std :: promise< T>在Visual Studio 2017中T必须是默认可构造的地方? [英] std::promise<T> where T must be default constructible in Visual Studio 2017?

问题描述

我正在尝试在Visual Studio 2017中编译以下代码:

I am trying to compile the following code in Visual Studio 2017:

#include <future>

int main()
{
    std::promise<std::reference_wrapper<int>> promise;
    (void)promise;
}

但是，出现以下错误:

错误C2512:"std :: reference_wrapper":没有合适的默认构造函数

error C2512: 'std::reference_wrapper': no appropriate default constructor available

它可以与GCC和Clang一起很好地编译.

Whereas it compiles fine with GCC and Clang.

这是Visual Studio中的确定错误，还是std :: promise的有效实现?

Is this is a definite bug in Visual Studio or is it a valid implementation of std::promise?

推荐答案

看起来像是一个

Looks like it is a known issue in MSVC's standard library implementation. A simpler reproduction scenario:

#include <future>
struct NoDefaultCtor
{
    NoDefaultCtor() = delete;
};
int main() {
    std::promise<NoDefaultCtor> p;
    return 0;
}

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