Can I list-initialize a vector of move-only type?

Question

If I pass the following code through my GCC 4.7 snapshot, it tries to copy the unique_ptrs into the vector.

#include 
#include <         


        

Answer 1

Using Johannes Schaub's trick of std::make_move_iterator() with std::experimental::make_array(), you can use a helper function:

#include 
#include 
#include 
#include 

struct X {};

template
auto make_vector( std::array&& a )
    -> std::vector
{
    return { std::make_move_iterator(std::begin(a)), std::make_move_iterator(std::end(a)) };
}

template
auto make_vector( T&& ... t )
    -> std::vector::type>
{
    return make_vector( std::experimental::make_array( std::forward(t)... ) );
}

int main()
{
    using UX = std::unique_ptr;
    const auto a  = std::experimental::make_array( UX{}, UX{}, UX{} ); // Ok
    const auto v0 = make_vector( UX{}, UX{}, UX{} );                   // Ok
    //const auto v1 = std::vector< UX >{ UX{}, UX{}, UX{} };           // !! Error !!
}

See it live on Coliru.

Perhaps someone can leverage std::make_array()'s trickery to allow make_vector() to do its thing directly, but I did not see how (more accurately, I tried what I thought should work, failed, and moved on). In any case, the compiler should be able to inline the array to vector transformation, as Clang does with O2 on GodBolt.