The options that I found were to:
- Add a reference to PostSharp in Project A.
- Add dummy code in Project B so that the compiler would detect that the reference is being used.
- Add a build event to force copy the DLL.
I don’t like any of the above solutions. They are hacks in my opinion and will only make for a more unmaintainable solution in the long run.
I have fixed the problem by using a common output directory. This seems to be a recommended solution by many. I have also experienced much faster build times. See this Stackoverflow post.