Question

我正在查看最近发布的C ++编程语言第4版，查看新功能。我正在使用VS2012 Update 3（VC11）编译器，（我不知道，但这是我必须使用的。）

17.6生成默认操作状态：

• If the programmer declares any constructor for a class, the default constructor
is not generated for that class.

• If the programmer declares a copy operation, a move operation, or a destructor
for a class, no copy operation, move operation, or destructor is generated for
that class.

我对此的解读是，如果我为一个类声明了一个复制构造函数，那么编译器就会生成复制和移动操作，并且所有析构函数都应该被抑制。

然而在VS2012中，我看到了这一点：

struct H{}; // Compiler generated default, copy and move constructors, and
            // destructor. 

struct J
{
    explicit J(int){}
    J(const J&){}   // User copy constructor, so compiler generated default,
                    // copy or move operations and destructor should be
                    // suppressed.
};

void Foo()
{
    H h1;               // Compiler generated default construct.
    H h2 = h1;          // Compiler generated copy construct;
    h1 = h2;            // Compiler generated copy assign.
    H h3 = move(h1);    // Compiler generated move construct.
    h3 = move(h2);      // Compiler generated move assign.

//  J j1;               // Correct. Does not compile. No compiler generated default
                        // constructor.
    J j2(1);            // User constructor.
    J j3 = j2;          // User copy constructor.
    j2 = j3;            // Error? Generated copy assignment should be suppressed.
    J j4 = move(j2);    // Error? Generated move constructor should be suppressed.
    j3 = move(j4);      // Error? Generated move assignment should be suppressed.
}

我误解了，还是书或编译器错了？

VS2012复制和移动操作生成是否正确？

0 个答案: