perfect forwarding, C++ (vc++)

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//Microsoft (R) C/C++ Optimizing Compiler Version 19.00.23506 for x64

#include <iostream>
#include <string>

void foo( std::string& )
{ std::cout << "1. non-const lvalue: void foo( std::string& )\n" ; }

void foo( const std::string& )
{ std::cout << "2. const lvalue: void foo( const std::string& )\n" ; }

void foo( std::string&& )
{ std::cout << "3. rvalue: void foo( const string&& )\n" ; }

template < typename T > void pass_through( T&& arg )
{
    const auto ref_type = [] { return std::is_lvalue_reference<T&&>::value ? "lvalue" : "rvalue" ; };

std::cout << "void pass_through( T&& ) - forwarding "
              << ref_type() << " reference\n\t" ;

foo( std::forward<T>(arg) ) ;
}

#define NOISY_CALL(actual_call) \
{\
    std::cout << "\ncall " << #actual_call << '\n' ;\
    actual_call ;\
    std::cout << '\n';\
}

int main()
{
    std::string non_const_str = "abcd";
    const std::string const_str = non_const_str ;

NOISY_CALL( foo(non_const_str) )
    // call foo(non_const_str)
    // 1. non-const lvalue: void foo( std::string& )

NOISY_CALL( foo(const_str) )
    // call foo(const_str)
    // 2. const lvalue: void foo( const std::string& )

NOISY_CALL( foo( std::move(non_const_str) ) )
    // call foo( std::move(non_const_str) )
    // 3. rvalue: void foo( const string&& )

NOISY_CALL( pass_through(non_const_str) ) ;
    // call pass_through(non_const_str)
    // void pass_through( T&& ) - forwarding lvalue reference
    //     1. non-const lvalue: void foo( std::string& )

NOISY_CALL( pass_through(const_str) ) ;
    // call pass_through(const_str)
    // void pass_through( T&& ) - forwarding lvalue reference
    //        2. const lvalue: void foo( const std::string& )

NOISY_CALL( pass_through( std::move(non_const_str) ) ) ;
    // call pass_through( std::move(non_const_str) )
    // void pass_through( T&& ) - forwarding rvalue reference
    //        3. rvalue: void foo( const string&& )
}

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Compilation time: 1,83 sec, absolute running time: 0,21 sec, absolute service time: 2,06 sec