建筑的未定义符号x86_64 - Mavericks(Yosemite,El Capitan ...)

编辑:

如果你落在这篇文章上,你可能想直接跳到答案

今天早上我发了一篇关于我的困惑的帖子

机器类型(C++ librairies):i386 vs x86_64

但我想我做错了不准确.所以我决定举一个我面对的情况的例子,我无法理解.

步骤1

我在机器A上构建了一个库,一个2岁的mac,OS x 10.7.5(我猜是64位;我的猜测基于你将在下面的附加信息中看到的命令)使用以下文件.

标题SimpleClass.hpp:

#ifndef SIMPLECLASS_HPP
#define SIMPLECLASS_HPP

class SimpleClass
{
public:
  SimpleClass();
  SimpleClass(const SimpleClass& orig);
  virtual ~SimpleClass();
private:

} ;

#endif  /* SIMPLECLASS_HPP */

源文件SimpleClass.cpp:

#include "SimpleClass.h"
#include 

SimpleClass::SimpleClass()
{
  std::cout << "A new instance of Simple Class was created" << std::endl;
}

SimpleClass::SimpleClass(const SimpleClass& orig)
{
}

SimpleClass::~SimpleClass()
{
}

我使用创建库

~/cpp_test$ clang++ -c -o SC.o -I SimpleClass.hpp SimpleClass.cpp

~/cpp_test$ ar rcs libtest_sc.a SC.o

机器A的其他信息:

~/cpp_test$ clang++ --version
Apple LLVM version 4.2 (clang-425.0.28) (based on LLVM 3.2svn)
Target: x86_64-apple-darwin11.4.2
~/cpp_test$ uname -m
x86_64
~/cpp_test$ uname -p
i386
~/cpp_test$ lipo -info libtest_sc.a 
input file libtest_sc.a is not a fat file
Non-fat file: libtest_sc.a is architecture: x86_64

第2步

我将SimpleClass.hpp以及库复制到另一台机器B,这是一台5年前使用osx 10.6.7的Mac机器,我认为它是32位.我编写以下hello文件来测试库

#include 
#include "SimpleClass.hpp"

int main()
{
  std::cout << "Hello World!" << std::endl;
  SimpleClass testObj;
  return 0;
} 

令人惊讶的是,我没有遇到与图书馆链接的问题.

[~/Downloads/Gmail-9]$ g++ -o hello -L. -ltest_sc hello.cpp
[~/Downloads/Gmail-9]$ ./hello
Hello World!
A new instance of Simple Class was created

机器B的其他信息:

[~/Downloads/Gmail-9]$ uname -m
i386
[~/Downloads/Gmail-9]$ uname -p
i386
[~/Downloads/Gmail-9]$ g++ --version
i686-apple-darwin10-g++-4.2.1 (GCC) 4.2.1 (Apple Inc. build 5666) (dot 3)
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

第3步

我在Machine C上使用相同的头文件和hello文件再次复制相同的库,这是一个10.9.2的新mac,我相信是64位.

令人惊讶的是我有链接问题

MacBook-Pro:testcpp$ g++ -o hello -L. -ltest_sc hello.cpp

Undefined symbols for architecture x86_64:
  "std::ostream::operator<<(std::ostream& (*)(std::ostream&))", referenced from:
      SimpleClass::SimpleClass() in libtest_sc.a(SC.o)
  "std::ios_base::Init::Init()", referenced from:
      ___cxx_global_var_init in libtest_sc.a(SC.o)
  "std::ios_base::Init::~Init()", referenced from:
      ___cxx_global_var_init in libtest_sc.a(SC.o)
  "std::cout", referenced from:
      SimpleClass::SimpleClass() in libtest_sc.a(SC.o)
  "std::basic_ostream >& std::endl >(std::basic_ostream >&)", referenced from:  
      SimpleClass::SimpleClass() in libtest_sc.a(SC.o)
  "std::basic_ostream >& std::operator<< >(std::basic_ostream >&, char const*)", referenced from:
      SimpleClass::SimpleClass() in libtest_sc.a(SC.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

关于机器C的其他信息

g++ --version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
Target: x86_64-apple-darwin13.1.0
Thread model: posix

MacBook-Pro:testcpp$ uname -m
x86_64
MacBook-Pro:testcpp$ uname -p
i386

我本以为机器B的连接问题是32位而不是机器C是64位,但我却反其道而行之.谁能解释一下我在这里缺少什么？

编辑(第4步)

在机器C上,当我向g++命令添加选项时-stdlib=libstdc++,"未定义符号"错误消失,可执行文件正确运行.运行G ++与-v让我注意到默认选项stdlib是libc++不libstdc++.因此,虽然机器A和机器C都是64位,但stdlib默认情况下它们不会使用相同的错误导致错误Undefined symbols for architecture x86_64.