[nullsafe] Specify "InferredNonnull" type origin even if it was already Nonnull

Summary:
This will make our analysis more precise. E.g. in the future  we can classify
"condition redundand" warnings by origin, and warn only for
InferredNonnull, or autogenerate fixes based on the origin.

Error messaging does not currently take into account origin for nonnull
types, but this can be changed in the future

Reviewed By: ngorogiannis

Differential Revision: D18685304

fbshipit-source-id: 6a1f263f5

infer/src/nullsafe/InferredNullability.ml

@@ -17,8 +17,6 @@ let is_nonnull_or_declared_nonnull {nullability} =
   match nullability with Nonnull | DeclaredNonnull -> true | _ -> false
 
 
-let is_nonnull {nullability} = match nullability with Nonnull -> true | _ -> false
-
 let to_string {nullability} = Printf.sprintf "[%s]" (Nullability.to_string nullability)
 
 let join t1 t2 =

infer/src/nullsafe/InferredNullability.mli

@@ -25,8 +25,6 @@ val create : TypeOrigin.t -> t
 
 val is_nonnull_or_declared_nonnull : t -> bool
 
-val is_nonnull : t -> bool
-
 val get_origin : t -> TypeOrigin.t
 (** The simple explanation of how was nullability inferred.  *)
 

infer/src/nullsafe/typeCheck.ml

@@ -711,14 +711,12 @@ let rec check_condition_for_sil_prune tenv idenv calls_this find_canonical_dupli
     let handle_pvar typestate' pvar =
       match TypeState.lookup_pvar pvar typestate' with
       | Some (t, current_nullability) ->
-          if not (InferredNullability.is_nonnull current_nullability) then
-            let new_origin =
-              TypeOrigin.InferredNonnull
-                {previous_origin= InferredNullability.get_origin current_nullability}
-            in
-            let new_nullability = InferredNullability.create new_origin in
-            TypeState.add pvar (t, new_nullability) typestate'
-          else typestate'
+          let new_origin =
+            TypeOrigin.InferredNonnull
+              {previous_origin= InferredNullability.get_origin current_nullability}
+          in
+          let new_nullability = InferredNullability.create new_origin in
+          TypeState.add pvar (t, new_nullability) typestate'
       | None ->
           typestate'
     in
@@ -758,9 +756,7 @@ let rec check_condition_for_sil_prune tenv idenv calls_this find_canonical_dupli
       match from_call with
       | EradicateChecks.From_is_true_on_null ->
           (* if f returns true on null, then false branch implies != null *)
-          if not (InferredNullability.is_nonnull inferred_nullability) then
-            set_nonnull e' typestate2
-          else typestate2
+          set_nonnull e' typestate2
       | _ ->
           typestate2 )
   | Exp.BinOp (Binop.Ne, Exp.Const (Const.Cint i), e)
@@ -800,9 +796,7 @@ let rec check_condition_for_sil_prune tenv idenv calls_this find_canonical_dupli
       | EradicateChecks.From_containsKey
       | EradicateChecks.From_instanceof
       | EradicateChecks.From_is_false_on_null ->
-          if not (InferredNullability.is_nonnull inferred_nullability) then
-            set_nonnull e' typestate2
-          else typestate2 )
+          set_nonnull e' typestate2 )
   | Exp.UnOp (Unop.LNot, Exp.BinOp (Binop.Eq, e1, e2), _) ->
       check_condition_for_sil_prune tenv idenv calls_this find_canonical_duplicate loc curr_pname
         curr_pdesc curr_annotated_signature linereader typestate checks true_branch instr_ref