使用VC2017编译简单的std :: variant测试时出错C2280 15.7.3

Question

VC尝试使用copy operator =而不是移动版本

您好，

我尝试用VS2017 15.7.3＆amp;编译以下代码。 / STD：C ++最新：

 

    #include "variant"

    struct OptionOne {
    OptionOne() {}
    OptionOne(OptionOne&& other) noexcept = default;
    OptionOne(const OptionOne& other) = delete;

    int X = 2;
    };

    struct OptionTwo {
    OptionTwo() {}
    OptionTwo(OptionTwo&& other) noexcept = default;
    OptionTwo(const OptionTwo& other) = delete;

    int X = 4;
    };

    using Store = std::variant;

    int main()
    {
    Store test;
    OptionTwo two;


    test = std::move(two);

        return 0;
    }

 

此代码无法编译，并显示错误消息：

 

    >c:\users\jean\source\repos\variant\variant.cpp(32): error C2280: 'std::variant &std::variant::operator =(const std::variant &)': attempting to reference a deleted function
    1>c:\program files (x86)\microsoft visual studio\2017\enterprise\vc\tools\msvc\14.14.26428\include\variant(1343): note: compiler has generated 'std::variant::operator =' here
    1>c:\program files (x86)\microsoft visual studio\2017\enterprise\vc\tools\msvc\14.14.26428\include\variant(1343): note: 'std::variant &std::variant::operator =(const std::variant &)': function was implicitly deleted because a base class invokes a deleted or inaccessible function 'std::_Deleted_move_assign &std::_Deleted_move_assign::operator =(const std::_Deleted_move_assign &)'
    1>        with
    1>        [
    1>            _Base=std::_Variant_base
    1>        ]
    1>c:\program files (x86)\microsoft visual studio\2017\enterprise\vc\tools\msvc\14.14.26428\include\xsmf_control.h(162): note: 'std::_Deleted_move_assign &std::_Deleted_move_assign::operator =(const std::_Deleted_move_assign &)': function was implicitly deleted because a base class invokes a deleted or inaccessible function 'std::_Deleted_copy_assign &std::_Deleted_copy_assign::operator =(const std::_Deleted_copy_assign &)'
    1>        with
    1>        [
    1>            _Base=std::_Variant_base
    1>        ]
    1>c:\program files (x86)\microsoft visual studio\2017\enterprise\vc\tools\msvc\14.14.26428\include\xsmf_control.h(109): note: 'std::_Deleted_copy_assign &std::_Deleted_copy_assign::operator =(const std::_Deleted_copy_assign &)': function was explicitly deleted
    1>        with
    1>        [
    1>            _Base=std::_Variant_base
    1>        ]
 

据我所知，这个错误信息似乎是编译器试图将（删除）复制操作符用于已删除的变体。

以我的拙见，它应该使用operator =的移动版本。

这段代码有什么问题吗？

谢谢你的帮助！ 让