Do not store type parameters as target

Summary:
In this diff, we simplify the representation for storing type parameters in preparation for supporting type variables for classes in PEP695.

Two things I need to follow up on:

1- Do we have to synthesize a target in parents_and_generic_of_target?

2- we should represent type parameters as Type.Variable.t list option

Reviewed By: stroxler

Differential Revision: D61570813

fbshipit-source-id: 1b3f267673f84a892f3ed942b131237374471fe7

source/analysis/classHierarchy.ml

@@ -128,7 +128,7 @@ module Edges = struct
     (* The instantiation of `typing.Generic` that the class inherits from but is not necessarily
        listed explicitly as a parent. It needs to be stored separately because this class may not
        take part in MRO computation. *)
-    generic_base: Target.t option;
+    parameters_as_generic_base_arguments: Type.Argument.t list option;
   }
   [@@deriving sexp, compare]
 end
@@ -145,10 +145,10 @@ let parents_of (module Handler : Handler) target =
 
 let parents_and_generic_of_target (module Handler : Handler) target =
   Handler.edges target
-  >>= fun { parents; generic_base; _ } ->
-  match generic_base with
+  >>= fun { parents; parameters_as_generic_base_arguments; _ } ->
+  match parameters_as_generic_base_arguments with
   | None -> Some parents
-  | Some base -> Some (List.append parents [base])
+  | Some base -> Some (List.append parents [{ target = generic_primitive; arguments = base }])
 
 
 let is_instantiated (module Handler : Handler) annotation =

source/analysis/classHierarchy.mli

@@ -66,7 +66,7 @@ end
 module Edges : sig
   type t = {
     parents: Target.t list;
-    generic_base: Target.t option;
+    parameters_as_generic_base_arguments: Type.Argument.t list option;
   }
   [@@deriving sexp, compare]
 end

source/analysis/classHierarchyEnvironment.ml

@@ -189,7 +189,7 @@ module IncomingDataComputation = struct
           |> deduplicate
           |> remove_extra_edges_to_object
         in
-        let generic_base =
+        let parameters_as_generic_base_arguments =
           let open Option in
           let parsed_bases =
             List.map
@@ -200,10 +200,9 @@ module IncomingDataComputation = struct
           in
           compute_generic_base parsed_bases
           >>= fun base ->
-          extract_supertype (Type.expression base)
-          >>= fun (name, arguments) -> Some { ClassHierarchy.Target.target = name; arguments }
+          extract_supertype (Type.expression base) >>= fun (_, arguments) -> Some arguments
         in
-        Some { ClassHierarchy.Edges.parents; generic_base }
+        Some { ClassHierarchy.Edges.parents; parameters_as_generic_base_arguments }
 end
 
 module OutgoingDataComputation = struct

source/analysis/test/classHierarchyEnvironmentTest.ml

@@ -26,7 +26,7 @@ let test_simple_registration context =
             List.map
               ~f:(fun name -> { ClassHierarchy.Target.target = name; arguments = [] })
               expected_edges;
-          generic_base = None;
+          parameters_as_generic_base_arguments = None;
         }
     in
     assert_equal
@@ -64,11 +64,16 @@ let test_parents_and_inferred_generic_base context =
         arguments = List.map concretes ~f:(fun single -> Type.Argument.Single single);
       }
     in
+    let create_argument_list (_, concretes) =
+      List.map concretes ~f:(fun single -> Type.Argument.Single single)
+    in
+
     let expected =
       Some
         {
           ClassHierarchy.Edges.parents = List.map expected_parents ~f:create_target;
-          generic_base = Option.map expected_inferred_generic_base ~f:create_target;
+          parameters_as_generic_base_arguments =
+            Option.map expected_inferred_generic_base ~f:create_argument_list;
         }
     in
     assert_equal
@@ -325,7 +330,7 @@ let test_updates context =
                   ClassHierarchy.Edges.parents =
                     List.map expectation ~f:(fun name ->
                         { ClassHierarchy.Target.target = name; arguments = [] });
-                  generic_base = None;
+                  parameters_as_generic_base_arguments = None;
                 })
           in
           ClassHierarchyEnvironment.ReadOnly.get_edges read_only ~dependency class_name

source/analysis/test/environmentTest.ml

@@ -1143,7 +1143,7 @@ let test_remove_extra_edges_to_object context =
     (find_unsafe Handler.edges "test.Zero")
     {
       ClassHierarchy.Edges.parents = [{ ClassHierarchy.Target.target = "test.One"; arguments = [] }];
-      generic_base = None;
+      parameters_as_generic_base_arguments = None;
     };
   ()
 

source/test/test.ml

@@ -3671,7 +3671,11 @@ module MockClassHierarchyHandler = struct
     let new_target = { ClassHierarchy.Target.target = successor; arguments } in
     let predecessor_edges =
       match Hashtbl.find edges predecessor with
-      | None -> { ClassHierarchy.Edges.parents = [new_target]; generic_base = None }
+      | None ->
+          {
+            ClassHierarchy.Edges.parents = [new_target];
+            parameters_as_generic_base_arguments = None;
+          }
       | Some ({ ClassHierarchy.Edges.parents; _ } as edges) ->
           { edges with parents = new_target :: parents }
     in
@@ -3683,5 +3687,5 @@ module MockClassHierarchyHandler = struct
     Hashtbl.set
       order.edges
       ~key:annotation
-      ~data:{ ClassHierarchy.Edges.parents = []; generic_base = None }
+      ~data:{ ClassHierarchy.Edges.parents = []; parameters_as_generic_base_arguments = None }
 end