fix up cmake lokimq target

CMakeLists.txt

@@ -78,6 +78,7 @@ include(cmake/target_link_libraries_system.cmake)
 include(cmake/add_import_library.cmake)
 include(cmake/add_log_tag.cmake)
 include(cmake/libatomic.cmake)
+include(cmake/link_dep_libs.cmake)
 
 if (STATIC_LINK)
   set(CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_STATIC_LIBRARY_SUFFIX})
@@ -148,10 +149,14 @@ endif()
 
 option(FORCE_LOKIMQ_SUBMODULE "force using lokimq submodule" OFF)
 if(NOT FORCE_LOKIMQ_SUBMODULE)
-  find_package(LokiMQ 1.2)
-endif()
-if(LokiMQ_FOUND)
-  message(STATUS "using system lokimq")
+  pkg_check_modules(LOKIMQ liblokimq>=1.2)
+endif()
+if(LOKIMQ_FOUND)
+  add_library(lokimq INTERFACE)
+  link_dep_libs(lokimq INTERFACE "${LOKIMQ_LIBRARY_DIRS}" ${LOKIMQ_LIBRARIES})
+  target_include_directories(lokimq INTERFACE ${LOKIMQ_INCLUDE_DIRS})
+  add_library(lokimq::lokimq ALIAS lokimq)
+  message(STATUS "Found system liblokimq ${LOKIMQ_VERSION}")
 else()
   message(STATUS "using lokimq submodule")
   add_subdirectory(${CMAKE_SOURCE_DIR}/external/loki-mq)

cmake/FindLokiMQ.cmake

@@ -1,21 +0,0 @@
-find_package(PkgConfig)
-if (PKG_CONFIG_FOUND)
-  pkg_check_modules(PC_LOKIMQ QUIET liblokimq>=${LokiMQ_VERSION})
-endif()
-
-find_path(LOKIMQ_INCLUDE_DIR lokimq/lokimq.h
-  HINTS ${PC_LOKIMQ_INCLUDEDIR} ${PC_LOKIMQ_INCLUDE_DIRS})
-
-find_library(LOKIMQ_LIBRARY NAMES lokimq
-  HINTS ${PC_LOKIMQ_LIBDIR} ${PC_LOKIMQ_LIBRARY_DIRS})
-
-mark_as_advanced(LOKIMQ_INCLUDE_DIR LOKIMQ_LIBRARY)
-
-set(LOKIMQ_LIBRARIES ${LOKIMQ_LIBRARY} ${PC_LOKIMQ_LIBRARIES})
-set(LOKIMQ_INCLUDE_DIRS ${LOKIMQ_INCLUDE_DIR})
-
-include(FindPackageHandleStandardArgs)
-find_package_handle_standard_args(LokiMQ DEFAULT_MSG
-                                  LOKIMQ_LIBRARY LOKIMQ_INCLUDE_DIR)
-
-mark_as_advanced(LOKIMQ_INCLUDE_DIR LOKIMQ_LIBRARY)

cmake/link_dep_libs.cmake

@@ -0,0 +1,13 @@
+# Properly links a target to a list of library names by finding the given libraries.  Takes:
+# - a target
+# - a linktype (e.g. INTERFACE, PUBLIC, PRIVATE)
+# - a library search path (or "" for defaults)
+# - any number of library names
+function(link_dep_libs target linktype libdirs)
+  foreach(lib ${ARGN})
+    find_library(link_lib-${lib} NAMES ${lib} PATHS ${libdirs})
+    if(link_lib-${lib})
+      target_link_libraries(${target} ${linktype} ${link_lib-${lib}})
+    endif()
+  endforeach()   
+endfunction()