[report] restore missing "could be null and is dereferenced" message for nullable dereference

Summary:
We get messages like " object returned by `getArguments()` at line 101."
instead of " object returned by `getArguments()` could be null and is
dereferenced at line 101.". Tracking it down, it happens for
nullable-looking values, but I don't know why.

It seems that something regressed but I couldn't track it down.

So, just generate the error message in the same way as for non-nullable
objects in this case to fix the non-sensical message.

Reviewed By: jeremydubreil

Differential Revision: D14972325

fbshipit-source-id: 2a97501cc

infer/src/IR/Localise.ml

@@ -195,9 +195,7 @@ let access_str_empty proc_name_opt =
 let deref_str_nullable proc_name_opt nullable_obj_str =
   let tags = Tags.create () in
   Tags.update tags Tags.nullable_src nullable_obj_str ;
-  (* to be completed once we know if the deref'd expression is directly or transitively @Nullable*)
+  deref_str_null proc_name_opt
-  let problem_str = "" in
-  deref_str_null_ proc_name_opt problem_str
 
 
 (** dereference strings for null dereference due to weak captured variable in block *)

infer/src/biabduction/Rearrange.ml

@@ -1566,11 +1566,15 @@ let is_only_pt_by_fld_or_param_nonnull pdesc tenv prop deref_exp =
 let check_dereference_error tenv pdesc (prop : Prop.normal Prop.t) lexp loc =
   let pname = Procdesc.get_proc_name pdesc in
   let root = Exp.root_of_lexp lexp in
-  let nullable_var_opt = is_only_pt_by_fld_or_param_nullable pdesc tenv prop root in
+  let nullable_var_opt =
-  let is_deref_of_nullable =
     let is_definitely_non_null exp prop = Prover.check_disequal tenv prop exp Exp.zero in
-    Config.report_nullable_inconsistency && Option.is_some nullable_var_opt
+    if Config.report_nullable_inconsistency then
-    && not (is_definitely_non_null root prop)
+      match is_only_pt_by_fld_or_param_nullable pdesc tenv prop root with
+      | Some _ as nullable_var when not (is_definitely_non_null root prop) ->
+          nullable_var
+      | _ ->
+          None
+    else None
   in
   let relevant_attributes_getters = [Attribute.get_resource tenv; Attribute.get_undef tenv] in
   let get_relevant_attributes exp =
@@ -1597,21 +1601,18 @@ let check_dereference_error tenv pdesc (prop : Prop.normal Prop.t) lexp loc =
         in
         get_relevant_attributes root_no_offset
   in
-  ( if Prover.check_zero tenv (Exp.root_of_lexp root) || is_deref_of_nullable then
+  ( if Prover.check_zero tenv (Exp.root_of_lexp root) || Option.is_some nullable_var_opt then
     let deref_str =
-      if is_deref_of_nullable then
       match nullable_var_opt with
       | Some str ->
-            if is_weak_captured_var pdesc str then
+          if is_weak_captured_var pdesc str then Localise.deref_str_weak_variable_in_block None str
-              Localise.deref_str_weak_variable_in_block None str
           else Localise.deref_str_nullable None str
       | None ->
-            Localise.deref_str_nullable None ""
+          Localise.deref_str_null None
-      else Localise.deref_str_null None
     in
     let err_desc =
-      Errdesc.explain_dereference pname tenv ~use_buckets:true ~is_nullable:is_deref_of_nullable
+      Errdesc.explain_dereference pname tenv ~use_buckets:true
-        deref_str prop loc
+        ~is_nullable:(Option.is_some nullable_var_opt) deref_str prop loc
     in
     if Localise.is_parameter_not_null_checked_desc err_desc then
       raise (Exceptions.Parameter_not_null_checked (err_desc, __POS__))