[starvation] determine lock recursiveness on language if type unknown

Summary: Sometimes the type definition is missing, especially in not-well supported build systems. When missing, default to true if on Java since you'd have to explicitly select a non-recursive one on purpose, and vice versa for clang.

Reviewed By: jvillard

Differential Revision: D28745172

fbshipit-source-id: 8b0e26e1a

infer/src/concurrency/starvationDomain.ml

@@ -128,15 +128,21 @@ module Lock = struct
 
 
   let is_recursive tenv lock =
-    let is_class_and_recursive_lock = function
-      | {Typ.desc= Tptr ({desc= Tstruct name}, _)} | {desc= Tstruct name} ->
-          ConcurrencyModels.is_recursive_lock_type name
-      | typ ->
-          L.debug Analysis Verbose "Asked if non-struct type %a is a recursive lock type.@."
-            (Typ.pp_full Pp.text) typ ;
-          true
-    in
-    get_typ tenv lock |> Option.exists ~f:is_class_and_recursive_lock
+    (* The "default" below is returned when we don't have enough information. We choose
+       the default depending on the language, since most Java locks are recursive and most C++ locks
+       are not. *)
+    match get_typ tenv lock with
+    | Some {Typ.desc= Tptr ({desc= Tstruct name}, _)} | Some {desc= Tstruct name} ->
+        ConcurrencyModels.is_recursive_lock_type name
+    | Some typ ->
+        (* weird type passed as a lock, return default *)
+        L.debug Analysis Verbose "Asked if non-struct type %a is a recursive lock type.@\n"
+          (Typ.pp_full Pp.text) typ ;
+        Language.curr_language_is Java
+    | None ->
+        (* could not find type definition, return default *)
+        L.debug Analysis Verbose "Could not resolve type for lock %a.@\n" pp lock ;
+        Language.curr_language_is Java
 end
 
 module AccessExpressionDomain = struct