LATTE.cmake: create and use imported target

cmake/Modules/FindLATTE.cmake

@@ -7,12 +7,21 @@
 
 find_library(LATTE_LIBRARY NAMES latte)
 
-set(LATTE_LIBRARIES ${LATTE_LIBRARY})
-
 include(FindPackageHandleStandardArgs)
 # handle the QUIETLY and REQUIRED arguments and set LATTE_FOUND to TRUE
 # if all listed variables are TRUE
 
 find_package_handle_standard_args(LATTE DEFAULT_MSG LATTE_LIBRARY)
 
+# Copy the results to the output variables and target.
+if(LATTE_FOUND)
+  set(LATTE_LIBRARIES ${LATTE_LIBRARY})
+
+  if(NOT TARGET LATTE::latte)
+    add_library(LATTE::latte UNKNOWN IMPORTED)
+    set_target_properties(LATTE::latte PROPERTIES
+      IMPORTED_LOCATION "${LATTE_LIBRARY}")
+  endif()
+endif()
+
 mark_as_advanced(LATTE_LIBRARY)

cmake/Modules/Packages/LATTE.cmake

@@ -26,15 +26,15 @@ if(PKG_LATTE)
     )
     add_dependencies(lammps latte_build)
     ExternalProject_get_property(latte_build INSTALL_DIR)
-    set(LATTE_LIBRARIES ${INSTALL_DIR}/${_LATTE_LIBDIR}/liblatte.a)
+    target_link_libraries(lammps PRIVATE ${INSTALL_DIR}/${_LATTE_LIBDIR}/liblatte.a ${LAPACK_LIBRARIES})
+    if(NOT LAPACK_FOUND)
+      add_dependencies(latte_build linalg)
+    endif()
   else()
     find_package(LATTE)
     if(NOT LATTE_FOUND)
       message(FATAL_ERROR "LATTE library not found, help CMake to find it by setting LATTE_LIBRARY, or set DOWNLOAD_LATTE=ON to download it")
     endif()
+    target_link_libraries(lammps PRIVATE LATTE::latte)
   endif()
-  if(NOT LAPACK_FOUND)
-    add_dependencies(latte_build linalg)
-  endif()
-  target_link_libraries(lammps PRIVATE ${LATTE_LIBRARIES} ${LAPACK_LIBRARIES})
 endif()