Fix nested object get and set not working in res files

Makefile

@@ -21,7 +21,7 @@ dev:
 
 .PHONY: test
 test:
-	opam exec -- dune runtest -p melange,reactjs-jsx-ppx
+	opam exec -- dune runtest -p melange,reactjs-jsx-ppx,rescript-syntax
 
 .PHONY: opam-create-switch
 opam-create-switch: ## Create opam switch

rescript-syntax/ppx_rescript_compat/ppx_rescript_compat.ml

@@ -47,10 +47,11 @@ let expr_mapper (self : mapper) (expr : Parsetree.expression) =
             args;
       }
   | Pexp_send
-      ( ({ pexp_desc = Pexp_apply _ | Pexp_ident _; pexp_loc; _ } as subexpr),
+      ( ({ pexp_desc = Pexp_apply _ | Pexp_ident _ | Pexp_send _; pexp_loc; _ } as subexpr),
         arg ) ->
       (* ReScript removed the OCaml object system and abuses `Pexp_send` for
          `obj##property`. Here, we make that conversion. *)
+      let subexpr = self.expr self subexpr in
       {
         expr with
         pexp_desc =

test/rescript-syntax/dune

@@ -0,0 +1,3 @@
+(cram
+ (package rescript-syntax)
+ (deps %{bin:melc} %{bin:rescript_syntax}))

test/rescript-syntax/gh489.t

@@ -0,0 +1,42 @@
+Repro for GitHub issue 489, first try setting values in nested objects with OCaml syntax
+
+  $ cat > foo.ml <<EOF
+  > type person = < age :int [@bs.set ] > Js.t
+  > type entry = < person :person [@bs.set ] > Js.t
+  > external entry : entry = "entry"[@@bs.val ]
+  > let () = ((entry ## person) ##  age) #= 99
+  > EOF
+  $ melc foo.ml
+  // Generated by Melange
+  'use strict';
+
+
+  entry.person.age = 99;
+
+  /*  Not a pure module */
+
+Now let's try with ReScript syntax
+
+  $ cat > foo.res <<EOF
+  > type person = {@set "age": int}
+  > type entry = {@set "person": person}
+  > type deep = {@set "deep": entry}
+  > @val external deep: deep = "deep"
+  > deep["deep"]["person"]["age"] = 99
+  $ rescript_syntax -print=ml foo.res
+  type nonrec person = < age: int [@set ]  >  Js.t
+  type nonrec entry = < person: person [@set ]  >  Js.t
+  type nonrec deep = < deep: entry [@set ]  >  Js.t
+  external deep : deep = "deep"[@@val ]
+  ;;(((deep ## deep) ## person) ## age) #= 99
+
+  $ rescript_syntax -print=ml foo.res > foo.ml
+
+  $ melc foo.ml
+  // Generated by Melange
+  'use strict';
+
+
+  deep.deep.person.age = 99;
+
+  /*  Not a pure module */