Callbacks, cleanup 2: some lazyness

Summary: Only RacerD uses the Cluster callbacks but we used to compute a lot of things anyway.

Reviewed By: sblackshear

Differential Revision: D7516279

fbshipit-source-id: 22f2b86

infer/src/backend/callbacks.ml

@@ -46,8 +46,11 @@ let register_cluster_callback language (callback: cluster_callback_t) =
 
 (** Collect what we need to know about a procedure for the analysis. *)
 let get_procedure_definition exe_env proc_name =
+  Option.map
+    ~f:(fun proc_desc ->
       let tenv = Exe_env.get_tenv exe_env proc_name in
-  Option.map ~f:(fun proc_desc -> (tenv, proc_desc)) (Exe_env.get_proc_desc exe_env proc_name)
+      (tenv, proc_desc) )
+    (Exe_env.get_proc_desc exe_env proc_name)
 
 
 let get_language proc_name =
@@ -78,6 +81,7 @@ let iterate_procedure_callbacks get_proc_desc exe_env summary proc_desc =
 
 (** Invoke all registered cluster callbacks on a cluster of procedures. *)
 let iterate_cluster_callbacks all_procs exe_env get_proc_desc =
+  if !cluster_callbacks <> [] then
     let procedures = List.filter_map ~f:(get_procedure_definition exe_env) all_procs in
     let environment = {procedures; get_proc_desc} in
     let language_matches language =