Cmake find module to distinguish shared or static

I have a cmake c++ project that uses libCrypto++. I have FindCryptoPP.cmake module hosted here. Important parts are:

find_library(CryptoPP_LIBRARY
  NAMES cryptopp
  DOC "CryptoPP library"
  NO_PACKAGE_ROOT_PATH
  PATHS "/usr/lib/x86_64-linux-gnu/"
)
...
add_library(CryptoPP::CryptoPP UNKNOWN IMPORTED)
set_target_properties(CryptoPP::CryptoPP PROPERTIES
    IMPORTED_LOCATION "${CryptoPP_LIBRARY}"
    INTERFACE_INCLUDE_DIRECTORIES "${CryptoPP_INCLUDE_DIR}")

And this works fine, finds static library file (*.a). Now I would like to create separate targets CryptoPP::CryptoPP-static and CryptoPP::CryptoPP-shared. Necessary files are installed (default ubuntu install):

/usr/lib/x86_64-linux-gnu/libcryptopp.a
/usr/lib/x86_64-linux-gnu/libcryptopp.so

I want to know how to tell find_library to search either static or shared version (preferably in portable way - I need all of Linux, Windows, MacOS) and specify the type created target.

Actually CMake's default is to search first for shared libraries and then for static libraries.

The key is the order of values in the CMAKE_FIND_LIBRARY_SUFFIXES global variable, which is e.g. set in CMakeGenericSystem.cmake as part of CMake's compiler/platform detection of the project() command to:

set(CMAKE_FIND_LIBRARY_SUFFIXES ".so" ".a")

For a solution take a look at an existing find module like FindBoost.cmake:

# Support preference of static libs by adjusting CMAKE_FIND_LIBRARY_SUFFIXES
if( Boost_USE_STATIC_LIBS )
  set( _boost_ORIG_CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES})
  if(WIN32)
    list(INSERT CMAKE_FIND_LIBRARY_SUFFIXES 0 .lib .a)
  else()
    set(CMAKE_FIND_LIBRARY_SUFFIXES .a)
  endif()
endif()

Here the CMAKE_FIND_LIBRARY_SUFFIXES variable is temporarily changed for the find_library() calls.

Same should be applicable here. Just be aware the find_library() does cache its results if you want to do the same search twice.