Creating list of unique_ptr using initialization list and make

I am using GCC 5.4 for compiling a test program in C 14.

#include <type_traits>
#include <list>
#include <iostream>
#include <memory>

int main()
{
    int VALUE = 42;
    const auto list_ = {
        std::make_unique<int>(VALUE),
        std::make_unique<int>(0),
        std::make_unique<int>(0)
    };
}

GCC 5.4 fails with the below error message:

<source>: In function 'int main()':
<source>:13:5: error: use of deleted function 'std::unique_ptr<_Tp, _Dp>::unique_ptr(const std::unique_ptr<_Tp, _Dp>&) [with _Tp = int; _Dp = std::default_delete<int>]'
     };
     ^
In file included from /opt/compiler-explorer/gcc-5.4.0/include/c  /5.4.0/memory:81:0,
                 from <source>:4:
/opt/compiler-explorer/gcc-5.4.0/include/c  /5.4.0/bits/unique_ptr.h:356:7: note: declared here
       unique_ptr(const unique_ptr&) = delete;
       ^

The same code compiles properly with Clang 3.5. See https://godbolt.org/z/PM776xGP4

The issue seems to be there until GCC 9.2 where it compiles properly.

Is this a known bug in GCC 9.1 and below? If yes, is there a way to solve this using the initializer list?

CodePudding user response：

You can use:

const std::initializer_list<std::unique_ptr<int>> list{
    std::make_unique< int >( 42 ),
    std::make_unique< int >( 0 ),
    std::make_unique< int >( 0 )
};

Demo (old gcc-5.4 tested).