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#include <type_traits>
 
template <class T>
class forward_if_wrapper {
 
    template <class U, class Enable = std::enable_if_t<std::is_lvalue_reference_v<U>>>
    static U forward(U&& u) {
        return u;
    }
 
    template <class U, class Enable = std::enable_if_t<!std::is_lvalue_reference_v<U>>>
    static U&& forward(U&& t) {
        return static_cast<U&&>(t);
    }
};
auto forward = [](auto&& t) { return forward_if_wrapper<decltype(t)>::forward(t); };
template <class T> auto forward_if = [](auto&& u) { return forward_if_wrapper<T>::forward(u); };
 
// --------
 
#include <stdio.h>
#include <vector>
 
template<class Elt>
void bar(Elt&& e) {
    printf("Called %s\n", __PRETTY_FUNCTION__);
}
 
template<class Container>
void foo(Container&& c) {
    for (auto&& elt : c) {
        bar(forward_if<Container>(elt));
    }
}
 
int main() {
    std::vector<int> v = {1,2};
    foo(v);
    foo(std::move(v));
}

In file included from /usr/include/c++/4.9/type_traits:35:0,
                 from prog.cpp:1:
/usr/include/c++/4.9/bits/c++0x_warning.h:32:2: error: #error This file requires compiler and library support for the ISO C++ 2011 standard. This support is currently experimental, and must be enabled with the -std=c++11 or -std=gnu++11 compiler options.
 #error This file requires compiler and library support for the \
  ^
prog.cpp:6:44: error: 'enable_if_t' in namespace 'std' does not name a template type
     template <class U, class Enable = std::enable_if_t<std::is_lvalue_reference_v<U>>>
                                            ^
prog.cpp:6:55: error: expected '>' before '<' token
     template <class U, class Enable = std::enable_if_t<std::is_lvalue_reference_v<U>>>
                                                       ^
prog.cpp:7:29: error: expected unqualified-id before '{' token
     static U forward(U&& u) {
                             ^
prog.cpp:11:44: error: 'enable_if_t' in namespace 'std' does not name a template type
     template <class U, class Enable = std::enable_if_t<!std::is_lvalue_reference_v<U>>>
                                            ^
prog.cpp:11:55: error: expected '>' before '<' token
     template <class U, class Enable = std::enable_if_t<!std::is_lvalue_reference_v<U>>>
                                                       ^
prog.cpp:12:31: error: expected unqualified-id before '{' token
     static U&& forward(U&& t) {
                               ^
prog.cpp:16:6: error: 'forward' does not name a type
 auto forward = [](auto&& t) { return forward_if_wrapper<decltype(t)>::forward(t); };
      ^
prog.cpp:17:25: error: 'forward_if' does not name a type
 template <class T> auto forward_if = [](auto&& u) { return forward_if_wrapper<T>::forward(u); };
                         ^
prog.cpp:25:13: error: expected ',' or '...' before '&&' token
 void bar(Elt&& e) {
             ^
prog.cpp:30:19: error: expected ',' or '...' before '&&' token
 void foo(Container&& c) {
                   ^
prog.cpp: In function 'void foo(Container)':
prog.cpp:31:14: error: expected unqualified-id before '&&' token
     for (auto&& elt : c) {
              ^
prog.cpp:31:14: error: expected ';' before '&&' token
prog.cpp:31:21: error: expected ';' before ':' token
     for (auto&& elt : c) {
                     ^
prog.cpp:31:21: error: expected primary-expression before ':' token
prog.cpp:31:21: error: expected ')' before ':' token
prog.cpp:31:21: error: expected primary-expression before ':' token
prog.cpp: In function 'int main()':
prog.cpp:37:30: error: in C++98 'v' must be initialized by constructor, not by '{...}'
     std::vector<int> v = {1,2};
                              ^
prog.cpp:39:9: error: 'move' is not a member of 'std'
     foo(std::move(v));
         ^
prog.cpp: In instantiation of 'void foo(Container) [with Container = std::vector<int>]':
prog.cpp:38:10:   required from here
prog.cpp:31:14: error: label 'elt' used but not defined
     for (auto&& elt : c) {
              ^

Standard output is empty