[nullsafe] Treat not annotated synthetic fields as StrictNonnull

Reviewed By: artempyanykh

Differential Revision: D21040264

fbshipit-source-id: 3557c5f60

infer/src/nullsafe/AnnotatedField.ml

@@ -36,6 +36,8 @@ let is_enum_value tenv ~class_typ (field_info : Struct.field_info) =
         false
 
 
+let is_synthetic field_name = String.contains field_name '$'
+
 let get tenv field_name class_typ =
   let open IOption.Let_syntax in
   let lookup = Tenv.lookup tenv in
@@ -59,13 +61,19 @@ let get tenv field_name class_typ =
       ~is_third_party field_typ annotations
   in
   let corrected_nullability =
-    if Nullability.is_nonnullish (AnnotatedNullability.get_nullability nullability) && is_enum_value
-    then
+    if Nullability.is_nonnullish (AnnotatedNullability.get_nullability nullability) then
+      if
+        is_enum_value
         (* Enum values are the special case - they can not be null. So we can strengten nullability.
            Note that if it is nullable, we do NOT change nullability: in this case this is probably
            not an enum value, but just a static field annotated as nullable.
         *)
-      AnnotatedNullability.StrictNonnull EnumValue
+      then AnnotatedNullability.StrictNonnull EnumValue
+      else if is_synthetic (Fieldname.get_field_name field_name) then
+        (* 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 nullability
     else nullability
   in
   let annotated_type = AnnotatedType.{nullability= corrected_nullability; typ= field_typ} in

infer/src/nullsafe/AnnotatedNullability.ml

@@ -39,6 +39,7 @@ and strict_nonnull_origin =
   | StrictMode
   | PrimitiveType
   | EnumValue
+  | SyntheticField
 [@@deriving compare]
 
 let get_nullability = function
@@ -83,6 +84,8 @@ let pp fmt t =
         "primitive"
     | EnumValue ->
         "enum"
+    | SyntheticField ->
+        "synthetic_field"
   in
   match t with
   | Nullable origin ->

infer/src/nullsafe/AnnotatedNullability.mli

@@ -61,6 +61,9 @@ and strict_nonnull_origin =
   | PrimitiveType  (** Primitive types are non-nullable by language design *)
   | EnumValue
       (** Java enum value are statically initialized with non-nulls according to language semantics *)
+  | SyntheticField
+      (** Fake field that is not part of user codebase, but rather artifact of codegen/annotation
+          processor *)
 [@@deriving compare]
 
 val get_nullability : t -> Nullability.t