CMAKE add sub-directory which is not sub-directory on real directory

Question

Is It possible to include sibling directory as Sub-Directory inside cmake ?

Something like

A 
  CMakeLists.txt

B
  CMakeLists.txt

Answer 1

Unfortunately, no.

As solution i may suggest you to add_subdirectory(A) and add_subdirectory(B) at the top level and set vars you want to export from A with PARENT_SCOPE. This would allow B/CMakeLists.txt to access varibles defined in A/CMakeLists.txt