Remove dead Sig_class and Sig_class_type signature variants (#8470)

Types.signature_item carried Sig_class and Sig_class_type (OCaml class /
class-type items, each `of unit` dummy AST nodes). ReScript has no
classes, so the parser and type checker never construct them; every
match arm was assert false / identity / skip.

Remove both variants and all their handling across the type system
(btype, subst, env, mtype, includemod, printtyp, translmod,
transl_recmodule), gentype, and analysis. Also drop the stale
commented-out get_string block in lam_print.ml referencing the old
3-arg Sig_class form, and simplify the now-trivial filter_rem_sig.

The frozen parsetree0 Pstr_class/Psig_class dummies are independent and
left untouched.

Author: JonoPrest

CHANGELOG.md

@@ -74,6 +74,7 @@
 - Remove the unreachable `Longident.Lapply` constructor (OCaml's applicative-functor path syntax `F(X).t`, which ReScript's grammar cannot produce). https://github.com/rescript-lang/rescript/pull/8469
 - Refactor analysis for server side use. https://github.com/rescript-lang/rescript/pull/8478
 - Remove unused files. https://github.com/rescript-lang/rescript/pull/8481
+- Remove the dead `Sig_class`/`Sig_class_type` signature variants (OCaml class items, which ReScript cannot produce). https://github.com/rescript-lang/rescript/pull/8470
 
 # 13.0.0-alpha.4
 

analysis/src/create_interface.ml

@@ -263,12 +263,6 @@ let print_signature ~extractor ~signature =
       in
       Buffer.add_string buf (indent ^ new_item_str ^ "\n");
       process_signature ~indent items
-    | Sig_class _ :: items ->
-      (* not needed *)
-      process_signature ~indent items
-    | Sig_class_type _ :: items ->
-      (* not needed *)
-      process_signature ~indent items
     | [] -> ()
   and process_module_type ~indent (mt : Types.module_type) =
     match mt with

compiler/core/lam_print.ml

@@ -256,33 +256,6 @@ let flatten (lam : Lam.t) : (print_kind * Ident.t * Lam.t) list * Lam.t =
     aux (Ext_list.map bind_args (fun (id, l) -> (Recursive, id, l))) body
   | _ -> assert false
 
-(* let get_string ((id : Ident.t), (pos : int)) (env : Env.t) : string =
-   match  Env.find_module (Pident id) env with
-   | {md_type = Mty_signature signature  ; _ } ->
-    (* Env.prefix_idents, could be cached  *)
-    let serializable_sigs =
-      Ext_list.filter (fun x ->
-          match x with
-          | Sig_typext _
-          | Sig_module _
-          | Sig_class _ -> true
-          | Sig_value(_, {val_kind = Val_prim _}) -> false
-                           | Sig_value _ -> true
-                           | _ -> false
-                           ) signature  in
-                           (begin match Ext_list.nth_opt  serializable_sigs  pos  with
-                           | Some (Sig_value (i,_)
-                           | Sig_module (i,_,_)
-                           | Sig_typext (i,_,_)
-                           | Sig_modtype(i,_)
-                           | Sig_class (i,_,_)
-                           | Sig_class_type(i,_,_)
-                           | Sig_type(i,_,_)) -> i
-                           | None -> assert false
-                           end).name
-                           | _ -> assert false
-*)
-
 let lambda ppf v =
   let rec lam ppf (l : Lam.t) =
     match l with

compiler/gentype/translate_signature_from_types.ml

@@ -93,12 +93,6 @@ and translate_signature_item_from_types ~config ~output_file_relative ~resolver
   | Types.Sig_modtype _ ->
     log_not_implemented ("Sig_modtype " ^ __LOC__);
     Translation.empty
-  | Types.Sig_class _ ->
-    log_not_implemented ("Sig_class " ^ __LOC__);
-    Translation.empty
-  | Types.Sig_class_type _ ->
-    log_not_implemented ("Sig_class_type " ^ __LOC__);
-    Translation.empty
 
 (** Like translateSignature but from Types not Typedtree *)
 and translate_signature_from_types ~config ~output_file_relative ~resolver

compiler/gentype/translate_type_expr_from_types.ml

@@ -750,8 +750,7 @@ and signature_to_module_runtime_representation ~config ~type_vars_gen ~type_env
                }
              in
              (dependencies, [field])
-           | Types.Sig_type _ | Types.Sig_typext _ | Types.Sig_modtype _
-           | Types.Sig_class _ | Types.Sig_class_type _ ->
+           | Types.Sig_type _ | Types.Sig_typext _ | Types.Sig_modtype _ ->
              ([], []))
   in
   let dependencies, fields =

compiler/ml/btype.ml

@@ -335,8 +335,6 @@ let type_iterators =
     | Sig_typext (_, td, _) -> it.it_extension_constructor it td
     | Sig_module (_, md, _) -> it.it_module_declaration it md
     | Sig_modtype (_, mtd) -> it.it_modtype_declaration it mtd
-    | Sig_class () -> assert false
-    | Sig_class_type () -> assert false
   and it_value_description it vd = it.it_type_expr it vd.val_type
   and it_type_declaration it td =
     List.iter (it.it_type_expr it) td.type_params;

compiler/ml/env.ml

@@ -1454,8 +1454,6 @@ let rec prefix_idents root pos sub = function
       prefix_idents root pos (Subst.add_modtype id (Mty_ident p) sub) rem
     in
     (p :: pl, final_sub)
-  | Sig_class _ :: _ -> assert false
-  | Sig_class_type _ :: _ -> assert false
 
 let prefix_idents root sub sg =
   if sub = Subst.identity then (
@@ -1551,9 +1549,7 @@ and components_of_module_maker (env, sub, path, mty) =
           let decl' = Subst.modtype_declaration sub decl in
           c.comp_modtypes <-
             Tbl.add (Ident.name id) (decl', nopos) c.comp_modtypes;
-          env := store_modtype id decl !env
-        | Sig_class () -> assert false
-        | Sig_class_type () -> assert false)
+          env := store_modtype id decl !env)
       sg pl;
     Some (Structure_comps c)
   | Mty_functor (param, _ty_arg, ty_res) ->
@@ -1796,8 +1792,6 @@ let add_item comp env =
   | Sig_typext (id, ext, _) -> add_extension ~check:false id ext env
   | Sig_module (id, md, _) -> add_module_declaration ~check:false id md env
   | Sig_modtype (id, decl) -> add_modtype id decl env
-  | Sig_class () -> env
-  | Sig_class_type () -> env
 
 let rec add_signature sg env =
   match sg with

compiler/ml/includemod.ml

@@ -126,20 +126,13 @@ let item_ident_name = function
   | Sig_typext (id, d, _) -> (id, d.ext_loc, Field_typext (Ident.name id))
   | Sig_module (id, d, _) -> (id, d.md_loc, Field_module (Ident.name id))
   | Sig_modtype (id, d) -> (id, d.mtd_loc, Field_modtype (Ident.name id))
-  | Sig_class () -> assert false
-  | Sig_class_type () -> assert false
 
 let is_runtime_component = function
   | Sig_value (_, {val_kind = Val_prim _})
   | Sig_type (_, _, _)
-  | Sig_modtype (_, _)
-  | Sig_class_type () ->
+  | Sig_modtype (_, _) ->
     false
-  | Sig_value (_, _)
-  | Sig_typext (_, _, _)
-  | Sig_module (_, _, _)
-  | Sig_class () ->
-    true
+  | Sig_value (_, _) | Sig_typext (_, _, _) | Sig_module (_, _, _) -> true
 
 (* Print a coercion *)
 
@@ -301,7 +294,6 @@ and signatures ~loc env cxt subst sig1 sig2 =
       | Sig_modtype (i, _)
       | Sig_type (i, _, _) ->
         Ident.name i
-      | Sig_class () | Sig_class_type () -> assert false
     in
     List.fold_right
       (fun item fields ->
@@ -360,8 +352,7 @@ and signatures ~loc env cxt subst sig1 sig2 =
           | Sig_module _ -> Subst.add_module id2 (Pident id1) subst
           | Sig_modtype _ ->
             Subst.add_modtype id2 (Mty_ident (Pident id1)) subst
-          | Sig_value _ | Sig_typext _ | Sig_class _ | Sig_class_type () ->
-            subst
+          | Sig_value _ | Sig_typext _ -> subst
         in
         pair_components new_subst ((item1, item2, pos1) :: paired) unpaired rem
       | exception Not_found ->
@@ -399,8 +390,6 @@ and signature_components ~loc old_env env cxt subst paired =
   | (Sig_modtype (id1, info1), Sig_modtype (_id2, info2), _pos) :: rem ->
     modtype_infos ~loc env cxt subst id1 info1 info2;
     comps_rec rem
-  | (Sig_class (), Sig_class (), _) :: _ -> assert false
-  | (Sig_class_type (), Sig_class_type (), _pos) :: _ -> assert false
   | _ -> assert false
 
 and module_declarations ~loc env cxt subst id1 md1 md2 =

compiler/ml/mtype.ml

@@ -89,11 +89,7 @@ and strengthen_sig ~aliasable env sg p pos =
     in
     Sig_modtype (id, newdecl)
     :: strengthen_sig ~aliasable (Env.add_modtype id decl env) rem p pos
-    (* Need to add the module type in case it is manifest *)
-  | (Sig_class _ as sigelt) :: rem ->
-    sigelt :: strengthen_sig ~aliasable env rem p (pos + 1)
-  | (Sig_class_type _ as sigelt) :: rem ->
-    sigelt :: strengthen_sig ~aliasable env rem p pos
+(* Need to add the module type in case it is manifest *)
 
 and strengthen_decl ~aliasable env md p =
   match md.md_type with
@@ -160,9 +156,7 @@ let nondep_supertype env mid mty =
                 {mtd_type = None; mtd_loc = Location.none; mtd_attributes = []}
               )
             :: rem'
-          | _ -> raise Not_found))
-      | Sig_class () -> assert false
-      | Sig_class_type () -> assert false)
+          | _ -> raise Not_found)))
   and nondep_modtype_decl env mtd =
     {mtd with mtd_type = Misc.may_map (nondep_mty env Strict) mtd.mtd_type}
   in
@@ -229,8 +223,7 @@ and type_paths_sig env p pos sg =
         p (pos + 1) rem
   | Sig_modtype (id, decl) :: rem ->
     type_paths_sig (Env.add_modtype id decl env) p pos rem
-  | (Sig_typext _ | Sig_class _) :: rem -> type_paths_sig env p (pos + 1) rem
-  | Sig_class_type _ :: rem -> type_paths_sig env p pos rem
+  | Sig_typext _ :: rem -> type_paths_sig env p (pos + 1) rem
 
 let rec no_code_needed env mty =
   match scrape env mty with
@@ -252,9 +245,8 @@ and no_code_needed_sig env sg =
     && no_code_needed_sig
          (Env.add_module_declaration ~check:false id md env)
          rem
-  | (Sig_type _ | Sig_modtype _ | Sig_class_type _) :: rem ->
-    no_code_needed_sig env rem
-  | (Sig_typext _ | Sig_class _) :: _ -> false
+  | (Sig_type _ | Sig_modtype _) :: rem -> no_code_needed_sig env rem
+  | Sig_typext _ :: _ -> false
 
 (* Check whether a module type may return types *)
 
@@ -286,8 +278,7 @@ and contains_type_item env = function
        is kept local to expressions. *)
     raise Exit
   | Sig_module (_, {md_type = mty}, _) -> contains_type env mty
-  | Sig_value _ | Sig_type _ | Sig_typext _ | Sig_class _ | Sig_class_type _ ->
-    ()
+  | Sig_value _ | Sig_type _ | Sig_typext _ -> ()
 
 let contains_type env mty =
   try

compiler/ml/printtyp.ml

@@ -1071,10 +1071,7 @@ let wrap_env fenv ftree arg =
   set_printing_env env;
   tree
 
-let filter_rem_sig item rem =
-  match (item, rem) with
-  | Sig_class_type _, tydecl1 :: tydecl2 :: rem -> ([tydecl1; tydecl2], rem)
-  | _ -> ([], rem)
+let filter_rem_sig _item rem = ([], rem)
 
 let dummy =
   {
@@ -1161,8 +1158,6 @@ and trees_of_sigitem = function
     in
     [tree_of_module id md.md_type rs ~ellipsis]
   | Sig_modtype (id, decl) -> [tree_of_modtype_declaration id decl]
-  | Sig_class () -> []
-  | Sig_class_type () -> []
 
 and tree_of_modtype_declaration id decl =
   let mty =