[nullsafe] Remove old traces of modelling the annotation for the field

Summary:
We historically had Model.Inference, which was an attempt to enhance
models with additional abilities to get the annotation.

This feature got removed in D9805110, including removing of the key
condition Models.Inference.field_is_marked.

This code also is not executed: `Config.eradicate` condition
was an old artefact of migrating Eradicate to callback infrastructure:
D1508451. We run eradicate only as a callback as of now, so this flag is
always true.

In follow up diffs we refactor AnnotationSignature module, and this
cleanup simplifies the refactoring.

Reviewed By: ngorogiannis

Differential Revision: D17419173

fbshipit-source-id: 1b30555de

infer/src/nullsafe/AnnotatedSignature.mli

@@ -23,8 +23,5 @@ val mark_nullability : Typ.Procname.t -> t -> bool * bool list -> t
 val get : ProcAttributes.t -> t
 (** Get a method signature with annotations from a proc_attributes. *)
 
-val mk_ia_nullable : Annot.Item.t -> Annot.Item.t
-(** Add the nullable annotation to the item_annotation, if not already present. *)
-
 val pp : Typ.Procname.t -> Format.formatter -> t -> unit
 (** Pretty print a method signature with annotations. *)

infer/src/nullsafe/eradicateChecks.ml

@@ -11,17 +11,7 @@ open! IStd
 
 let get_field_annotation tenv fn typ =
   let lookup = Tenv.lookup tenv in
-  match Typ.Struct.get_field_type_and_annotation ~lookup fn typ with
-  | None ->
-      None
-  | Some (t, ia) ->
-      let ia' =
-        (* TODO (t4968422) eliminate not !Config.eradicate check by marking fields as nullified *)
-        (* outside of Eradicate in some other way *)
-        if not Config.eradicate then AnnotatedSignature.mk_ia_nullable ia else ia
-      in
-      Some (t, ia')
-
+  Typ.Struct.get_field_type_and_annotation ~lookup fn typ
 
 let report_error tenv = TypeErr.report_error tenv (EradicateCheckers.report_error tenv)