title: CMake find_package for non-standard locations
body: <p>I am trying to make a self contained library whose dependencies are self contained.All installs are installed to &lt;repo_dir&gt;/libs//build.
  To find dependencies in cmake build system I use find_package. Because all installs are in a custom location I point I use HINTS to help out like so -</p>
  <pre><code># CMake 3.16.3
  # ../lib/Catch2/build is where Catch2Config.cmake is located
  find_package(Catch2 REQUIRED HINTS &quot;../lib/Catch2/build&quot; NO_MODULE)
  include_directories(tests)
  add_executable(tests tests.cpp)
  target_link_libraries(tests PRIVATE project_warnings project_options Catch2::Catch2)
  </code></pre>
  <p>I recognize that Catch2 likely doesn't need this as it is header only, however I am trying to learn what cmake is doing.
  The CMakeLists.txt above prints out</p>
  <pre><code>include could not find load file:                                                                                                   
      &lt;repo_dir&gt;/lib/Catch2/build/Catch2Targets.cmake                                                   │
  Call Stack (most recent call first):                                                                                                  
    tests/CMakeLists.txt:1 (find_package)
  </code></pre>
  <p>It looks like a target file is needed as well. I cannot find one in the Catch2 repo.
  I am also trying the same process for <a href="https://github.com/facebook/folly" rel="nofollow noreferrer">folly</a>, however it does not work for me either.
  Using the following in module mode for Boost worked. Why does it work?</p>
  <pre><code>set(CMAKE_INCLUDE_PATH ${CMAKE_INCLUDE_PATH} &quot;${PROJECT_SOURCE_DIR}/lib/boost_1_75_0/&quot;)
  set(CMAKE_LIBRARY_PATH ${CMAKE_LIBRARY_PATH} &quot;${PROJECT_SOURCE_DIR}/lib/boost_1_75_0/libs&quot;)
  find_package(Boost 1.60.0 REQUIRED)
  include_directories(${Boost_INCLUDE_DIRS})
  target_link_libraries(${CMAKE_PROJECT_NAME} ${Boost_LIBRARIES})
  </code></pre>
  <p>Could someone help to uncover my problems and how I should go about using</p>
  <ol>
  <li>Header only libraries</li>
  <li>Static lib binaries</li>
  <li>Self-Compiled Libraries</li>
  </ol>
  <p>Whose resources are in unusual places?</p>