Merge pull request #154 from gasche/4.05-support

make ppx_deriving 4.1 build under 4.05

opam

@@ -25,6 +25,7 @@ depends: [
   "ocamlbuild" {build}
   "ocamlfind"  {build & >= "1.6.0"}
   "cppo"       {build}
+  "cppo_ocamlbuild" {build}
   "ppx_tools"  {>= "4.02.3"}
   "result"
   "ounit"      {test}

src/ppx_deriving.cppo.ml

@@ -327,6 +327,9 @@ let free_vars_in_core_type typ =
       List.map free_in xs |> List.concat
     | { ptyp_desc = Ptyp_alias (x, name) } -> [name] @ free_in x
     | { ptyp_desc = Ptyp_poly (bound, x) } ->
+#if OCAML_VERSION >= (4, 05, 0)
+      let bound = List.map (fun y -> y.txt) bound in
+#endif
       List.filter (fun y -> not (List.mem y bound)) (free_in x)
     | { ptyp_desc = Ptyp_variant (rows, _, _) } ->
       List.map (
@@ -419,6 +422,11 @@ let binop_reduce x a b =
 
 let strong_type_of_type ty =
   let free_vars = free_vars_in_core_type ty in
+#if OCAML_VERSION >= (4, 05, 0)
+  (* give the location of the whole type to the introduced variables *)
+  let loc = { ty.ptyp_loc with loc_ghost = true } in
+  let free_vars = List.map (fun v -> mkloc v loc) free_vars in
+#endif
   Typ.force_poly @@ Typ.poly free_vars ty
 
 type deriver_options =