cmake_minimum_required(VERSION 3.9) # can be lowered

project(cmake-follow-symlinks-at-install LANGUAGES NONE)

# Setup a test case:
# +---------------------------------------+
# | symdir/                               |
# |     foo.lib.0 -> ../libdir/foo.lib    |
# |     foo.lib.1 -> ../libdir/foo.lib    |
# |     bar.lib.0 -> ../libdir/bar.lib    |
# |     bar.lib.1 -> ../libdir/bar.lib    |
# | libdir/                               |
# |     foo.lib                           |
# |     bar.lib                           |
# +---------------------------------------+
execute_process(COMMAND ${CMAKE_COMMAND} -E make_directory "symdir")
execute_process(COMMAND ${CMAKE_COMMAND} -E make_directory "libdir")
foreach(mylib IN ITEMS "foo.lib" "bar.lib")
        execute_process(COMMAND ${CMAKE_COMMAND} -E touch "libdir/${mylib}")
        foreach(num RANGE 1)
                execute_process(COMMAND ${CMAKE_COMMAND} -E touch "symdir/${mylib}.${num}")
                execute_process(COMMAND ${CMAKE_COMMAND} -E create_symlink "${CMAKE_CURRENT_SOURCE_DIR}/libdir/${mylib}" "${CMAKE_CURRENT_SOURCE_DIR}/symdir/${mylib}.${num}")
        endforeach()
endforeach()

# Install all files from symdir and resolve their symlinks
file(GLOB symdir_contents RELATIVE "${CMAKE_CURRENT_SOURCE_DIR}" "symdir/*")
foreach(mylib IN LISTS symdir_contents)
        get_filename_component(fpath "${mylib}" REALPATH)
        install(FILES "${fpath}" DESTINATION "$ENV{HOME}/tmp")
endforeach()

# Result:
# +---------------------------------------+
# | -- Installing: /home/l2y/tmp/bar.lib  |
# | -- Up-to-date: /home/l2y/tmp/bar.lib  |
# | -- Installing: /home/l2y/tmp/foo.lib  |
# | -- Up-to-date: /home/l2y/tmp/foo.lib  |
# +---------------------------------------+