Fix ord variant wildcard_case to_int type pre-OCaml 4.11 (PR #260)

src_plugins/ord/ppx_deriving_ord.cppo.ml

@@ -35,10 +35,14 @@ let reduce_compare l =
   | [] -> [%expr 0]
   | x :: xs -> List.fold_left compare_reduce x xs
 
-let wildcard_case ~typ int_cases =
+let wildcard_case ?typ int_cases =
   let loc = !Ast_helper.default_loc in
+  let typ = match typ with
+    | Some typ -> typ
+    | None -> [%type: _] (* don't constrain *)
+  in
   Exp.case [%pat? _] [%expr
-    let to_int: [%t typ] -> Ppx_deriving_runtime.int = [%e Exp.function_ int_cases] in
+    let to_int (x: [%t typ]) = [%e Exp.match_ [%expr x] int_cases] in
     Ppx_deriving_runtime.compare (to_int lhs) (to_int rhs)]
 
 let pattn side typs =
@@ -163,7 +167,7 @@ and expr_of_typ quoter typ =
           | _ -> assert false)
       in
       [%expr fun lhs rhs ->
-        [%e Exp.match_ [%expr lhs, rhs] (cases @ [wildcard_case ~typ int_cases])]]
+        [%e Exp.match_ [%expr lhs, rhs] (cases @ [wildcard_case int_cases])]]
     | { ptyp_desc = Ptyp_var name } -> evar ("poly_"^name)
     | { ptyp_desc = Ptyp_alias (typ, _) } -> expr_of_typ typ
     | { ptyp_loc } ->
@@ -185,6 +189,24 @@ let sig_of_type ~options ~path type_decl =
 let str_of_type ~options ~path ({ ptype_loc = loc } as type_decl) =
   parse_options options;
   let quoter = Ppx_deriving.create_quoter () in
+  (* Capture type in helper module outside Ppx_deriving_runtime wrapper (added by sanitize).
+     Required for to_int constraint in variant type wildcard_case if the type name
+     conflicts with a Stdlib type from Ppx_deriving_runtime (e.g. bool in test).
+     In that case we must refer to the type being declared, not the one opened by Ppx_deriving_runtime. *)
+  let helper_type =
+    Type.mk ~loc ~attrs:[Ppx_deriving.attr_warning [%expr "-unused-type-declaration"]]
+      ~params:type_decl.ptype_params
+      ~manifest:(Ppx_deriving.core_type_of_type_decl type_decl)
+      (mkloc "t" loc)
+  in
+  let helper_typ =
+    let name = mkloc (Longident.parse "Ppx_deriving_ord_helper.t") loc in
+    let params = match helper_type.ptype_params with
+      | [] -> []
+      | _ :: _ -> [Typ.any ()] (* match all params with single wildcard *)
+    in
+    Typ.constr name params
+  in
   let comparator =
     match type_decl.ptype_kind, type_decl.ptype_manifest with
     | Ptype_abstract, Some manifest -> expr_of_typ quoter manifest
@@ -208,7 +230,7 @@ let str_of_type ~options ~path ({ ptype_loc = loc } as type_decl) =
           )
       in
       [%expr fun lhs rhs ->
-        [%e Exp.match_ [%expr lhs, rhs] (cases @ [wildcard_case ~typ:[%type: Ppx_deriving_ord_helper.t] int_cases])]]
+        [%e Exp.match_ [%expr lhs, rhs] (cases @ [wildcard_case ~typ:helper_typ int_cases])]]
     | Ptype_record labels, _ ->
       let exprs =
         labels |> List.map (fun ({ pld_name = { txt = name }; _ } as pld) ->
@@ -235,16 +257,6 @@ let str_of_type ~options ~path ({ ptype_loc = loc } as type_decl) =
       core_type_of_decl ~options ~path type_decl in
   let out_var =
     pvar (Ppx_deriving.mangle_type_decl (`Prefix "compare") type_decl) in
-  (* Capture type in helper module outside Ppx_deriving_runtime wrapper (added by sanitize).
-     Required for to_int constraint in variant type wildcard_case if the type name
-     conflicts with a Stdlib type from Ppx_deriving_runtime (e.g. bool in test).
-     In that case we must refer to the type being declared, not the one opened by Ppx_deriving_runtime. *)
-  let helper_type =
-    Type.mk ~loc ~attrs:[Ppx_deriving.attr_warning [%expr "-unused-type-declaration"]]
-      ~params:type_decl.ptype_params
-      ~manifest:(Ppx_deriving.core_type_of_type_decl type_decl)
-      (mkloc "t" loc)
-  in
   let comparator_with_helper =
     [%expr let module Ppx_deriving_ord_helper = struct [%%i Str.type_ Nonrecursive [helper_type]] end in
            [%e Ppx_deriving.sanitize ~quoter (eta_expand (polymorphize comparator))]]

src_test/eq/test_deriving_eq.cppo.ml

@@ -131,6 +131,8 @@ and 'a poly_abs_custom = 'a
 module List = struct
   type 'a t = [`Cons of 'a | `Nil]
   [@@deriving eq]
+  type 'a u = Cons of 'a | Nil
+  [@@deriving eq]
 end
 type 'a std_clash = 'a List.t option
 [@@deriving eq]

src_test/ord/test_deriving_ord.cppo.ml

@@ -158,6 +158,8 @@ and 'a poly_abs_custom = 'a
 module List = struct
   type 'a t = [`Cons of 'a | `Nil]
   [@@deriving ord]
+  type 'a u = Cons of 'a | Nil
+  [@@deriving ord]
 end
 type 'a std_clash = 'a List.t option
 [@@deriving ord]