Change how installation location is detected, as per Quentin's suggestion.

CMakeLists.txt

@@ -188,31 +188,35 @@ endif ()
 #
 
 
-set(GNUSTEP_LOCAL_ROOT  "$ENV{GNUSTEP_LOCAL_ROOT}")
-set(GNUSTEP_SYSTEM_ROOT "$ENV{GNUSTEP_SYSTEM_ROOT}")
+EXEC_PROGRAM(gnustep-config
+	ARGS "--installation-domain-for=libobjc2"
+	OUTPUT_VARIABLE DEFAULT_INSTALL_TYPE)
+
+
 # If we have GNUstep environment variables, then default to installing in the
 # GNUstep local environment.
-if (GNUSTEP_LOCAL_ROOT)
-	set(DEFAULT_INSTALL_TYPE "Local")
+if (DEFAULT_INSTALL_TYPE)
 else ()
-	set(DEFAULT_INSTALL_TYPE "None")
+	set(DEFAULT_INSTALL_TYPE "NONE")
 endif ()
 set(GNUSTEP_INSTALL_TYPE ${DEFAULT_INSTALL_TYPE} CACHE STRING
-	"GNUstep installation type.  Options are None, System or Local.")
-
-if (${GNUSTEP_INSTALL_TYPE} STREQUAL "System")
-	SET(LIB_INSTALL_PATH "${GNUSTEP_SYSTEM_ROOT}/Library/Libraries")
-	SET(HEADER_INSTALL_PATH "${GNUSTEP_SYSTEM_ROOT}/Library/Headers/objc")
-elseif (${GNUSTEP_INSTALL_TYPE} STREQUAL "Local")
-	SET(LIB_INSTALL_PATH "${GNUSTEP_LOCAL_ROOT}/Library/Libraries")
-	SET(HEADER_INSTALL_PATH "${GNUSTEP_LOCAL_ROOT}/Library/Headers/objc")
-else ()
+	"GNUstep installation type.  Options are NONE, SYSTEM, NETWORK or LOCAL.")
+
+if (${GNUSTEP_INSTALL_TYPE} STREQUAL "NONE")
 	SET(LIB_INSTALL_PATH lib)
-	SET(HEADER_INSTALL_PATH "include/objc")
+	SET(HEADER_INSTALL_PATH "include")
+else ()
+	EXEC_PROGRAM(gnustep-config
+		ARGS "--variable=GNUSTEP_${GNUSTEP_INSTALL_TYPE}_LIBRARIES"
+		OUTPUT_VARIABLE LIB_INSTALL_PATH)
+	EXEC_PROGRAM(gnustep-config
+		ARGS "--variable=GNUSTEP_${GNUSTEP_INSTALL_TYPE}_HEADERS"
+		OUTPUT_VARIABLE HEADER_INSTALL_PATH)
+else ()
 elseif (${GNUSTEP_INSTALL_TYPE} EQUAL "Local")
 endif ()
 
 install(TARGETS objc
 	LIBRARY DESTINATION ${LIB_INSTALL_PATH}
 	ARCHIVE DESTINATION ${LIB_INSTALL_PATH}
-	PUBLIC_HEADER DESTINATION ${HEADER_INSTALL_PATH})
+	PUBLIC_HEADER DESTINATION "${HEADER_INSTALL_PATH}/objc")