pthreads - cmake and libpthread

Question

I'm running RHEL 5.1 and use gcc.

How I tell cmake to add -pthread to compilation and linking?

Answer 1

@Manuel was part way there. You can add the compiler option as well, like this:

If you have CMake 3.1.0+, this becomes even easier:

set(THREADS_PREFER_PTHREAD_FLAG ON)
find_package(Threads REQUIRED)
target_link_libraries(my_app PRIVATE Threads::Threads)

If you are using CMake 2.8.12+, you can simplify this to:

find_package(Threads REQUIRED)
if(THREADS_HAVE_PTHREAD_ARG)
  target_compile_options(my_app PUBLIC "-pthread")
endif()
if(CMAKE_THREAD_LIBS_INIT)
  target_link_libraries(my_app "${CMAKE_THREAD_LIBS_INIT}")
endif()

Older CMake versions may require:

find_package(Threads REQUIRED)
if(THREADS_HAVE_PTHREAD_ARG)
  set_property(TARGET my_app PROPERTY COMPILE_OPTIONS "-pthread")
  set_property(TARGET my_app PROPERTY INTERFACE_COMPILE_OPTIONS "-pthread")
endif()
if(CMAKE_THREAD_LIBS_INIT)
  target_link_libraries(my_app "${CMAKE_THREAD_LIBS_INIT}")
endif()

If you want to use one of the first two methods with CMake 3.1+, you will need set(THREADS_PREFER_PTHREAD_FLAG ON) there too.