[nullsafe] Fix a bug in handling of modelled nullable fields

Summary:
The problem is that `Models.is_field_nonnullable` didn't differentiate
between
- having a nullable model (in which case we want the field to be NULLABLE),
- not having a model at all (in which case we want the field to be THIRDPARTY_NONNULL).

The problem was noticed only now because previously we didn't have any
NULLABLE field models.

Reviewed By: ngorogiannis

Differential Revision: D27709508

fbshipit-source-id: b98c8f86f

Author: artempyanykh

infer/src/nullsafe/AnnotatedField.ml

@@ -89,9 +89,14 @@ let get tenv field_name ~class_typ ~class_under_analysis =
         (* This field is artifact of codegen and is not visible to the user.
            Surfacing it as non-strict is non-actionable for the user *)
         AnnotatedNullability.StrictNonnull SyntheticField
-      else if Models.is_field_nonnullable field_name then
-        AnnotatedNullability.StrictNonnull ModelledNonnull
-      else nullability
+      else
+        match Models.is_field_nonnullable field_name with
+        | Some true ->
+            AnnotatedNullability.StrictNonnull ModelledNonnull
+        | Some false ->
+            AnnotatedNullability.Nullable ModelledNullable
+        | _ ->
+            nullability
     else nullability
   in
   let field_class =

infer/src/nullsafe/modelTables.ml

@@ -747,6 +747,7 @@ let field_nullability =
   ; ( "android.content.pm.ResolveInfo.providerInfo"
     , n (* Exactly one of activityInfo, serviceInfo, or providerInfo will be non-null. *) )
   ; ("android.content.res.Configuration.locale", o)
+  ; ("android.graphics.BitmapFactory$Options.inBitmap", n)
   ; ("android.graphics.Paint.Align.CENTER", o)
   ; ("android.graphics.Paint.Align.LEFT", o)
   ; ("android.graphics.Paint.Align.RIGHT", o)

infer/src/nullsafe/models.ml

@@ -134,5 +134,12 @@ let find_nonnullable_alternative proc_name =
 
 
 let is_field_nonnullable field_name =
-  Hashtbl.find_opt field_nullability_table (Fieldname.to_full_string field_name)
-  |> Option.value_map ~f:(fun is_nullable -> not is_nullable) ~default:false
+  Logging.d_with_indent ~name:"is_field_nonnullable" (fun () ->
+      let full_name = Fieldname.to_full_string field_name in
+      let from_model =
+        Hashtbl.find_opt field_nullability_table full_name
+        (* Models return `is_nullable`, we need `is_notnull` *)
+        |> Option.map ~f:not
+      in
+      Logging.d_printfln "Model for %s: %a" full_name (Pp.option Format.pp_print_bool) from_model ;
+      from_model )

infer/src/nullsafe/models.mli

@@ -48,5 +48,5 @@ val find_nonnullable_alternative : Procname.Java.t -> ModelTables.nonnull_altern
 (** Check if a (nullable) method has a non-nullable alternative: A method that does the same as
     [proc_name] but asserts the result is not null before returning to the caller. *)
 
-val is_field_nonnullable : Fieldname.t -> bool
-(** Check if a given field is known to be a non-nullable *)
+val is_field_nonnullable : Fieldname.t -> bool option
+(** Check if a given field has known nullability: true = nonnull, false = null *)

infer/src/nullsafe/typeCheck.ml

@@ -260,20 +260,26 @@ let funcall_exp_to_original_pvar_exp tenv curr_pname typestate exp ~is_assignmen
 
 let add_field_to_typestate_if_absent tenv access_loc typestate pvar object_origin field_name
     ~field_class_typ ~class_under_analysis =
-  match TypeState.lookup_pvar pvar typestate with
-  | Some _ ->
-      typestate
-  | None -> (
-    match AnnotatedField.get tenv field_name ~class_typ:field_class_typ ~class_under_analysis with
-    | Some AnnotatedField.{annotated_type= field_type} ->
-        let range =
-          ( field_type.typ
-          , InferredNullability.create
-              (TypeOrigin.Field {object_origin; field_name; field_type; access_loc}) )
-        in
-        TypeState.add ~descr:"add_field_to_typestate_if_absent" pvar range typestate
-    | None ->
-        typestate )
+  L.d_with_indent ~name:"add_field_to_typestate_if_absent" (fun () ->
+      match TypeState.lookup_pvar pvar typestate with
+      | Some _ ->
+          typestate
+      | None -> (
+        match
+          AnnotatedField.get tenv field_name ~class_typ:field_class_typ ~class_under_analysis
+        with
+        | Some AnnotatedField.{annotated_type= field_type} ->
+            let range =
+              ( field_type.typ
+              , InferredNullability.create
+                  (TypeOrigin.Field {object_origin; field_name; field_type; access_loc}) )
+            in
+            let _, inferred_nullability = range in
+            L.d_printfln "Fieldname %a: typ=%a, inferred_nullability=%a" Fieldname.pp field_name
+              AnnotatedType.pp field_type InferredNullability.pp inferred_nullability ;
+            TypeState.add ~descr:"add_field_to_typestate_if_absent" pvar range typestate
+        | None ->
+            typestate ) )
 
 
 (* This does two things: