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#include <iostream>
using namespace std;
 
template <class T>
struct identity
{
    typedef T type;
};
 
template <class T>
T&& forward(typename identity<T>::type&& a)
{
    return a;
}
 
 
int main() {
 
	int a;
	forward( a );
 
	return 0;
}

prog.cpp: In function ‘int main()’:
prog.cpp:20:13: error: no matching function for call to ‘forward(int&)’
  forward( a );
             ^
prog.cpp:20:13: note: candidates are:
prog.cpp:11:5: note: template<class T> T&& forward(typename identity<T>::type&&)
 T&& forward(typename identity<T>::type&& a)
     ^
prog.cpp:11:5: note:   template argument deduction/substitution failed:
prog.cpp:20:13: note:   couldn't deduce template parameter ‘T’
  forward( a );
             ^
In file included from /usr/include/c++/4.8/bits/stl_pair.h:59:0,
                 from /usr/include/c++/4.8/bits/stl_algobase.h:64,
                 from /usr/include/c++/4.8/bits/char_traits.h:39,
                 from /usr/include/c++/4.8/ios:40,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from prog.cpp:1:
/usr/include/c++/4.8/bits/move.h:87:5: note: template<class _Tp> constexpr _Tp&& std::forward(typename std::remove_reference<_From>::type&&)
     forward(typename std::remove_reference<_Tp>::type&& __t) noexcept
     ^
/usr/include/c++/4.8/bits/move.h:87:5: note:   template argument deduction/substitution failed:
prog.cpp:20:13: note:   couldn't deduce template parameter ‘_Tp’
  forward( a );
             ^
In file included from /usr/include/c++/4.8/bits/stl_pair.h:59:0,
                 from /usr/include/c++/4.8/bits/stl_algobase.h:64,
                 from /usr/include/c++/4.8/bits/char_traits.h:39,
                 from /usr/include/c++/4.8/ios:40,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from prog.cpp:1:
/usr/include/c++/4.8/bits/move.h:76:5: note: template<class _Tp> constexpr _Tp&& std::forward(typename std::remove_reference<_From>::type&)
     forward(typename std::remove_reference<_Tp>::type& __t) noexcept
     ^
/usr/include/c++/4.8/bits/move.h:76:5: note:   template argument deduction/substitution failed:
prog.cpp:20:13: note:   couldn't deduce template parameter ‘_Tp’
  forward( a );
             ^

Standard output is empty