don't warn on GuardedBy self reference

Reviewed By: sblackshear

Differential Revision: D4015092

fbshipit-source-id: 7a82710

infer/src/backend/rearrange.ml

@@ -744,6 +744,9 @@ let add_guarded_by_constraints tenv prop lexp pdesc =
           | Sil.Apred (Alocked, _) -> true
           | _ -> false)
         (Attribute.get_for_exp tenv prop guarded_by_exp) in
+    let guardedby_is_self_referential =
+      string_equal "itself" (String.lowercase guarded_by_str) ||
+      string_is_suffix guarded_by_str (Ident.fieldname_to_string accessed_fld) in
     let should_warn pdesc =
       (* adding this check implements "by reference" semantics for guarded-by rather than "by value"
          semantics. if this access is through a local L or field V.f
@@ -767,7 +770,8 @@ let add_guarded_by_constraints tenv prop lexp pdesc =
       Cfg.Procdesc.get_access pdesc <> PredSymb.Private &&
       not (Annotations.pdesc_has_annot pdesc Annotations.visibleForTesting) &&
       not (Procname.java_is_access_method (Cfg.Procdesc.get_proc_name pdesc)) &&
-      not (is_accessible_through_local_ref lexp) in
+      not (is_accessible_through_local_ref lexp) &&
+      not guardedby_is_self_referential in
     match find_guarded_by_exp guarded_by_str prop.Prop.sigma with
     | Some (Sil.Eexp (guarded_by_exp, _), typ) ->
         if is_read_write_lock typ

infer/tests/codetoanalyze/java/infer/GuardedByExample.java

@@ -370,4 +370,36 @@ public class GuardedByExample {
     }
   }
 
+ @GuardedBy("self_reference")
+ Object self_reference;
+
+ void guardedBySelfReferenceOK() {
+    synchronized(self_reference){
+       this.self_reference.toString();
+    }
+  }
+
+  // TODO: report on this case, or at least a version which writes
+  /*
+ void guardedBySelfReferenceBad() {
+    this.self_reference.toString();
+  }
+  */
+
+  @GuardedBy("itself")
+  Object itself_fld;
+
+ void itselfOK() {
+    synchronized(itself_fld){
+     this.itself_fld.toString();
+    }
+  }
+
+  // TODO: report on this case, or at least a version which writes
+  /*
+ void itselfBad() {
+    this.itself_fld.toString();
+  }
+  */
+
 }