[IR] utility function for detecting when Var appears in source code

Summary:
We frequently want to treat such vars differently than true program variables.

Used in only one place now, but will be used in a successor.

Reviewed By: mbouaziz, jvillard

Differential Revision: D7067882

fbshipit-source-id: 90e0348

infer/src/absint/Var.ml

@@ -29,6 +29,12 @@ let is_return = function ProgramVar pvar -> Pvar.is_return pvar | LogicalVar _ -
 
 let is_footprint = function ProgramVar _ -> false | LogicalVar id -> Ident.is_footprint id
 
+let appears_in_source_code = function
+  | LogicalVar _ ->
+      false
+  | ProgramVar pvar ->
+      not (Pvar.is_frontend_tmp pvar)
+
 let pp fmt = function ProgramVar pv -> Pvar.pp Pp.text fmt pv | LogicalVar id -> Ident.pp fmt id
 
 let get_footprint_index t =

infer/src/absint/Var.mli

@@ -30,6 +30,10 @@ val is_return : t -> bool
 
 val is_footprint : t -> bool
 
+val appears_in_source_code : t -> bool
+(** return true if this variable appears in source code (i.e., is not a LogicalVar or a
+    frontend-generated ProgramVar) *)
+
 val get_footprint_index : t -> int option
 
 val pp : Format.formatter -> t -> unit

infer/src/concurrency/RacerD.ml

@@ -1014,12 +1014,8 @@ let report_thread_safety_violation tenv pdesc ~make_description ~report_kind acc
     let is_full_trace = TraceElem.is_direct final_sink in
     let is_pvar_base initial_sink =
       let access_path = Access.get_access_path (PathDomain.Sink.kind initial_sink) in
-      Option.value_map ~default:false access_path ~f:(fun ap ->
-          match ap with
-          | (Var.LogicalVar _, _), _ ->
-              false
-          | (Var.ProgramVar pvar, _), _ ->
-              not (Pvar.is_frontend_tmp pvar) )
+      Option.value_map ~default:false access_path ~f:(fun ((var, _), _) ->
+          Var.appears_in_source_code var )
     in
     (* Traces can be truncated due to limitations of our Buck integration. If we have a truncated
        trace, it's probably going to be too confusing to be actionable. Skip it.