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您可以根据双重ABI发布您的库。这或多或少地类似于OSXfat binary，但是完全用C ++构建。

最简单的方法是两次编译库： code> -D_GLIBCXX_USE_CXX11_ABI = 0 并使用 -D_GLIBCXX_USE_CXX11_ABI = 1 。将整个库放在两个不同的命名空间下，具体取决于宏的值：

  #if _GLIBCXX_USE_CXX11_ABI 
＃define DUAL_ABI cxx11 __attribute __（（abi_tag（cxx11）））
 #else 
＃define DUAL_ABI cxx03 
 #endif 

命名空间CryptoPP {
内联命名空间DUAL_ABI {
 // library goes here 
} 
} 
 

您的用户可以照常使用 CryptoPP :: whatever ，这映射到 CryptoPP :: cxx11 :: whatever 或 CryptoPP :: cxx03 :: whatever 取决于所选的ABI。

注意，GCC手册说，改变在标记的inline命名空间中定义的一切的名称。

另一种方法是使用 __ attribute __（（abi_tag（ cxx11）））如果 _GLIBCXX_USE_CXX11_ABI 不为零。此属性很好地将 [cxx11] 添加到demangler的输出。我认为使用命名空间的工作原理也很好，并且对现有代码的修改较少。

理论上，您不需要复制整个库，只有使用 std :: string 和 std :: list 的函数和类，这些函数和类，等等。但在实践中，这可能不值得的努力，特别是如果图书馆不是很大。

We recently caught a report because of GCC 5.1, libstdc++ and Dual ABI. It seems Clang is not aware of the GCC inline namespace changes, so it generates code based on one set of namespaces or symbols, while GCC used another set of namespaces or symbols. At link time, there are problems due to missing symbols.

If I am parsing the Dual ABI page correctly, it looks like a matter of pivoting on _GLIBCXX_USE_CXX11_ABI and abi::cxx11 with some additional hardships. More reading is available on Red Hat's blog at GCC5 and the C++11 ABI and The Case of GCC-5.1 and the Two C++ ABIs.

Below is from a Ubuntu 15 machine. The machine provides GCC 5.2.1.

$ cat test.cxx
#include <string>

std::string foo __attribute__ ((visibility ("default")));
std::string bar __attribute__ ((visibility ("default")));

$ g++ -g3 -O2 -shared test.cxx -o test.so

$ nm test.so | grep _Z3
...
0000201c B _Z3barB5cxx11
00002034 B _Z3fooB5cxx11

$ echo _Z3fooB5cxx11 _Z3barB5cxx11 | c++filt 
foo[abi:cxx11] bar[abi:cxx11]

How can I generate a binary with symbols using both decorations ("coexistence" as the Red Hat blog calls it)?

Or, what are the options available to us?

---

I'm trying to achieve an "it just works" for users. I don't care if there are two weak symbols with two different behaviors (std::string lacks copy-on-write, while std::string[abi:cxx11] provides copy-on-write). Or, one can be an alias for the other.

Debian has a boatload of similar bugs at Debian Bug report logs: Bugs tagged libstdc++-cxx11. Their solution was to rebuild everything under the new ABI, but it did not handle the corner case of mixing/matching compilers modulo the ABI changes.

In the Apple world, I think this is close to a fat binary. But I'm not sure what to do in the Linux/GCC world. Finally, we don't control how the distro's build the library, and we don't control what compilers are used to link an applications with the library.

Disclaimer, the following is not tested in production, use at your own risk.

You can yourself release your library under dual ABI. This is more or less analogous to OSX "fat binary", but built entirely with C++.

The easiest way to do so would be to compile the library twice: with -D_GLIBCXX_USE_CXX11_ABI=0 and with -D_GLIBCXX_USE_CXX11_ABI=1. Place the entire library under two different namespaces depending on the value of the macro:

#if _GLIBCXX_USE_CXX11_ABI
#  define DUAL_ABI cxx11 __attribute__((abi_tag("cxx11")))
#else
#  define DUAL_ABI cxx03
#endif

namespace CryptoPP {
  inline namespace DUAL_ABI {
    // library goes here
  }
}

Now your users can use CryptoPP::whatever as usual, this maps to either CryptoPP::cxx11::whatever or CryptoPP::cxx03::whatever depending on the ABI selected.

Note, the GCC manual says that this method will change mangled names of everything defined in the tagged inline namespace. In my experience this doesn't happen.

The other method would be tagging every class, function, and variable with __attribute__((abi_tag("cxx11"))) if _GLIBCXX_USE_CXX11_ABI is nonzero. This attribute nicely adds [cxx11] to the output of the demangler. I think that using a namespace works just as well though, and requires less modification to the existing code.

In theory you don't need to duplicate the entire library, only functions and classes that use std::string and std::list, and functions and classes that use these functions and classes, and so on recursively. But in practice it's probably not worth the effort, especially if the library is not very big.