c++ - Can std::function be move-constructed from rvalue reference to a temporary functor object? -

i have untemplated functor object i'm trying store std::function inside object. object heavyweight, it's marked uncopyable, have move constructor. however, trying construct std::function, or assign it, temporary constructor fails.

here minimal example provoke error.

// pretend heavyweight functor can't copied. struct exampletest {     int x;     int operator()(void) const {return x*2;}     exampletest(  ) :x(0){}     exampletest( int ) :x(a){}      // allow move     exampletest( exampletest &&other ) :x(other.x) {};  private: // disallow copy, assignment     exampletest( const exampletest &other );     void operator=( const exampletest &other ); };  // stores big functors , other times stores tiny lambdas. struct examplecontainer {     examplecontainer( int );     std::function<int(void)> funct; };  /******** error:  compiler error: 'exampletest::exampletest' : cannot access private member   declared in class 'exampletest' ******************/ examplecontainer::examplecontainer( int x )     : funct( exampletest( x ) )  {}  /******** error:  compiler error: 'exampletest::exampletest' : cannot access private member   declared in class 'exampletest' ******************/ int setexample( examplecontainer *container ) {     container->funct = exampletest();     return container->funct(); } 

in simpler construction, i'm making local function, error:

int contrivedexample(  ) {     // parens sidestep vexing parse      std::function<int()> zug( (exampletest()) );     /*** error: 'exampletest::exampletest' : cannot access private member          declared in class 'exampletest' */     int troz = zug(  ) ;     return troz; } 

so far can tell, in of these cases, temporary exampletest ought passed function constructor rvalue. yet compiler wants copy them.

what gives? possible pass uncopyable (but move-copyable) functor objects std::function constructor? there workarounds pointers , on, want understand going on here.

the specific errors above visual studio 2012 ctp c++11 patch. gcc 4.8 , clang 3 fall down, own error messages.

this object heavyweight, it's marked uncopyable, have move constructor.

if functor non-copyable, not meet necessary requirements being used std::function. paragraph 20.8.11.2.1/7 of c++11 standard specifies:

template<class f> function(f f); template <class f, class a> function(allocator_arg_t, const a& a, f f); 

7 requires: f shall copyconstructible. f shall callable (20.8.11.2) argument types argtypes , return type r. copy constructor , destructor of a shall not throw exceptions.