design/build-system.md

@@ -64,6 +64,8 @@ malleable.
   be broken.  GHC will probably say "compilation IS NOT required" for
   most modules anyway.
 
+- The build system should report clearly at configure-time the status of each optional feature (e.g. editline support).
+
 ## Basic plan
 
 - Use our own build system for the work of actually building packages