使用 stdlibc++ 4.7 启用 C++11 时，clang 错误，而 gcc 编译正常

Question

我一直在尝试让 C++11 工作，在浏览了不同的网站和 Q/A 之后，我仍然遇到问题。我想在 libstdc++ 中使用 clang。在 clang 状态中表明它受补丁支持 - http://clang.llvm.org/libstdc++4.7-clang11.patch。我从 macports 下载 gcc4.7 并在 gcc4.7 的标题中进行了相应的更改

我不使用 libc++ 的原因是因为 libc++ 和 libstdc++ 之间的 ABI 兼容性，由该线程指示：Why can't clang with libc++ in c++0x mode link this boost::program_options example?

好的，一切都完成后，我用以下代码测试了我的设置：

#include <mutex>
#include <thread>

int main ( ) {
    std::mutex myMutext;
    return 0;
}

我希望包含应该在 c++11 下工作。

所以这是我编译它的方法： 与 GCC

g++ -std=c++11 -I/opt/local/include/gcc47/c++ -L/opt/local/lib/gcc47 main.cpp -o main

编译成功

使用 Clang

clang++ -std=c++11 -I/opt/local/include/gcc47/c++ -L/opt/local/lib/gcc47 main.cpp -o main

我收到此错误：

@work:boostTest$ clang++ -std=c++11 -I/opt/local/include/gcc47/c++ -L/opt/local/lib/gcc47 main.cpp -o main
In file included from main.cpp:1:
In file included from /opt/local/include/gcc47/c++/mutex:38:
In file included from /opt/local/include/gcc47/c++/tuple:37:
In file included from /opt/local/include/gcc47/c++/utility:70:
/opt/local/include/gcc47/c++/bits/stl_relops.h:72:3: error: unknown type name '_GLIBCXX_BEGIN_NAMESPACE_VERSION'
  _GLIBCXX_BEGIN_NAMESPACE_VERSION
  ^
/opt/local/include/gcc47/c++/bits/stl_relops.h:86:5: error: expected unqualified-id
    template <class _Tp>
    ^
In file included from main.cpp:1:
In file included from /opt/local/include/gcc47/c++/mutex:38:
In file included from /opt/local/include/gcc47/c++/tuple:37:
In file included from /opt/local/include/gcc47/c++/utility:71:
In file included from /opt/local/include/gcc47/c++/bits/stl_pair.h:61:
/opt/local/include/gcc47/c++/bits/move.h:38:1: error: unknown type name '_GLIBCXX_BEGIN_NAMESPACE_VERSION'
_GLIBCXX_BEGIN_NAMESPACE_VERSION
^
/opt/local/include/gcc47/c++/bits/move.h:45:3: error: expected unqualified-id
  template<typename _Tp>
  ^
In file included from main.cpp:1:
In file included from /opt/local/include/gcc47/c++/mutex:38:
In file included from /opt/local/include/gcc47/c++/tuple:37:
In file included from /opt/local/include/gcc47/c++/utility:71:
In file included from /opt/local/include/gcc47/c++/bits/stl_pair.h:61:
In file included from /opt/local/include/gcc47/c++/bits/move.h:57:
/opt/local/include/gcc47/c++/type_traits:41:1: error: unknown type name '_GLIBCXX_BEGIN_NAMESPACE_VERSION'
_GLIBCXX_BEGIN_NAMESPACE_VERSION
^
/opt/local/include/gcc47/c++/type_traits:55:3: error: expected unqualified-id
  template<typename _Tp, _Tp __v>
  ^
/opt/local/include/gcc47/c++/type_traits:65:11: error: unknown type name 'integral_constant'
  typedef integral_constant<bool, true>     true_type;
          ^
/opt/local/include/gcc47/c++/type_traits:65:28: error: expected unqualified-id
  typedef integral_constant<bool, true>     true_type;
                           ^
/opt/local/include/gcc47/c++/type_traits:68:11: error: unknown type name 'integral_constant'
  typedef integral_constant<bool, false>    false_type;
          ^
/opt/local/include/gcc47/c++/type_traits:68:28: error: expected unqualified-id
  typedef integral_constant<bool, false>    false_type;
                           ^
/opt/local/include/gcc47/c++/type_traits:71:36: error: expected ';' after top level declarator
    constexpr _Tp integral_constant<_Tp, __v>::value;
                                   ^
/opt/local/include/gcc47/c++/type_traits:83:14: error: expected class name
    : public false_type
             ^
/opt/local/include/gcc47/c++/type_traits:106:14: error: expected class name
    : public true_type
             ^
/opt/local/include/gcc47/c++/type_traits:126:14: error: unknown template name 'integral_constant'
    : public integral_constant<bool, !_Pp::value>
             ^
/opt/local/include/gcc47/c++/type_traits:126:38: error: expected class name
    : public integral_constant<bool, !_Pp::value>
                                     ^
/opt/local/include/gcc47/c++/type_traits:142:14: error: expected class name
    : public false_type { };
             ^
/opt/local/include/gcc47/c++/type_traits:146:14: error: expected class name
    : public true_type { };
             ^
/opt/local/include/gcc47/c++/type_traits:151:14: error: unknown template name 'integral_constant'
    : public integral_constant<bool, (__is_void_helper<typename
             ^
/opt/local/include/gcc47/c++/type_traits:151:38: error: expected class name
    : public integral_constant<bool, (__is_void_helper<typename
                                     ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.

我使用的是 clang 版本：

Apple clang version 4.0 (tags/Apple/clang-418.2.41) (based on LLVM 3.1svn)
Target: x86_64-apple-darwin11.3.0
Thread model: posix

我做错了吗？或者这是最新的 gcc 4.7 libstc++ 的问题？

Answer 1

你为什么说-I/opt/local/include/gcc47/c++？

这对于 GCC 或 Clang 都不是必需的，并且不会起作用。并非所有的 libstdc++ 头文件都在该路径下，其他地方有一些基本的头文件定义了 _GLIBCXX_BEGIN_NAMESPACE_VERSION

GCC 不会失败，因为 GCC 已经知道如何找到其他标头，因此显式使用 -I 和 -L 选项是多余的。它不适用于 Clang，因为您只是告诉它如何找到它需要的一些标头，而不告诉它如何找到其余部分。

停止尝试覆盖编译器的标准库路径，让它使用它已经知道的内置路径。

Answer 2

我在 FreeBSD 9.0/AMD64 上使用 clang-3.1 和 gcc4.6 libstdc++。它适用于以下选项：

-I/usr/local/lib/gcc46/include/c++ \
-I/usr/local/lib/gcc46/include/c++/x86_64-portbld-freebsd9.0 \
-L/usr/local/lib/gcc46

我想你的问题可以通过使用这些选项来解决：

-I/opt/local/include/gcc47/c++ \
-I/opt/local/include/gcc47/c++/x86_64-apple-darwin11.3.0 \
-L/opt/local/lib/gcc47

Answer 3

可以使用special option -gcc-toolchain，在编译clang时由--with-gcc-toolchain隐式设置。当你想使用另一个 GCC 库时，它比重新编译 clang 容易一点:)

这样：

~/clang/trunk/bin/clang++ main.cc -gcc-toolchain ~/gcc/trunk -o main

或者，在你的情况下（我知道它已经 4 岁了:)）它似乎是

clang++ main.cpp -o main -gcc-toolchain /opt/local

“toolchain”文件夹应包含“include”和“lib”文件夹。编译器和链接器都使用此选项。请注意：--gcc-toolchain 不是一个有效选项，请使用一个破折号作为前缀（尽管 llvm wiki 另有说明——我在 clang 3.8 主干上检查过）。