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Goal: I want to use thread STL of C++11 in Matlab mex file (R2013a) using Xcode 4.6

I modified ~/.matlab/R2013a/mexopts.sh

        CC='clang++'   # was llvm-gcc-4.2
        CXX='clang++'   # was llvm-g++-4.2
        MACOSX_DEPLOYMENT_TARGET='10.8'   # was 10.5. C++11 is supported >=10.7
        CXXFLAGS="$CXXFLAGS -std=gnu++11 -stdlib=libc++"   # additional flags

Normal mex files without C++11 features are compiled well. Further, STL is well detected by the compiler except linking failure.

>> mex mextest.cpp

Undefined symbols for architecture x86_64:
"std::__1::__thread_struct::__thread_struct()", referenced from:                                      
    void* std::__1::__thread_proxy<std::__1::tuple<void (*)()> >(void*) in mextest.o                        
"std::__1::__thread_struct::~__thread_struct()", referenced from:                            
    void* std::__1::__thread_proxy<std::__1::tuple<void (*)()> >(void*) in mextest.o                        
"std::__1::__thread_local_data()", referenced from:                              
    void* std::__1::__thread_proxy<std::__1::tuple<void (*)()> >(void*) in mextest.o                      
"std::__1::__throw_system_error(int, char const*)", referenced from:                      
    _mexFunction in mextest.o                   
"std::__1::thread::join()", referenced from:                    
    _mexFunction in mextest.o                            
"std::__1::thread::~thread()", referenced from:                    
    _mexFunction in mextest.o    
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

    mex: link of ' "mextest.mexmaci64"' failed.

Error using mex (line 206)
Unable to complete successfully.

The actual source code is shown below. The details are not important because it compiles well in Matlab R2013 WINDOWS version with Visual Studio 2012 Express. An equivalent cpp was also well compiled with "clang++ -std=gnu++11 -stdlib=libc++ clangtest.cpp". So, at least, there is no logical error in the codes (I'm not saying it is safe codes. It is just a test.)

#include "mex.h"
#include <thread>
#include <stdio.h>

int count_thread1 = 0;
int count_thread2 = 0;

void hello()
{
    count_thread2 = 0;
    for(int i=0; i<=10000; i++){
        for (int j=1;j<=20000;j++){
            count_thread2 = i-j-1;
        }
        count_thread2++;
        printf("2: %d , %d\n", count_thread1, count_thread2); // Not sure if printf is thread-safe in Matlab. But it works in this particular example
    }
}
void mexFunction(int nlhs,mxArray *plhs[],int nrhs,const mxArray *prhs[])
{
    count_thread1 = 0;
    std::thread t(hello);
    for (int i=1;i<=10000;i++)
    {
        for (int j=1;j<=20000;j++){
            count_thread1 = -i+j-1;
        }
        count_thread1++;
        mexPrintf("1: %d , %d\n", count_thread1, count_thread2);
    }
    mexPrintf("\n");
    t.join();
    mexPrintf("Done\n");
}

It seems like I have to replace some include directories and/or library directories. What kind of options should be modify?

Thank you.

4

1 回答 1

5

该错误是由于编译-stdlib=libc++但链接到-lstdc++. 您可以通过以下两种方式之一修复它：

  1. 修复它在mexopts.sh. 最激烈和最有效的解决方案。位于 中~/.matlab/${MATLAB_VERSION}/mexopts.sh，这决定了所有编译器选项。只需将所有 stdc++ 查找/替换为 c++。

  2. 拼凑解决方案：只需添加-lc++到CXXLIBS. 我不确定链接多个标准库版本的效果是什么，但它似乎有效。在您的 mex 调用中，添加参数CXXLIBS="\$CXXLIBS -lc++".

作为次要问题，我相信您完全覆盖了 ; 的值CXXFLAGS。您必须$像我上面对库所做的那样转义符号。

于 2013-09-03T23:11:49.353 回答