CMake: set directory for target sources

Question

I have a C++ project where all implementation source files (*.cpp) reside in a src directory within the project directory. Some of the files are in further subdirectories. Let's say there are 50 files in src/foo/. I need to list these files as part of the add_library and/or the target_sources function.

Now, everywhere one looks, adding all files from a directory automtically is discouraged, which is fine with me. So I am going to list all the files manually; but repeating the common prefix src/foo/ 50 times seems really silly and is annoying.

In the documentation for target_sources it says

Relative source file paths are interpreted as being relative to the current source directory (i.e. CMAKE_CURRENT_SOURCE_DIR).

So I've added set(CMAKE_CURRENT_SOURCE_DIR "src/foo/") before the call to target_source but it didn't work. (I get a "Cannot find source file" error.)

So what is the correct way to achieve what I want if it is even possible?

N.B.: The (public) header files (*.hpp) of the project are in an include directory (outside of src). This is nicely configured (without having to list the individual files) with the target_include_directories function.

Answer 1

but repeating the common prefix src/foo/ 50 times

Just prepend the prefix to the sources.

set(target_sources
    source1.c
    source2.c
)
list(TRANSFORM target_sources PREPEND "src/foo/")