Update rpath settings in line with DD4hep

CMakeLists.txt

@@ -57,6 +57,8 @@ configure_file (
 
 LIST( APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake )
 
+option(LCIO_SET_RPATH   "Link libraries with built-in RPATH (run-time search path)" ON)
+
 #FIND_PACKAGE( ILCUTIL COMPONENTS ILCSOFT_CMAKE_MODULES REQUIRED )
 
 # load default settings from ILCSOFT_CMAKE_MODULES

cmake/ilcsoft_default_rpath_settings.cmake

@@ -1,14 +1,27 @@
+#---RPATH options-------------------------------------------------------------------------------
 #  When building, don't use the install RPATH already (but later on when installing)
 set(CMAKE_SKIP_BUILD_RPATH FALSE)         # don't skip the full RPATH for the build tree
 set(CMAKE_BUILD_WITH_INSTALL_RPATH FALSE) # use always the build RPATH for the build tree
 set(CMAKE_MACOSX_RPATH TRUE)              # use RPATH for MacOSX
 set(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE) # point to directories outside the build tree to the install RPATH
 
-set(CMAKE_INSTALL_RPATH ${CMAKE_INSTALL_FULL_LIBDIR}) # install LIBDIR
-set(CMAKE_SKIP_INSTALL_RPATH FALSE)          # don't skip the full RPATH for the install tree
+# Check whether to add RPATH to the installation (the build tree always has the RPATH enabled)
 if(APPLE)
   set(CMAKE_INSTALL_NAME_DIR "@rpath")
   set(CMAKE_INSTALL_RPATH "@loader_path/../lib")    # self relative LIBDIR
-  set(CMAKE_SKIP_INSTALL_RPATH FALSE)          # don't skip the full RPATH for the install tree
+  # the RPATH to be used when installing, but only if it's not a system directory
+  list(FIND CMAKE_PLATFORM_IMPLICIT_LINK_DIRECTORIES "${CMAKE_INSTALL_PREFIX}/lib" isSystemDir)
+  if("${isSystemDir}" STREQUAL "-1")
+    set(CMAKE_INSTALL_RPATH "@loader_path/../lib")
+  endif("${isSystemDir}" STREQUAL "-1")
+elseif(LCIO_SET_RPATH)
+  set(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib") # install LIBDIR
+  # the RPATH to be used when installing, but only if it's not a system directory
+  list(FIND CMAKE_PLATFORM_IMPLICIT_LINK_DIRECTORIES "${CMAKE_INSTALL_PREFIX}/lib" isSystemDir)
+  if("${isSystemDir}" STREQUAL "-1")
+    set(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib")
+  endif("${isSystemDir}" STREQUAL "-1")
+else()
+  set(CMAKE_SKIP_INSTALL_RPATH TRUE)           # skip the full RPATH for the install tree
 endif()