undefined reference to `pthread_key_create' (linker error)

问题:

I have downloaded gtest 1.7.0 sources from here:

https://code.google.com/p/googletest/downloads/list

and build the gtest .a files (lib files) on ubuntu 13.10:

Linux ubuntu 3.11.0-15-generic #23-Ubuntu SMP Mon Dec 9 18:17:04 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux 

and the resulting lib is called: libgtest.a. In my main.cpp file Have:

#include <iostream> #include "gtest/gtest.h"  int main(){     std::cout << "Test \n";     int argc = 2;     char* cp01;     char* cp02;     char* argv[] = {cp01, cp02};     testing::InitGoogleTest(&argc, argv);     return 0; } 

From a terminal I build with:

g++ main.cpp -I/home/user/gtest-1.7.0/include -L/home/user/gtest-1.7.0/lib/.libs -lpthread -lgtest 

which gives the following errors:

/home/user/gtest-1.7.0/lib/.libs/libgtest.so: undefined reference to `pthread_key_create' /home/user/gtest-1.7.0/lib/.libs/libgtest.so: undefined reference to `pthread_getspecific' /home/user/gtest-1.7.0/lib/.libs/libgtest.so: undefined reference to `pthread_key_delete' /home/user/gtest-1.7.0/lib/.libs/libgtest.so: undefined reference to `pthread_setspecific' collect2: error: ld returned 1 exit status 

Based on this: error during making GTest

I have also tried -pthread instead of -lpthread but gives same error:

g++ main.cpp -I/home/user/gtest-1.7.0/include -L/home/user/gtest-1.7.0/lib/.libs -pthread -lgtest 

EDIT: I have also tried to specifying -pthread as the last argument:

g++ main.cpp -I/home/user/gtest-1.7.0/include -L/home/user/gtest-1.7.0/lib/.libs -lgtest -pthread 

same error What am I doing wrong?

回答1:

The option -lgtest is attempting to link the dynamic library libgtest.so. You wish to link the static library /home/user/gtest-1.7.0/lib/.libs/libgtest.a.

Instead of:

g++ main.cpp -I/home/user/gtest-1.7.0/include -L/home/user/gtest-1.7.0/lib/.libs -lgtest -pthread 

use:

g++ main.cpp -I/home/user/gtest-1.7.0/include /home/user/gtest-1.7.0/lib/.libs/libgtest.a -pthread 

Note that your commandline supplies no name for the resulting executable, which will default to a.out. If you want it called, e.g. mytest, then do:

g++ -o mytest main.cpp -I/home/user/gtest-1.7.0/include /home/user/gtest-1.7.0/lib/.libs/libgtest.a -pthread 

回答2:

You need to specify -pthread after -lgtest. The linker takes libraries in order, and only takes as much as it needs to resolve references which are undefined at that point.

回答3:

Nope, the problem is with Gtest's build.

If you build it using the standard configure approach, it isn't supplying the -lpthread correctly to create libgtest.so. Hence, when you try building a final shared library that actually uses the pthread capability it fails.

Instead, use the Cmake approach:

cd gtest-1.7.0 mkdir build cd build cmake -DBUILD_SHARED_LIBS=ON .. make  

And then manually install these into /usr/lib/

This version correctly links in libpthread into libgtest.

回答4:

Use -pthread instead of -lpthread (for linking with pthread-library), while you using gtest in your executable.

OR

Move the -lpthread after libgtest.a (sequence matters).

回答5:

To answer we probably need more information, are you on a 64 bit machine and downloaded a 32 bit library?

文章来源: undefined reference to `pthread_key_create' (linker error)