[backend] Do not add return annotations to parameters of functions that are skipped

Reviewed By: sblackshear

Differential Revision: D5737278

fbshipit-source-id: 50ee2c8

infer/src/backend/Attribute.ml

@@ -194,17 +194,30 @@ let rec nullify_exp_with_objc_null tenv prop exp =
   | _
    -> prop
 
-(** mark Exp.Var's or Exp.Lvar's as undefined *)
-let mark_vars_as_undefined tenv prop vars_to_mark callee_pname ret_annots loc path_pos =
-  let att_undef = PredSymb.Aundef (callee_pname, ret_annots, loc, path_pos) in
-  let mark_var_as_undefined exp prop =
+(** mark Exp.Var's or Exp.Lvar's as undefined
+The annotations of the return type of the method get propagated to the return id,
+with the exception of when the return type is a struct, and we translate it as passing a reference
+to the method.  *)
+let mark_vars_as_undefined tenv prop ~ret_exp_opt ~undefined_actuals_by_ref callee_pname ret_annots
+    loc path_pos =
+  let mark_var_as_undefined ~annot exp prop =
     match exp with
     | Exp.Var _ | Lvar _
-     -> add_or_replace tenv prop (Apred (att_undef, [exp]))
+     -> let att_undef = PredSymb.Aundef (callee_pname, annot, loc, path_pos) in
+        add_or_replace tenv prop (Apred (att_undef, [exp]))
     | _
      -> prop
   in
-  List.fold ~f:(fun prop id -> mark_var_as_undefined id prop) ~init:prop vars_to_mark
+  let prop_with_ret_attr =
+    match ret_exp_opt with
+    | Some ret_exp
+     -> mark_var_as_undefined ~annot:ret_annots ret_exp prop
+    | None
+     -> prop
+  in
+  List.fold
+    ~f:(fun prop id -> mark_var_as_undefined ~annot:[] id prop)
+    ~init:prop_with_ret_attr undefined_actuals_by_ref
 
 (** type for arithmetic problems *)
 type arith_problem =

infer/src/backend/Attribute.mli

@@ -92,8 +92,8 @@ val nullify_exp_with_objc_null : Tenv.t -> Prop.normal Prop.t -> Exp.t -> Prop.n
     remove the attribute and conjoin an equality to zero. *)
 
 val mark_vars_as_undefined :
-  Tenv.t -> Prop.normal Prop.t -> Exp.t list -> Typ.Procname.t -> Annot.Item.t -> Location.t
-  -> PredSymb.path_pos -> Prop.normal Prop.t
+  Tenv.t -> Prop.normal Prop.t -> ret_exp_opt:Exp.t option -> undefined_actuals_by_ref:Exp.t list
+  -> Typ.Procname.t -> Annot.Item.t -> Location.t -> PredSymb.path_pos -> Prop.normal Prop.t
 (** mark Exp.Var's or Exp.Lvar's as undefined *)
 
 (** type for arithmetic problems *)

infer/src/backend/symExec.ml

@@ -1578,16 +1578,12 @@ and unknown_or_scan_call ~is_scan ret_type_option ret_annots
     [(Tabulation.remove_constant_string_class tenv pre_final, path)]
   else
     (* otherwise, add undefined attribute to retvals and actuals passed by ref *)
-    let exps_to_mark =
-      let ret_exps = Option.value_map ~f:(fun (id, _) -> [Exp.Var id]) ~default:[] ret_id in
-      List.fold
-        ~f:(fun exps_to_mark (exp, _, _) -> exp :: exps_to_mark)
-        ~init:ret_exps actuals_by_ref
-    in
+    let undefined_actuals_by_ref = List.map ~f:(fun (exp, _, _) -> exp) actuals_by_ref in
+    let ret_exp_opt = Option.map ~f:(fun (id, _) -> Exp.Var id) ret_id in
     let prop_with_undef_attr =
       let path_pos = State.get_path_pos () in
-      Attribute.mark_vars_as_undefined tenv pre_final exps_to_mark callee_pname ret_annots loc
-        path_pos
+      Attribute.mark_vars_as_undefined tenv pre_final ~ret_exp_opt ~undefined_actuals_by_ref
+        callee_pname ret_annots loc path_pos
     in
     let reason = "function or method not found" in
     let skip_path = Paths.Path.add_skipped_call path callee_pname reason in

infer/tests/codetoanalyze/objc/errors/Makefile

@@ -97,6 +97,7 @@ SOURCES_ARC = \
   npe/nil_in_dictionary_literal.m \
   npe/npe_conditional.m \
   npe/npe_self.m \
+	npe/Npe_self_annotation.m \
   npe/nullable.m \
   property/ExplicitIvarName.m \
   shared/block/dispatch_examples.m \

infer/tests/codetoanalyze/objc/errors/npe/Npe_self_annotation.m

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2017 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+#import <Foundation/Foundation.h>
+
+@interface B : NSObject
+
+@end
+
+@interface A
+
++ (nullable NSData*)foo:(B*)b;
+
+@end
+
+@implementation B {
+  B* _decodedMetadata;
+}
+
+- (B*)decodedMetadata {
+  NSData* metadata = [A foo:self];
+  return _decodedMetadata; // No NPE here
+}
+@end