CPP: Fix compilation error when using GetInstance() caused by the Boost CL.

cpp/src/base/singleton.h

@@ -31,7 +31,7 @@ class Singleton : private boost::noncopyable {
 
   static T* GetInstance() {
     boost::call_once(Init, flag);
-    return instance;
+    return instance.get();
   }
 
  private:
@@ -43,7 +43,7 @@ class Singleton : private boost::noncopyable {
   static boost::once_flag flag;
 };
 
-template <class T> boost::scoped_ptr<T> Singleton<T>::instance = NULL;
+template <class T> boost::scoped_ptr<T> Singleton<T>::instance;
 template <class T> boost::once_flag Singleton<T>::flag = BOOST_ONCE_INIT;
 
 }  // namespace phonenumbers

cpp/src/phonenumberutil.h

@@ -62,9 +62,12 @@ class PhoneNumberUtil {
   friend struct DefaultSingletonTraits<PhoneNumberUtil>;
 #else
 class PhoneNumberUtil : public Singleton<PhoneNumberUtil> {
+  friend class Singleton<PhoneNumberUtil>;
 #endif
   friend class PhoneNumberUtilTest;
  public:
+  ~PhoneNumberUtil();
+
   // INTERNATIONAL and NATIONAL formats are consistent with the definition
   // in ITU-T Recommendation E. 123. For example, the number of the Google
   // Zürich office will be written as "+41 44 668 1800" in INTERNATIONAL
@@ -533,7 +536,6 @@ class PhoneNumberUtil : public Singleton<PhoneNumberUtil> {
   scoped_ptr<map<string, PhoneMetadata> > region_to_metadata_map_;
 
   PhoneNumberUtil();
-  ~PhoneNumberUtil();
 
   // Gets all the supported regions.
   void GetSupportedRegions(set<string>* regions) const;

cpp/src/phonenumberutil_test.cc

@@ -248,6 +248,10 @@ ostream& operator<<(ostream& os, const PhoneNumber& number) {
   return os;
 }
 
+TEST_F(PhoneNumberUtilTest, GetInstance) {
+  EXPECT_FALSE(PhoneNumberUtil::GetInstance() == NULL);
+}
+
 TEST_F(PhoneNumberUtilTest, GetSupportedRegions) {
   set<string> regions;