[Infer][backend] Refactoring attribute categories so as not to conflate resource and undefined attrs

Summary:
`get_resource_or_undef` attribute is weird and was causing problems for me in another diff.
This diff refactors the attribute categories to make resource and undef separate.

infer/src/backend/abs.ml

@@ -1277,13 +1277,15 @@ let check_junk ?original_prop pname tenv prop =
                 (* find the alloc attribute of one of the roots of hpred, if it exists *)
                 let res = ref None in
                 let do_entry e =
-                  match Prop.get_resource_undef_attribute prop e with
+                  match Prop.get_resource_attribute prop e with
                   | Some (Sil.Aresource ({ Sil.ra_kind = Sil.Racquire }) as a) ->
                       L.d_str "ATTRIBUTE: "; Sil.d_exp (Sil.Const (Sil.Cattribute a)); L.d_ln ();
                       res := Some a
-                  | Some (Sil.Aundef _ as a) ->
-                      res := Some a
-                  | _ -> () in
+                  | _ ->
+                      (match Prop.get_undef_attribute prop e with
+                       | Some (Sil.Aundef _ as a) ->
+                           res := Some a
+                       | _ -> ()) in
                 list_iter do_entry entries;
                 !res in
               L.d_decrease_indent 1;

infer/src/backend/errdesc.ml

@@ -20,7 +20,7 @@ let pvar_to_string pvar =
 (** Check whether the hpred is a |-> representing a resource in the Racquire state *)
 let hpred_is_open_resource prop = function
   | Sil.Hpointsto(e, _, _) ->
-      (match Prop.get_resource_undef_attribute prop e with
+      (match Prop.get_resource_attribute prop e with
        | Some (Sil.Aresource { Sil.ra_kind = Sil.Racquire; Sil.ra_res = res }) -> Some res
        | _ -> None)
   | _ ->

infer/src/backend/prop.ml

@@ -1762,7 +1762,10 @@ let get_attribute prop exp category =
               atts)
   with Not_found -> None
 
-let get_resource_undef_attribute prop exp =
+let get_undef_attribute prop exp =
+  get_attribute prop exp Sil.ACundef
+
+let get_resource_attribute prop exp =
   get_attribute prop exp Sil.ACresource
 
 let get_taint_attribute prop exp =

infer/src/backend/prop.mli

@@ -271,8 +271,11 @@ val atom_get_exp_attribute : atom -> (Sil.exp * Sil.attribute) option
 (** Get the attributes associated to the expression, if any *)
 val get_exp_attributes : 'a t -> exp -> attribute list
 
-(** Get the resource attribute associated to the expression, if any, or undefined *)
-val get_resource_undef_attribute : 'a t -> exp -> attribute option
+(** Get the undef attribute associated to the expression, if any *)
+val get_undef_attribute : 'a t -> exp -> attribute option
+
+(** Get the resource attribute associated to the expression, if any *)
+val get_resource_attribute : 'a t -> exp -> attribute option
 
 (** Get the taint attribute associated to the expression, if any *)
 val get_taint_attribute : 'a t -> exp -> attribute option

infer/src/backend/rearrange.ml

@@ -970,7 +970,8 @@ let check_dereference_error pdesc (prop : Prop.normal Prop.t) lexp loc =
     !Config.report_nullable_inconsistency && !Config.curr_language = Config.Java &&
     not (is_definitely_non_null root prop) && is_only_pt_by_nullable_fld_or_param root in
   let relevant_attributes_getters = [
-    Prop.get_resource_undef_attribute;
+    Prop.get_resource_attribute;
+    Prop.get_undef_attribute;
   ] in
   let get_relevant_attributes exp =
     let rec fold_getters = function

infer/src/backend/sil.ml

@@ -635,6 +635,8 @@ and attribute_category =
   | ACtaint
   | ACdiv0
   | ACobjc_null
+  | ACundef
+  | ACretval
 
 (** Constants *)
 and const =
@@ -1131,14 +1133,14 @@ let attribute_category_equal att1 att2 =
 let attribute_to_category att =
   match att with
   | Aresource _
-  | Adangling _
-  | Aretval _
-  | Aundef _ -> ACresource
+  | Adangling _ -> ACresource
   | Ataint
   | Auntaint -> ACtaint
   | Aautorelease -> ACautorelease
   | Adiv0 _ -> ACdiv0
   | Aobjc_null _ -> ACobjc_null
+  | Aretval _ -> ACretval
+  | Aundef _ -> ACundef
 
 let attr_is_undef = function
   | Aundef _ -> true

infer/src/backend/sil.mli

@@ -270,6 +270,8 @@ and attribute_category =
   | ACtaint
   | ACdiv0
   | ACobjc_null
+  | ACundef
+  | ACretval
 
 (** Constants *)
 and const =

infer/src/backend/symExec.ml

@@ -131,7 +131,7 @@ let rec apply_offlist
             lookup_inst := Some inst_curr;
             let alloc_attribute_opt =
               if inst_curr = Sil.Iinitial then None
-              else Prop.get_resource_undef_attribute p root_lexp in
+              else Prop.get_undef_attribute p root_lexp in
             let deref_str = Localise.deref_str_uninitialized alloc_attribute_opt in
             let err_desc = Errdesc.explain_memory_access deref_str p (State.get_loc ()) in
             let exn = (Exceptions.Uninitialized_value (err_desc, try assert false with Assert_failure x -> x)) in
@@ -815,7 +815,7 @@ let handle_objc_method_call actual_pars actual_params pre tenv cfg ret_ids pdesc
   else
     let res = Tabulation.exe_function_call tenv cfg ret_ids pdesc callee_pname loc actual_params pre path in
     let is_undef =
-      Option.map_default Sil.attr_is_undef false (Prop.get_resource_undef_attribute pre receiver) in
+      Option.is_some (Prop.get_undef_attribute pre receiver) in
     if !Config.footprint && not is_undef then
       let res_null = (* returns: (objc_null(res) /\ receiver=0) or an empty list of results *)
         let pre_with_attr_or_null = add_objc_null_attribute_or_nullify_result pre in
@@ -1561,7 +1561,7 @@ module ModelBuiltins = struct
 
   let is_undefined_opt prop n_lexp =
     let is_undef =
-      Option.map_default Sil.attr_is_undef false (Prop.get_resource_undef_attribute prop n_lexp) in
+      Option.is_some (Prop.get_undef_attribute prop n_lexp) in
     is_undef && (!Config.angelic_execution || !Config.optimistic_cast)
 
   (** Creates an object in the heap with a given type, when the object is not known to be null or when it doesn't
@@ -1723,7 +1723,7 @@ module ModelBuiltins = struct
     (execute___instanceof_cast cfg pdesc instr tenv _prop path ret_ids args callee_pname loc false)
 
   let set_resource_attribute prop path n_lexp loc ra_res =
-    let prop' = match Prop.get_resource_undef_attribute prop n_lexp with
+    let prop' = match Prop.get_resource_attribute prop n_lexp with
       | Some (Sil.Aresource (_ as ra)) ->
           let check_attr_change att_old att_new = () in
           Prop.add_or_replace_exp_attribute check_attr_change prop n_lexp (Sil.Aresource { ra with Sil.ra_res = ra_res })

infer/src/backend/tabulation.ml

@@ -264,12 +264,14 @@ let check_dereferences callee_pname actual_pre sub spec_pre formal_params =
     if Prop.has_dangling_uninit_attribute spec_pre e then
       Some (Deref_undef_exp, desc false (Localise.deref_str_dangling (Some Sil.DAuninit)) )
     else if Sil.exp_equal e_sub Sil.exp_minus_one then Some (Deref_minusone, desc true (Localise.deref_str_dangling None))
-    else match Prop.get_resource_undef_attribute actual_pre e_sub with
-      | Some (Sil.Aundef (s, loc, pos)) ->
-          Some (Deref_undef (s, loc, pos), desc false (Localise.deref_str_undef (s, loc)))
+    else match Prop.get_resource_attribute actual_pre e_sub with
       | Some (Sil.Aresource ({ Sil.ra_kind = Sil.Rrelease } as ra)) ->
           Some (Deref_freed ra, desc true (Localise.deref_str_freed ra))
-      | _ -> None in
+      | _ ->
+          (match Prop.get_undef_attribute actual_pre e_sub with
+           | Some (Sil.Aundef (s, loc, pos)) ->
+               Some (Deref_undef (s, loc, pos), desc false (Localise.deref_str_undef (s, loc)))
+           | _ -> None) in
   let check_hpred = function
     | Sil.Hpointsto (lexp, se, _) ->
         check_dereference (Sil.root_of_lexp lexp) se
@@ -324,7 +326,7 @@ let check_path_errors_in_post caller_pname post post_path =
     Also, update any Aresource attributes to refer to the caller *)
 let post_process_post
     caller_pname callee_pname loc actual_pre ((post: Prop.exposed Prop.t), post_path) =
-  let actual_pre_has_freed_attribute e = match Prop.get_resource_undef_attribute actual_pre e with
+  let actual_pre_has_freed_attribute e = match Prop.get_resource_attribute actual_pre e with
     | Some (Sil.Aresource ({ Sil.ra_kind = Sil.Rrelease })) -> true
     | _ -> false in
   let atom_update_alloc_attribute = function
@@ -1087,7 +1089,7 @@ let exe_call_postprocess tenv ret_ids trace_call callee_pname loc initial_prop r
       let mark_id_as_retval (p, path) =
         (* check if the retval already has an important resource that should not be overwritten *)
         let has_important_resource_attr =
-          match Prop.get_resource_undef_attribute p ret_var with
+          match Prop.get_resource_attribute p ret_var with
           | Some (Sil.Aresource ({ Sil.ra_res = Sil.Rfile; })) -> true
           | _ -> false in
         if has_important_resource_attr then p, path