Fix issue with arrays and creation of recursive values.

Not clear where the reference to ocaml/ocaml#6939 comes from, as that issue is about unboxed float arrays.

See https://forum.rescript-lang.org/t/recursive-type-usage-problem/3717

Author: cristianoc

jscomp/ml/rec_check.ml

@@ -236,10 +236,7 @@ let rec expression : Env.env -> Typedtree.expression -> Use.t =
       let arg env (_, eo) = option expression env eo in
       Use.(join (inspect (expression env e)) (inspect (list arg env args)))
   | Texp_tuple exprs -> Use.guard (list expression env exprs)
-  | Texp_array exprs ->
-      (* This is counted as a use, because constructing a generic array
-         involves inspecting the elements (PR#6939). *)
-      Use.inspect (list expression env exprs)
+  | Texp_array exprs -> Use.guard (list expression env exprs)
   | Texp_construct (_, desc, exprs) ->
       let access_constructor =
         match desc.cstr_tag with

jscomp/test/build.ninja

@@ -0,0 +1,19 @@
+'use strict';
+
+var Caml_obj = require("../../lib/js/caml_obj.js");
+
+var vicky = {};
+
+var teacher = {};
+
+Caml_obj.update_dummy(vicky, {
+      taughtBy: teacher
+    });
+
+Caml_obj.update_dummy(teacher, {
+      students: [vicky]
+    });
+
+exports.vicky = vicky;
+exports.teacher = teacher;
+/* No side effect */

jscomp/test/rec_array_test.js

@@ -0,0 +1,5 @@
+type rec student = {taughtBy: teacher}
+and teacher = {students: array<student>}
+
+let rec vicky = { taughtBy: teacher } 
+and teacher = {students: [vicky]}

jscomp/test/rec_array_test.res

@@ -38300,10 +38300,7 @@ let rec expression : Env.env -> Typedtree.expression -> Use.t =
       let arg env (_, eo) = option expression env eo in
       Use.(join (inspect (expression env e)) (inspect (list arg env args)))
   | Texp_tuple exprs -> Use.guard (list expression env exprs)
-  | Texp_array exprs ->
-      (* This is counted as a use, because constructing a generic array
-         involves inspecting the elements (PR#6939). *)
-      Use.inspect (list expression env exprs)
+  | Texp_array exprs -> Use.guard (list expression env exprs)
   | Texp_construct (_, desc, exprs) ->
       let access_constructor =
         match desc.cstr_tag with

lib/4.06.1/unstable/js_compiler.ml

@@ -38300,10 +38300,7 @@ let rec expression : Env.env -> Typedtree.expression -> Use.t =
       let arg env (_, eo) = option expression env eo in
       Use.(join (inspect (expression env e)) (inspect (list arg env args)))
   | Texp_tuple exprs -> Use.guard (list expression env exprs)
-  | Texp_array exprs ->
-      (* This is counted as a use, because constructing a generic array
-         involves inspecting the elements (PR#6939). *)
-      Use.inspect (list expression env exprs)
+  | Texp_array exprs -> Use.guard (list expression env exprs)
   | Texp_construct (_, desc, exprs) ->
       let access_constructor =
         match desc.cstr_tag with

lib/4.06.1/unstable/js_playground_compiler.ml

@@ -212831,10 +212831,7 @@ let rec expression : Env.env -> Typedtree.expression -> Use.t =
       let arg env (_, eo) = option expression env eo in
       Use.(join (inspect (expression env e)) (inspect (list arg env args)))
   | Texp_tuple exprs -> Use.guard (list expression env exprs)
-  | Texp_array exprs ->
-      (* This is counted as a use, because constructing a generic array
-         involves inspecting the elements (PR#6939). *)
-      Use.inspect (list expression env exprs)
+  | Texp_array exprs -> Use.guard (list expression env exprs)
   | Texp_construct (_, desc, exprs) ->
       let access_constructor =
         match desc.cstr_tag with