Added tests for move conversion between optional<T> and optional<U>

include/boost/optional/optional.hpp

@@ -587,6 +587,20 @@ class optional_base : public optional_tag
     // For VC<=70 compilers this workaround dosen't work becasue the comnpiler issues and error
     // instead of choosing the wrong overload
     //
+#ifndef  BOOST_NO_CXX11_RVALUE_REFERENCES
+    // Notice that 'Expr' will be optional<T> or optional<U> (but not optional_base<..>)
+    template<class Expr>
+    void construct ( Expr&& expr, optional_tag const* )
+     {
+       if ( expr.is_initialized() )
+       {
+         // An exception can be thrown here.
+         // It it happens, THIS will be left uninitialized.
+         new (m_storage.address()) internal_type(types::move(expr.get())) ;
+         m_initialized = true ;
+       }
+     }
+#else
     // Notice that 'Expr' will be optional<T> or optional<U> (but not optional_base<..>)
     template<class Expr>
     void construct ( Expr const& expr, optional_tag const* )
@@ -600,6 +614,7 @@ class optional_base : public optional_tag
        }
      }
 #endif
+#endif // defined BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION
 
     void assign_value ( argument_type val, is_not_reference_tag ) { get_impl() = val; }
     void assign_value ( argument_type val, is_reference_tag     ) { construct(val); }
@@ -814,7 +829,7 @@ class optional : public optional_detail::optional_base<T>
 #endif // !defined  BOOST_NO_CXX11_RVALUE_REFERENCES
 #endif // !defined(BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT) && !defined(BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION)
 
-    // Assigns from another convertible optional<U> (converts && deep-copies the rhs value)
+    // Copy-assigns from another convertible optional<U> (converts && deep-copies the rhs value)
     // Requires a valid conversion from U to T.
     // Basic Guarantee: If T::T( U const& ) throws, this is left UNINITIALIZED
     template<class U>
@@ -823,6 +838,18 @@ class optional : public optional_detail::optional_base<T>
         this->assign(rhs);
         return *this ;
       }
+      
+#ifndef  BOOST_NO_CXX11_RVALUE_REFERENCES
+    // Move-assigns from another convertible optional<U> (converts && deep-moves the rhs value)
+    // Requires a valid conversion from U to T.
+    // Basic Guarantee: If T::T( U && ) throws, this is left UNINITIALIZED
+    template<class U>
+    optional& operator= ( optional<U> && rhs )
+      {
+        this->assign(boost::move(rhs));
+        return *this ;
+      }
+#endif
 
     // Assigns from another optional<T> (deep-copies the rhs value)
     // Basic Guarantee: If T::T( T const& ) throws, this is left UNINITIALIZED

test/optional_test_move.cpp

@@ -239,6 +239,8 @@ public:
 private:
   MoveOnly(MoveOnly const&);
   void operator=(MoveOnly const&);
+  
+  friend class MoveOnlyB;
 };
 
 void test_with_move_only()
@@ -262,6 +264,56 @@ void test_with_move_only()
     BOOST_CHECK(o4->val == 0);
 }
 
+class MoveOnlyB
+{
+public:
+  int val;
+  MoveOnlyB(int v) : val(v) {}
+  MoveOnlyB(MoveOnlyB&& rhs) : val(rhs.val) { rhs.val = 0; }
+  void operator=(MoveOnlyB&& rhs) {val = rhs.val; rhs.val = 0; }
+  MoveOnlyB(MoveOnly&& rhs) : val(rhs.val) { rhs.val = 0; }
+  void operator=(MoveOnly&& rhs) {val = rhs.val; rhs.val = 0; }
+  
+private:
+  MoveOnlyB(MoveOnlyB const&);
+  void operator=(MoveOnlyB const&);
+  MoveOnlyB(MoveOnly const&);
+  void operator=(MoveOnly const&);
+};
+
+void test_move_assign_from_optional_U()
+{
+    optional<MoveOnly> a((MoveOnly(2)));
+    optional<MoveOnlyB> b1;
+    b1 = boost::move(a);
+    
+    BOOST_CHECK(b1);
+    BOOST_CHECK(b1->val == 2);
+    BOOST_CHECK(a);
+    BOOST_CHECK(a->val == 0);
+    
+    b1 = MoveOnly(4);
+    
+    BOOST_CHECK(b1);
+    BOOST_CHECK(b1->val == 4);
+}
+
+void test_move_ctor_from_optional_U()
+{
+    optional<MoveOnly> a((MoveOnly(2)));
+    optional<MoveOnlyB> b1(boost::move(a));
+    
+    BOOST_CHECK(b1);
+    BOOST_CHECK(b1->val == 2);
+    BOOST_CHECK(a);
+    BOOST_CHECK(a->val == 0);
+    
+    optional<MoveOnlyB> b2(( optional<MoveOnly>(( MoveOnly(4) )) ));
+    
+    BOOST_CHECK(b2);
+    BOOST_CHECK(b2->val == 4);
+}
+
 // these 4 classes have different noexcept signatures in move operations
 struct NothrowBoth {
   NothrowBoth(NothrowBoth&&) BOOST_NOEXCEPT_IF(true) {};
@@ -312,9 +364,11 @@ int test_main( int, char* [] )
     test_move_ctor_from_U();
     test_move_ctor_form_T();
     test_move_ctor_from_optional_T();
+    test_move_ctor_from_optional_U();
     test_move_assign_from_U();
     test_move_assign_from_T();
     test_move_assign_from_optional_T();
+    test_move_assign_from_optional_U();
     test_with_move_only();
 #endif
   }