Undefined reference to pthread_getspecific
In the last two post1 post2 I tried to setup a working cross-compilation environment for Beaglebone. While I was trying out a test program, I noticed that I was not able to compile a program if I link it with gtest
I was getting a linking error which was not able to find references to pthread_getspecific and pthread_setspecific.
If you are encountering an undefined reference to pthread_getspecific error while linking your C++ program with the Google Test (gtest) library, it is likely that your program is not linking with the pthread library.
Linking with pthread to solve the error
The pthread library is a library that provides support for multithreaded programming in C and C++. It is a requirement for using the gtest library because gtest uses pthread for thread synchronization.
To fix the error, you should add the -pthread flag to your linker options. This will link your program with the pthread library and resolve the undefined reference error.
target_link_libraries(${project_name} PUBLIC fmt::fmt GTest::gtest GTest::gtest_main -pthread)
Compiling gtest with proper flags
When you provide -DBUILD_SHARED_LIBS=ON option while running CMake, it specifies that you want to build the project as a shared library. This means that the code will be compiled into a shared object file (.so) that can be dynamically linked by other programs at runtime.
So the above problem can also be solved by providing the -DBUILD_SHARED_LIBS while doing cmake
cd build
cmake -DBUILD_SHARED_LIBS=ON ..
make
sudo make install