How to create a cmake header-only library that depends on external header files?

Question

I have a project with the following file structure:

project
 |
 |-------> lib1
 |           |----> lib1.h
 |
 |-------> lib2
 |           |---->          


        

Answer 1

This problem was due to full path issue of INTERFACE library files, which got fixed in cmake version 3.13.

For more info: https://gitlab.kitware.com/cmake/cmake/issues/17556

This page also contains an example for better understanding.