CMake find_package dependency on subproject

In executable's CMakeLists.txt you can check if you are building stand-alone or as part of project:

if( CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR )
  # stand-alone build
  find_package(static_lib1)
else()
  include_directories(../static_lib1)
  link_directories(../static_lib1)
  ...
  target_link_libraries(executable static_lib1)
endif()