使用C ++打开不存在的文件未捕获到异常 [英] Exception not caught opening a non-existing file using C++

问题描述

我从此处运行MWE：
http：// www .cplusplus.com / reference / ios / ios / exceptions /
在我的计算机上，它没有捕获到异常。这是我的代码

I was running a MWE from here: http://www.cplusplus.com/reference/ios/ios/exceptions/ On my machine it does not catch the exception. Here is my code

#include <iostream>
#include <fstream>

int main()
{
    std::ifstream file;
    file.exceptions( std::ifstream::failbit | std::ifstream::badbit );
    try
    {
        file.open("IDoNotExist.txt");
    }
    catch(const std::ifstream::failure& e)
    {
        std::cout << "Bad luck!" << std::endl;
    }
}

使用 gcc 6.2.1 我得到：

在抛出'std :: ios_base :: failure'实例后调用终止

terminate called after throwing an instance of 'std::ios_base::failure'

what（）：basic_ios :: clear

what(): basic_ios::clear

但是，在上面发布的链接中提到代码也应该捕获异常与打开文件有关。出了什么问题？

However, on the link posted above it is mentioned that the code should also catch the exception related to opening the file. What went wrong?

推荐答案

它看起来像是 libstdc ++中的已知错误。

问题在于更改为C ++ 11 ABI，许多类在 libstdc ++ 6.so 中重复，一个版本使用旧的ABI，另一个版本使用新的ABI。

The problem is that with the change to the C++11 ABI, many classes were duplicated in libstdc++6.so, one version with the old ABI, other with the new one.

异常类没有重复，因此该问题当时不存在。但是，随后，在对该语言的一些较新版本中，决定 std :: ios_base :: failure 应该源自 std :: system_error 而不是 std :: exception ...，但是 system_error 是C ++ 11唯一的类因此它必须使用新的ABI标志，否则它将抱怨。现在，您有了两个不同的 std :: ios_base :: failure 类，并且手头一团糟！

Exception classes were not duplicated so this problem didn't exist at the time. But then, in some newer revision of the language, it was decided that std::ios_base::failure should derive from std::system_error instead of std::exception... but system_error is a C++11 only class so it must use the new ABI flag or it will complain. Now you have two different std::ios_base::failure classes and a mess in your hands!

简单解决方案是使用 -D_GLIBCXX_USE_CXX11_ABI = 0 编译您的程序，然后辞职到旧的ABI，直到错误解决为止。或者，编写 catch（std :: exception& e）。

The easy solution is to compile your program with -D_GLIBCXX_USE_CXX11_ABI=0 and resign to the old ABI until the bug is solved. Or alternatively, write catch (std::exception &e).

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