get_key_type();
+
+         t_type* newValType = ((t_map*)newType)->get_val_type();
+         t_type* oldValType = ((t_map*)oldType)->get_val_type();
+
+         return (compare_type(newKeyType, oldKeyType) && compare_type(newValType, oldValType));
+      }
+      else if(newType->is_set() && oldType->is_set())
+      {
+         t_type* newElementType = ((t_set*)newType)->get_elem_type();
+         t_type* oldElementType = ((t_set*)oldType)->get_elem_type();
+         return compare_type(newElementType, oldElementType); 
+      }
+      else
+      {
+         return false;
+      }
+   }
+   else if(newType->get_name() == oldType->get_name())
+   {
+      return true;
+   }
+   else
+   {
+      return false;
+   }
+}
+
+bool compare_pair(std::pair<t_const_value*, t_const_value*> newMapPair, std::pair<t_const_value*, t_const_value*> oldMapPair)
+{
+   return compare_defaults(newMapPair.first, oldMapPair.first) && compare_defaults(newMapPair.second, oldMapPair.second);
+}   
+
+// This function returns 'true' if the default values are same. Returns false if they are different.
+bool compare_defaults(t_const_value* newStructDefault, t_const_value* oldStructDefault)
+{
+   if(newStructDefault == NULL && oldStructDefault == NULL) return true;
+   else if(newStructDefault == NULL && oldStructDefault != NULL) return false;
+   else if (newStructDefault != NULL && oldStructDefault == NULL) return false;
+
+   if(newStructDefault->get_type() != oldStructDefault->get_type())
+   {
+      return false;
+   }
+
+   switch(newStructDefault->get_type())
+   {
+      case t_const_value::CV_INTEGER:
+         return (newStructDefault->get_integer() == oldStructDefault->get_integer());
+      case t_const_value::CV_DOUBLE:
+         return (newStructDefault->get_double() == oldStructDefault->get_double());
+      case t_const_value::CV_STRING:
+         return (newStructDefault->get_string() == oldStructDefault->get_string());
+      case t_const_value::CV_LIST:
+         {
+            const std::vector<t_const_value*>& oldDefaultList = oldStructDefault->get_list();
+            const std::vector<t_const_value*>& newDefaultList = newStructDefault->get_list();
+            bool defaultValuesCompare = (oldDefaultList.size() == newDefaultList.size());
+
+            return defaultValuesCompare && std::equal(newDefaultList.begin(), newDefaultList.end(), oldDefaultList.begin(), compare_defaults);
+         }
+      case t_const_value::CV_MAP:
+         {
+            const std::map<t_const_value*, t_const_value*> newMap = newStructDefault->get_map();
+            const std::map<t_const_value*, t_const_value*> oldMap = oldStructDefault->get_map();
+
+            bool defaultValuesCompare = (oldMap.size() == newMap.size());
+
+            return defaultValuesCompare && std::equal(newMap.begin(), newMap.end(), oldMap.begin(), compare_pair);
+         }
+      case t_const_value::CV_IDENTIFIER:
+         return (newStructDefault->get_identifier() == oldStructDefault->get_identifier());
+      default:
+         return false;
+   }
+
+}
+
+void compare_struct_field(t_field* newField, t_field* oldField, std::string oldStructName)
+{
+   t_type* newFieldType = newField->get_type();
+   t_type* oldFieldType = oldField->get_type();
+   if(!compare_type(newFieldType, oldFieldType))
+   {
+      thrift_audit_failure("Struct Field Type Changed for Id = %d in %s \n", newField->get_key(), oldStructName.c_str());
+   }
+
+   // A Struct member can be optional if it is mentioned explicitly, or if it is assigned with default values.
+   bool newStructFieldOptional = (newField->get_req() != t_field::T_REQUIRED);
+   bool oldStructFieldOptional = (oldField->get_req() != t_field::T_REQUIRED);
+
+   if(newStructFieldOptional != oldStructFieldOptional)
+   {
+      thrift_audit_failure("Struct Field Requiredness Changed for Id = %d in %s \n", newField->get_key(), oldStructName.c_str());
+   }
+   if(newStructFieldOptional || oldStructFieldOptional)
+   {
+      if(!compare_defaults(newField->get_value(), oldField->get_value()))
+      {
+         thrift_audit_warning(1, "Default value changed for Id = %d in %s \n", newField->get_key(), oldStructName.c_str());
+      }
+   }
+
+   std::string fieldName = newField->get_name();
+   if(fieldName != oldField->get_name())
+   {
+      thrift_audit_warning(1, "Struct field name changed for Id = %d in %s\n", newField->get_key(), oldStructName.c_str());
+   }
+
+}
+
+void compare_single_struct(t_struct* newStruct, t_struct* oldStruct, const std::string& oldStructName = std::string())
+{
+   std::string structName = oldStructName.empty() ? oldStruct->get_name() : oldStructName;
+   const std::vector<t_field*>& oldStructMembersInIdOrder = oldStruct->get_sorted_members();
+   const std::vector<t_field*>& newStructMembersInIdOrder = newStruct->get_sorted_members();
+   std::vector<t_field*>::const_iterator oldStructMemberIt = oldStructMembersInIdOrder.begin();
+   std::vector<t_field*>::const_iterator newStructMemberIt = newStructMembersInIdOrder.begin();
+
+   // Since we have the struct members in their ID order, comparing their IDs can be done by traversing the two member
+   // lists together.  
+   while(!(oldStructMemberIt == oldStructMembersInIdOrder.end() && newStructMemberIt == newStructMembersInIdOrder.end()))
+   {
+      if(newStructMemberIt == newStructMembersInIdOrder.end() && oldStructMemberIt != oldStructMembersInIdOrder.end())
+      {
+         // A field ID has been removed from the end.
+         thrift_audit_failure("Struct Field removed for Id = %d in %s \n", (*oldStructMemberIt)->get_key(), structName.c_str());
+         oldStructMemberIt++;
+      }
+      else if(newStructMemberIt != newStructMembersInIdOrder.end() && oldStructMemberIt == oldStructMembersInIdOrder.end())
+      {
+         //New field ID has been added to the end.
+         if((*newStructMemberIt)->get_req() == t_field::T_REQUIRED)
+         {
+            thrift_audit_failure("Required Struct Field Added for Id = %d in %s \n", (*newStructMemberIt)->get_key(), structName.c_str());
+         }
+         newStructMemberIt++;
+      }
+      else if((*newStructMemberIt)->get_key() == (*oldStructMemberIt)->get_key())
+      {
+         //Field ID found in both structs. Compare field types, default values.
+         compare_struct_field(*newStructMemberIt, *oldStructMemberIt, structName);
+
+         newStructMemberIt++;
+         oldStructMemberIt++;
+      }
+      else if((*newStructMemberIt)->get_key() < (*oldStructMemberIt)->get_key())
+      {
+         //New Field Id is inserted in between
+         //Adding fields to struct is fine, but adding them in the middle is suspicious. Error!!
+         thrift_audit_failure("Struct field is added in the middle with Id = %d in %s\n",  (*newStructMemberIt)->get_key(),  structName.c_str());
+         newStructMemberIt++;
+      }
+      else if((*newStructMemberIt)->get_key() > (*oldStructMemberIt)->get_key())
+      {
+         //A field is deleted in newStruct.
+         thrift_audit_failure("Struct Field removed for Id = %d in %s \n",  (*oldStructMemberIt)->get_key(), structName.c_str());
+         oldStructMemberIt++;
+      }
+
+   }
+}
+
+void compare_structs(const std::vector<t_struct*>& newStructList, const std::vector<t_struct*>& oldStructList)
+{
+   std::map<std::string,t_struct*> newStructMap;
+   std::vector<t_struct*>::const_iterator newStructListIt;
+   for(newStructListIt = newStructList.begin(); newStructListIt != newStructList.end(); newStructListIt++)
+   {
+      newStructMap[(*newStructListIt)->get_name()] = *newStructListIt;
+   }
+
+   std::vector<t_struct*>::const_iterator oldStructListIt;
+   for(oldStructListIt = oldStructList.begin(); oldStructListIt != oldStructList.end(); oldStructListIt++)
+   {
+      std::map<std::string, t_struct*>::iterator newStructMapIt;
+      newStructMapIt = newStructMap.find((*oldStructListIt)->get_name());
+      if(newStructMapIt == newStructMap.end())
+      {
+         thrift_audit_failure("Struct %s not found in new thrift file\n", (*oldStructListIt)->get_name().c_str());
+      }
+      else
+      {
+         compare_single_struct(newStructMapIt->second, *oldStructListIt);
+      }
+   }
+
+}
+
+void compare_single_function(t_function* newFunction, t_function* oldFunction)
+{
+   t_type* newFunctionReturnType = newFunction->get_returntype();
+
+   if(newFunction->is_oneway() != oldFunction->is_oneway())
+   {
+      thrift_audit_failure("Oneway attribute changed for function %s\n",oldFunction->get_name().c_str());
+   }
+   if(!compare_type(newFunctionReturnType, oldFunction->get_returntype()))
+   {
+      thrift_audit_failure("Return type changed for function %s\n",oldFunction->get_name().c_str());
+   }
+
+   //Compare function arguments.
+   compare_single_struct(newFunction->get_arglist(), oldFunction->get_arglist());
+   std::string exceptionName = oldFunction->get_name();
+   exceptionName += "_exception";
+   compare_single_struct(newFunction->get_xceptions(), oldFunction->get_xceptions(), exceptionName);
+}
+
+void compare_functions(const std::vector<t_function*>& newFunctionList, const std::vector<t_function*>& oldFunctionList)
+{
+   std::map<std::string, t_function*> newFunctionMap;
+   std::map<std::string, t_function*>::iterator newFunctionMapIt;
+   for(std::vector<t_function*>::const_iterator newFunctionIt = newFunctionList.begin();
+         newFunctionIt != newFunctionList.end();
+         newFunctionIt++)
+   {
+      newFunctionMap[(*newFunctionIt)->get_name()] = *newFunctionIt;
+   }
+
+   for(std::vector<t_function*>::const_iterator oldFunctionIt = oldFunctionList.begin();
+         oldFunctionIt != oldFunctionList.end();
+         oldFunctionIt++)
+   {
+      newFunctionMapIt = newFunctionMap.find((*oldFunctionIt)->get_name());
+      if(newFunctionMapIt == newFunctionMap.end())
+      {
+         thrift_audit_failure("New Thrift File has missing function %s\n",(*oldFunctionIt)->get_name().c_str());
+         continue;
+      }
+      else
+      {
+         //Function is found in both thrift files. Compare return type and argument list
+         compare_single_function(newFunctionMapIt->second, *oldFunctionIt);
+      }
+   }
+
+}
+
+void compare_services(const std::vector<t_service*>& newServices, const std::vector<t_service*>& oldServices)
+{
+   std::vector<t_service*>::const_iterator oldServiceIt;
+
+   std::map<std::string, t_service*> newServiceMap;
+   for(std::vector<t_service*>::const_iterator newServiceIt = newServices.begin();
+         newServiceIt != newServices.end();
+         newServiceIt++)
+   {
+      newServiceMap[(*newServiceIt)->get_name()] = *newServiceIt;
+   }
+
+
+   for(oldServiceIt = oldServices.begin(); oldServiceIt != oldServices.end(); oldServiceIt++)
+   {
+      const std::string oldServiceName = (*oldServiceIt)->get_name();
+      std::map<std::string, t_service*>::iterator newServiceMapIt = newServiceMap.find(oldServiceName);
+
+      if(newServiceMapIt == newServiceMap.end())
+      {
+         thrift_audit_failure("New Thrift file is missing a service %s\n", oldServiceName.c_str());
+      }
+      else
+      {
+         t_service* oldServiceExtends = (*oldServiceIt)->get_extends();
+         t_service* newServiceExtends = (newServiceMapIt->second)->get_extends();
+
+         if(oldServiceExtends == NULL)
+         {
+            // It is fine to add extends. So if service in older thrift did not have any extends, we are fine.
+            // DO Nothing
+         }
+         else if(oldServiceExtends != NULL && newServiceExtends == NULL)
+         {
+            thrift_audit_failure("Change in Service inheritance for %s\n", oldServiceName.c_str());
+         }
+         else
+         {
+            std::string oldExtendsName = oldServiceExtends->get_name();
+            std::string newExtendsName = newServiceExtends->get_name();
+
+            if( newExtendsName != oldExtendsName)
+            {
+               thrift_audit_failure("Change in Service inheritance for %s\n", oldServiceName.c_str());
+            }
+         }
+
+         compare_functions((newServiceMapIt->second)->get_functions(), (*oldServiceIt)->get_functions());
+      }
+
+   }
+
+}
+
+void compare_consts(const std::vector<t_const*>& newConst, const std::vector<t_const*>& oldConst)
+{
+   std::vector<t_const*>::const_iterator newConstIt;
+   std::vector<t_const*>::const_iterator oldConstIt;
+
+   std::map<std::string, t_const*> newConstMap;
+
+   for(newConstIt = newConst.begin(); newConstIt != newConst.end(); newConstIt++)
+   {
+      newConstMap[(*newConstIt)->get_name()] = *newConstIt;
+   }
+
+   std::map<std::string, t_const*>::const_iterator newConstMapIt;
+   for(oldConstIt = oldConst.begin(); oldConstIt != oldConst.end(); oldConstIt++)
+   {
+      newConstMapIt = newConstMap.find((*oldConstIt)->get_name());
+      if(newConstMapIt == newConstMap.end())
+      {
+         thrift_audit_warning(1, "Constants Missing %s \n", ((*oldConstIt)->get_name()).c_str());
+      }
+      else if(!compare_type((newConstMapIt->second)->get_type(), (*oldConstIt)->get_type()))
+      {
+         thrift_audit_warning(1, "Constant %s is of different type \n", ((*oldConstIt)->get_name()).c_str());
+      }
+      else if(!compare_defaults((newConstMapIt->second)->get_value(), (*oldConstIt)->get_value()))
+      {
+         thrift_audit_warning(1, "Constant %s has different value\n", ((*oldConstIt)->get_name()).c_str());
+      }
+   }
+}
+
+
diff --git a/compiler/cpp/src/audit/t_audit.h b/compiler/cpp/src/audit/t_audit.h
new file mode 100644
index 0000000..fd0013a
--- /dev/null
+++ b/compiler/cpp/src/audit/t_audit.h
@@ -0,0 +1,11 @@
+#ifndef T_AUDIT_H
+#define T_AUDIT_H
+
+void compare_namespace(t_program* newProgram, t_program* oldProgram);
+void compare_enums(const std::vector<t_enum*>& newEnumList, const std::vector<t_enum*>& oldEnumList);
+bool compare_defaults(t_const_value* newStructDefault, t_const_value* oldStructDefault);
+void compare_structs(const std::vector<t_struct*>& newStructList, const std::vector<t_struct*>& oldStructList);
+void compare_services(const std::vector<t_service*>& newServices, const std::vector<t_service*>& oldServices);
+void compare_consts(const std::vector<t_const*>& newConst, const std::vector<t_const*>& oldConst);
+
+#endif