From ab031537ffbf2f792c9015830e8f29452dbf0de8 Mon Sep 17 00:00:00 2001
From: Tobias Mock <mail@tmock.de>
Date: Fri, 11 Oct 2024 22:04:39 +0200
Subject: [PATCH] Fix usage of applied functors behind signatures

---
 lib/module.ml                             |  6 ++++++
 lib/monomorph_tree.ml                     |  4 +++-
 test/modules.t/hidden_functor_app.smu     | 10 ++++++++++
 test/modules.t/use_hidden_functor_app.smu |  3 +++
 4 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 test/modules.t/hidden_functor_app.smu
 create mode 100644 test/modules.t/use_hidden_functor_app.smu

diff --git a/lib/module.ml b/lib/module.ml
index a3d88f1..ea61347 100644
--- a/lib/module.ml
+++ b/lib/module.ml
@@ -390,6 +390,12 @@ let rec add_to_env env foreign (mname, m) =
                 if not (Hashtbl.mem tbl name) then
                   (* Add decl to table *)
                   Hashtbl.add tbl name decl
+            | Mapplied_functor (loc, key, p, m) -> (
+                (* [register_applied_functor] adds the types to the decl table
+                   so they are readable later on *)
+                match register_applied_functor env loc key p m with
+                | Ok _ -> ()
+                | Error () -> raise (Error (loc, "Cannot apply functor")))
             | _ -> ())
           m.i;
         env
diff --git a/lib/monomorph_tree.ml b/lib/monomorph_tree.ml
index 3a67eb0..558aae6 100644
--- a/lib/monomorph_tree.ml
+++ b/lib/monomorph_tree.ml
@@ -280,7 +280,9 @@ let rec cln ss p = function
             | Dabstract (Some dkind) -> cln_dkind dkind
           in
           cln_dkind decl.kind
-      | None -> failwith "Internal Error: Tconstr not available")
+      | None ->
+          failwith
+            ("Internal Error: Tconstr " ^ Path.show name ^ " not available"))
 
 and cln_kind ss p = function
   | Simple -> Simple
diff --git a/test/modules.t/hidden_functor_app.smu b/test/modules.t/hidden_functor_app.smu
new file mode 100644
index 0000000..08b9695
--- /dev/null
+++ b/test/modules.t/hidden_functor_app.smu
@@ -0,0 +1,10 @@
+signature {
+  val do : () -> unit
+}
+
+module stbl = hashtbl/make(string)
+
+fun do() {
+  let _ : stbl/t[int] = stbl/create(16)
+  ()
+}
diff --git a/test/modules.t/use_hidden_functor_app.smu b/test/modules.t/use_hidden_functor_app.smu
new file mode 100644
index 0000000..1aa8b19
--- /dev/null
+++ b/test/modules.t/use_hidden_functor_app.smu
@@ -0,0 +1,3 @@
+import hidden_functor_app
+
+hidden_functor_app/do()