add correct rpath settings (for macos)

Created by: gaede

• see (LCIO PR#121)

BEGINRELEASENOTES

• replace ilcsoft_default_rpath_settings.cmake with the one from LCIO
  • see https://github.com/iLCSoft/LCIO/pull/121
• this fixes the rpath settings for all iLCSoft tools using this script to work on MacOS
• (needed to install the key4hep stack on darwin)

ENDRELEASENOTES

cmakemodules/ilcsoft_default_rpath_settings.cmake

-
- # rpath treatment for macos: always use rpath:
- # ( maybe we should also use this on other platforms ?)
- if (APPLE)
-   # use, i.e. don't skip the full RPATH for the build tree
-   SET(CMAKE_SKIP_BUILD_RPATH  FALSE)
-
-   # when building, don't use the install RPATH already
-   # (but later on when installing)
-   SET(CMAKE_BUILD_WITH_INSTALL_RPATH FALSE)
-
-   SET(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib")
-
-   # add the automatically determined parts of the RPATH
-   # which point to directories outside the build tree to the install RPATH
-   SET(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)
-
-   # the RPATH to be used when installing, but only if it's not a system directory
-   LIST(FIND CMAKE_PLATFORM_IMPLICIT_LINK_DIRECTORIES "${CMAKE_INSTALL_PREFIX}/lib" isSystemDir)
-   IF("${isSystemDir}" STREQUAL "-1")
-     SET(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib")
-   ENDIF("${isSystemDir}" STREQUAL "-1")
-
+#---RPATH options-------------------------------------------------------------------------------
+#  When building, don't use the install RPATH already (but later on when installing)
+set(CMAKE_SKIP_BUILD_RPATH FALSE)         # don't skip the full RPATH for the build tree
+set(CMAKE_BUILD_WITH_INSTALL_RPATH FALSE) # use always the build RPATH for the build tree
+set(CMAKE_MACOSX_RPATH TRUE)              # use RPATH for MacOSX
+set(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE) # point to directories outside the build tree to the install RPATH
+
+# Check whether to add RPATH to the installation (the build tree always has the RPATH enabled)
+if(APPLE)
+  set(CMAKE_INSTALL_NAME_DIR "@rpath")
+  set(CMAKE_INSTALL_RPATH "@loader_path/../${CMAKE_INSTALL_LIBDIR}")    # self relative LIBDIR
+  # the RPATH to be used when installing, but only if it's not a system directory
+  list(FIND CMAKE_PLATFORM_IMPLICIT_LINK_DIRECTORIES "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}" isSystemDir)
+  if("${isSystemDir}" STREQUAL "-1")
+    set(CMAKE_INSTALL_RPATH "@loader_path/../${CMAKE_INSTALL_LIBDIR}")
+  endif("${isSystemDir}" STREQUAL "-1")
 else()
-
-   # add library install path to the rpath list
-   SET( CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib" )
-   MARK_AS_ADVANCED( CMAKE_INSTALL_RPATH )
-
-   # append link pathes to rpath list
-   SET( CMAKE_INSTALL_RPATH_USE_LINK_PATH 1 )
-   MARK_AS_ADVANCED( CMAKE_INSTALL_RPATH_USE_LINK_PATH )
-
+  set(CMAKE_SKIP_INSTALL_RPATH TRUE)           # skip the full RPATH for the install tree
 endif()