C ++ std库与不同的C ++标准链接 [英] C++ std library linking with different C++ standards

问题描述

我正在使用Cygwin（GCC v4.5.0）编译项目，我有一个奇怪的链接器问题。

错误：未定义引用 std :: basic_string< char， std :: char_traits< char>，std :: allocator< char> > :: basic_string（std :: basic_string< char，std :: char_traits< char>，std :: allocator< char>&&&&&）

但是，当我使用gcc编译器标志编译时，链接失败：
-std = c ++ 0x



一些注释：

ol>

我通知gcc手动链接标准库和编译器标志： -lstdc ++

符号依赖性源于Boost库头文件（v.1.45.0）：
boost :: units :: detail :: utility.hpp，function：std :: string demangle const char * name）;

应用程序使用MinGW gcc v4.5.0正确编译和链接。

问题：

1. 编译标准库通常包含不同的C ++标准符号？


2. 为什么链接器找不到的符号 std :: basic_string 当我可以保证它可以找到 libstdc ++。a ？

先感谢大家。

-JT

解决方案

是的，标准和技术报告的新修订版对标准库的内容进行了很多更改。您在C ++ 0x的标准库中新添加了您引用的函数（ std :: string 的 move constructor ）。

标准的版本不会影响名称调整，虽然编译器版本，并且需要更新的编译器更好的C + + 0x支持，所以它可能似乎是相关的。 p>

您可能使用的是旧版本的libstdc ++。

编辑：基本疑难解答：

  $ find / usr -name libstdc ++。a 
 /usr/lib/gcc/i686-pc-cygwin/4.5.0/libstdc++。 a 
 
 $ cygcheck -f /usr/lib/gcc/i686-pc-cygwin/4.5.0/libstdc++.a 
 libstdc ++ 6-devel-4.5.0-1 
 
 $ nm -C /usr/lib/gcc/i686-pc-cygwin/4.5.0/libstdc++.a | grep basic_string | grep'&&'
 00000000 T std :: basic_string< char，std :: char_traits< char>，std :: allocator< char> > :: basic_string（std :: string&&）
 00000000 T std :: basic_string< char，std :: char_traits< char>，std :: allocator< char> > :: basic_string（std :: string&&）
 00000000 T std :: basic_string< wchar_t，std :: char_traits< wchar_t>，std :: allocator< wchar_t> > :: assign（std :: basic_string< wchar_t，std :: char_traits< wchar_t>，std :: allocator< wchar_t>&&&&）
 00000000 T std :: basic_string< wchar_t，std： ：char_traits< wchar_t>，std :: allocator< wchar_t> > :: basic_string（std :: basic_string< wchar_t，std :: char_traits< wchar_t>，std :: allocator< wchar_t>&&&）
 00000000 T std :: basic_string< wchar_t，std： ：char_traits< wchar_t>，std :: allocator< wchar_t> > :: basic_string（std :: basic_string< wchar_t，std :: char_traits< wchar_t>，std :: allocator< wchar_t>&&&）
 00000000 T std :: basic_string< wchar_t，std： ：char_traits< wchar_t>，std :: allocator< wchar_t> > :: operator =（std :: basic_string< wchar_t，std :: char_traits< wchar_t>，std :: allocator< wchar_t>>&&& amp;）
  

这看起来有点滑稽。 std :: wstring 的定义（即 std :: basic_string< wchar_t，std :: char_traits< wchar_t>，std :: allocator< wchar_t& > ）看起来正确，窄版本没有。 std :: string 应该永远不会生存到磨损阶段，因为它只是一个typedef。

然而，我在linux上得到相同的输出：

 ％find / usr -name libstdc ++。a 
 / usr /lib64/gcc/x86_64-pc-linux-gnu/3.4.6/libstdc++.a 
 /usr/lib64/gcc/x86_64-pc-linux-gnu/3.4.6/32/libstdc++.a 
 /usr/lib64/gcc/x86_64-pc-linux-gnu/4.5.2/libstdc++.a 
 /usr/lib64/gcc/x86_64-pc-linux-gnu/4.5.2/32/libstdc++ .a 
 
％nm -C /usr/lib64/gcc/x86_64-pc-linux-gnu/4.5.2/libstdc++.a | grep basic_string | grep'&&'
 0000000000000000 W std :: basic_string< char，std :: char_traits< char>，std :: allocator< char> > :: basic_string（std :: string&&）
 0000000000000000 W std :: basic_string< char，std :: char_traits< char>，std :: allocator< char> > :: basic_string（std :: string&&）
 0000000000000000 W std :: basic_string< wchar_t，std :: char_traits< wchar_t>，std :: allocator< wchar_t> > :: assign（std :: basic_string< wchar_t，std :: char_traits< wchar_t>，std :: allocator< wchar_t>&&&&）
 0000000000000000 W std :: basic_string< wchar_t，std： ：char_traits< wchar_t>，std :: allocator< wchar_t> > :: basic_string（std :: basic_string< wchar_t，std :: char_traits< wchar_t>，std :: allocator< wchar_t>&&&）
 0000000000000000 W std :: basic_string< wchar_t，std： ：char_traits< wchar_t>，std :: allocator< wchar_t> > :: basic_string（std :: basic_string< wchar_t，std :: char_traits< wchar_t>，std :: allocator< wchar_t>&&&）
 0000000000000000 W std :: basic_string< wchar_t，std： ：char_traits< wchar_t>，std :: allocator< wchar_t> > :: operator =（std :: basic_string< wchar_t，std :: char_traits< wchar_t>，std :: allocator< wchar_t>>&&& amp;）
  

I am compiling a project using Cygwin (GCC v4.5.0) and I'm having an odd linker problem. I am hoping somebody with some expertise can help.

Error: undefined reference to std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::basic_string<char, std::char_traits<char>, std::allocator<char> >&&)

However, the linking only fails when I compile with the gcc compiler flag: -std=c++0x It succeeds when I don't specify the standard.

Some notes:

1. I am informing gcc to link the standard library manually with the compiler flag: -lstdc++
2. The symbol dependency is originating from a Boost library header file (v.1.45.0): boost::units::detail::utility.hpp, function: std::string demangle(const char* name);
3. The application compiles and links properly using MinGW gcc v4.5.0.

Questions:

1. Does the compiled standard library usually contain different symbols for different C++ standards?
2. Does the name mangling of symbols change with different C++ standards in GCC?
3. Why can't the linker find the symbols for std::basic_string when I can guarantee that it can find libstdc++.a?

Thanks in advance everyone.

-JT

解决方案

Yes, both new revisions of the standard and technical reports make many changes to the content of the standard library. The function you referenced (std::string's move constructor) is newly added in C++0x's standard library.

The version of the standard does not affect name mangling, although the compiler version does, and newer compilers are needed for better C++0x support, so it could appear to be related.

You are probably using too old a version of libstdc++.

EDIT: Basic troubleshooting:

$ find /usr -name libstdc++.a
/usr/lib/gcc/i686-pc-cygwin/4.5.0/libstdc++.a

$ cygcheck -f /usr/lib/gcc/i686-pc-cygwin/4.5.0/libstdc++.a
libstdc++6-devel-4.5.0-1

$ nm -C /usr/lib/gcc/i686-pc-cygwin/4.5.0/libstdc++.a | grep basic_string | grep '&&'
00000000 T std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::string&&)
00000000 T std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::string&&)
00000000 T std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >::assign(std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >&&)
00000000 T std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >::basic_string(std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >&&)
00000000 T std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >::basic_string(std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >&&)
00000000 T std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >::operator=(std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >&&)

This does indeed look a little funny. The definitions for std::wstring (i.e. std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >) look correct, the narrow versions do not. The name std::string shouldn't ever have survived to the mangling stage, since it's just a typedef.

However, I get the same output on linux:

% find /usr -name libstdc++.a
/usr/lib64/gcc/x86_64-pc-linux-gnu/3.4.6/libstdc++.a
/usr/lib64/gcc/x86_64-pc-linux-gnu/3.4.6/32/libstdc++.a
/usr/lib64/gcc/x86_64-pc-linux-gnu/4.5.2/libstdc++.a
/usr/lib64/gcc/x86_64-pc-linux-gnu/4.5.2/32/libstdc++.a

% nm -C /usr/lib64/gcc/x86_64-pc-linux-gnu/4.5.2/libstdc++.a | grep basic_string | grep '&&'
0000000000000000 W std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::string&&)
0000000000000000 W std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::string&&)
0000000000000000 W std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >::assign(std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >&&)
0000000000000000 W std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >::basic_string(std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >&&)
0000000000000000 W std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >::basic_string(std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >&&)
0000000000000000 W std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >::operator=(std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >&&)

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