g ++ C ++ 0x枚举类编译器警告 [英] g++ C++0x enum class Compiler Warnings

问题描述

我一直在将C ++类型安全的伪枚举的可怕混乱重构为新的C ++ 0x类型安全的枚举，因为它们的可读性更高。无论如何，我在导出的类中使用了它们，因此我将它们明确标记为要导出：

I've been refactoring my horrible mess of C++ type-safe psuedo-enums to the new C++0x type-safe enums because they're way more readable. Anyway, I use them in exported classes, so I explicitly mark them to be exported:

enum class  __attribute__((visibility("default"))) MyEnum : unsigned int
{
    One = 1,
    Two = 2
};

使用g ++编译会产生以下警告：

Compiling this with g++ yields the following warning:

类型属性在定义类型后被忽略

type attributes ignored after type is already defined

这似乎很奇怪，因为到目前为止据我所知，该警告旨在防止出现实际错误，例如：

This seems very strange, since, as far as I know, that warning is meant to prevent actual mistakes like:

class __attribute__((visibility("default"))) MyClass { };
class __attribute__((visibility("hidden")))  MyClass;

当然，我显然没有这样做，因为我只在 enum类的定义，并且我没有在其他任何地方重新定义或声明它（我可以用一个文件复制此错误）。

Of course, I'm clearly not doing that, since I have only marked the visibility attributes at the definition of the enum class and I'm not re-defining or declaring it anywhere else (I can duplicate this error with a single file).

最终，我无法使这段代码真正引起问题，但事实是，如果我更改值并重新编译使用者而不重新编译共享库，消费者传递了新的价值，而共享库不知道如何处理它们（尽管我不希望它首先发挥作用）。

Ultimately, I can't make this bit of code actually cause a problem, save for the fact that, if I change a value and re-compile the consumer without re-compiling the shared library, the consumer passes the new values and the shared library has no idea what to do with them (although I wouldn't expect that to work in the first place).

我太学究了吗？可以安全地忽略这一点吗？我怀疑是这样，但同时，出现此错误使我无法使用 Werror 进行编译，这使我感到不舒服。我真的很想看到这个问题消失。

Am I being way too pedantic? Can this be safely ignored? I suspect so, but at the same time, having this error prevents me from compiling with Werror, which makes me uncomfortable. I would really like to see this problem go away.

推荐答案

您可以传递 -Wno属性标志以关闭警告。

You can pass the -Wno-attributes flag to turn the warning off.

（可能是gcc中的错误？）

(It's probably a bug in gcc?)

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