Enum定义在课堂上很重要 [英] Enum defintion matters in class

问题描述

您好，

将Visual Studio 2015更新为Update 3后，我遇到了问题。我有 下面定义了两个A和B类。 B有一个默认参数的ctor。

I run into a problem after updating my visual studio 2015 to Update 3. I have  two classes A and B defined below. B has a ctor with default parameter.

class A
{
public:
	A(int idd)
		:i(idd)
	{}
	enum { IDD = 1 };
	int i;
};

class B : public A
{
public:

B（int idd = B :: IDD）
：A（idd）
{}
enum {IDD = 2};
};

int main（）
{
B b = B（）;

返回0;
}

B(int idd = B::IDD) :A(idd) {} enum { IDD = 2 }; }; int main() { B b=B(); return 0; }

当在B类枚举定义位于ctor定义之后时，默认参数实际上是值1（A :: IDD）而不是2.

当我在ctor之前移动枚举定义时，默认参数是2，正如我预期的那样。

When in class B enum definition is located after ctor definition, default parameter has actually value 1 (A::IDD) instead of 2.

When I moved enum definition before the ctor, default parameter is 2 as I expected.

在Update 3之前，默认参数始终为2，无论它位于何处。

Before Update 3 default parameter was always 2 no matter where it was located.

感谢您的回答

推荐答案

On 6/27/2017 10:15 AM， ginCat写道：

On 6/27/2017 10:15 AM, ginCat wrote:

在更新3之前，默认参数始终为2，无论它位于何处。我找不到有关此编译器更改的任何信息 发行说明中的​​行为。根据C ++标准，这是正确的行为吗？

Before Update 3 default parameter was always 2 no matter where it was located.I couldn't find any information about this change of compiler  behavior in release notes. Is it correct behavior according to C++ standard?

对我来说看起来像个错误。我对标准的解读是bi应该是2. Clang和GCC都同意。

Looks like a bug to me. My reading of the standard is that b.i should be 2. Clang and GCC both agree.

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