I have a C++ file in a project that uses multithreading and I can’t compile it without adding the compiler flag “-pthread”. I am compiling using CMake and want to add the flag for only this one file.

The “setup” is:
add_executable(someClass thisClass.cpp)

The one solution that works is set(CMAKE_CXX_FLAGS “${CMAKE_CXX_FLAGS} -pthread”) but I understand this is bad practice.

Other things I have seen and tried that didn’t work are:
target_compile_options(someClass PRIVATE -pthread)
set_target_properties(someClass PROPERTIES COMPILE_OPTIONS -pthread)

I am not super familar with CMake so I don’t know if quotations actually do much but I have also tried adding quotations around -pthread.
For these other solutions, I know they don’t work because the build fails and because I run it with
make VERBOSE=1 and don’t see the flag being passed to the compiler.

Thanks for your time and help!