[nullsafe][annotation graph] Don't try to annotate primitives

Summary:
In the previous diff we introduced
AnnotatedNullability.is_annotatable_as_nullable method.

Lets now use it in all places where we issue ProvisionallyNullable
annotation.

This will lead to more precise nullability graph (without attempts to
annotate primitives).

Reviewed By: artempyanykh

Differential Revision: D24650951

fbshipit-source-id: 8ea0bb97d

infer/src/nullsafe/AnnotatedSignature.ml

@@ -47,18 +47,25 @@ let nullability_for_return ~proc_name ~is_callee_in_trust_list ~nullsafe_mode ~i
     AnnotatedNullability.of_type_and_annotation ~is_callee_in_trust_list ~nullsafe_mode
       ~is_third_party ret_type ret_annotations
   in
-  (* if any param is annotated with propagates nullable, then the result is nullable *)
+  (* if any param is annotated with propagates nullable, the return nullability is also nullable *)
+  let nullability =
     match nullability with
     | AnnotatedNullability.Nullable _ ->
         nullability (* We already know it is nullable - lets not overwrite the origin *)
     | _ when has_propagates_nullable_in_param ->
         (* if any params is propagates nullable, the return type can be only nullable *)
         AnnotatedNullability.Nullable AnnotatedNullability.HasPropagatesNullableInParam
-  | _ when is_provisional_annotation_mode ->
-      (* Not explicitly annotated with [@Nullable] - make it provisionally nullable  *)
-      AnnotatedNullability.ProvisionallyNullable (ProvisionalAnnotation.Method proc_name)
     | _ ->
         nullability
+  in
+  let final_nullability =
+    if
+      is_provisional_annotation_mode
+      && AnnotatedNullability.can_be_considered_for_provisional_annotation nullability
+    then AnnotatedNullability.ProvisionallyNullable (ProvisionalAnnotation.Method proc_name)
+    else nullability
+  in
+  final_nullability
 
 
 let nullability_for_param ~proc_name ~param_num ~is_callee_in_trust_list ~nullsafe_mode
@@ -67,14 +74,13 @@ let nullability_for_param ~proc_name ~param_num ~is_callee_in_trust_list ~nullsa
     AnnotatedNullability.of_type_and_annotation ~is_callee_in_trust_list ~nullsafe_mode
       ~is_third_party param_type param_annotations
   in
-  match nullability with
-  | AnnotatedNullability.Nullable _ ->
-      nullability
-  | _ when is_provisional_annotation_mode ->
+  if
+    is_provisional_annotation_mode
+    && AnnotatedNullability.can_be_considered_for_provisional_annotation nullability
+  then
     AnnotatedNullability.ProvisionallyNullable
       (ProvisionalAnnotation.Param {method_info= proc_name; num= param_num})
-  | _ ->
-      nullability
+  else nullability
 
 
 (* Given annotations for method signature, extract nullability information