[CMake] Accessing source directory of a target

[Robert Dailey]

Hello,

Is there a SOURCE_DIR property for targets? I wasn't able to find
anything in the documentation on this, however I thought I saw
something similar to this a few years ago. I'm using CMake 3.2.
Basically I want the equivalent of CMAKE_CURRENT_SOURCE_DIR, but for a
specific project.

Documentation states you can do <TARGET>_SOURCE_DIR, but this value is
empty for me. Unless this is for projects, not targets (i.e. the value
passed to the project() command).

Thanks in advance.