cmake_minimum_required(VERSION 3.11)

project(Foo)

file(WRITE dir1/CMakeLists.txt [[
    add_library(foobar INTERFACE)
    target_include_directories(foobar INTERFACE foo-bar)

    add_library(Foo::Bar ALIAS foobar)
]])

add_subdirectory(dir1)

file(WRITE baz.cpp "int main() {}")

add_executable(baz baz.cpp)
target_link_libraries(baz PRIVATE Foo::Bar)