应该std :: unique_ptr< void>允许 [英] Should std::unique_ptr<void> be permitted

问题描述

这是一个很简单的问题。考虑下面的代码：

This is a very simple question. Consider the following code:

#include <iostream>
#include <memory>

typedef std::unique_ptr<void> UniqueVoidPtr;

int main() {
    UniqueVoidPtr p(new int);
    return 0;
}

使用以下命令使用cygwin（g ++ 4.5.3）进行编译 g ++ -std = c ++ 0x -o prog file.cpp 工作正常。但是，使用微软编译器（VS 2010或2013）编译我得到这个错误：

Compiling with cygwin (g++ 4.5.3) with the following command g++ -std=c++0x -o prog file.cpp works just fine. However, compiling with the microsoft compiler (either VS 2010 or 2013) I get this error:

C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\memory(2067) : error C2070: 'void': illegal sizeof operand
        C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\memory(2066) : while compiling class template member function 'void std::default_delete<_Ty>::operator ()(_Ty *) const'
        with
        [
            _Ty=void
        ]
        C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\type_traits(650) : see reference to class template instantiation 'std::default_delete<_Ty>' being compiled
        with
        [
            _Ty=void
        ]
        C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\INCLUDE\memory(2193) : see reference to class template instantiation 'std::tr1::is_empty<_Ty>' being compiled
        with
        [
            _Ty=std::default_delete<void>
        ]
        foo1.cpp(7) : see reference to class template instantiation 'std::unique_ptr<_Ty>' being compiled
        with
        [
            _Ty=void
        ]

这是否预期？我在写一个类，我想在类中有一个唯一的指针。当试图找出类的移动构造函数的语义时，我遇到了这个（我假设因为我最终得到我的移动构造函数正确编码：即其他错误是固定的）。

Is this expected? I'm writing a class where I wanted to have a unique pointer in the in the class. While trying to work out the semantics of a move constructor for the class, I ran into this (I assume because I finally got my move constructor coded correctly: i.e. the other errors were fixed).

推荐答案

MSVC是正确的，而GCC错误：
标准（3.9 / 5）：不完全定义的对象类型和void类型不完整的
类型
标准（20.7.1.1.2 / 4）：如果T是不完整的类型，程序是错误的

MSVC is right while GCC is wrong: Standard(3.9/5): Incompletely-defined object types and the void types are incomplete types Standard(20.7.1.1.2/4): If T is an incomplete type, the program is ill-formed

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