fix: promote parameters that are bounded with function types (#4617)

so that execution can observe

fixes #4616

Changelog.md

@@ -1,5 +1,11 @@
 # Motoko compiler changelog
 
+## 0.11.3 (2024-07-XX)
+
+* motoko (`moc`)
+
+  * bugfix: Corrects the interpreter (and compiler) to recognise certain type parameters as callable function types (#4617).
+
 ## 0.11.2 (2024-07-06)
 
 * motoko (`moc`)

src/codegen/compile.ml

@@ -10577,7 +10577,7 @@ and compile_prim_invocation (env : E.t) ae p es at =
   begin match p, es with
   (* Calls *)
   | CallPrim _, [e1; e2] ->
-    let sort, control, _, arg_tys, ret_tys = Type.as_func e1.note.Note.typ in
+    let sort, control, _, arg_tys, ret_tys = Type.(as_func (promote e1.note.Note.typ)) in
     let n_args = List.length arg_tys in
     let return_arity = match control with
       | Type.Returns -> List.length ret_tys

src/mo_types/type.ml

@@ -657,7 +657,7 @@ let as_func_sub default_s default_arity t = match promote t with
 let as_mono_func_sub t = match promote t with
   | Func (_, _, [], ts1, ts2) -> seq ts1, seq ts2
   | Non -> Any, Non
-  | _ -> invalid "as_func_sub"
+  | _ -> invalid "as_mono_func_sub"
 let as_async_sub s default_scope t = match promote t with
   | Async (s0, t1, t2) when s = s0 -> (t1, t2)
   | Non -> default_scope, Non (* TBR *)

src/mo_values/call_conv.ml

@@ -22,7 +22,7 @@ let async_cc s n m = { sort = Shared s; control = Promises; n_args = n; n_res =
 let replies_cc s n m = { sort = Shared s; control = Replies; n_args = n; n_res = m}
 
 let call_conv_of_typ typ =
-  match typ with
+  match promote typ with
   | Func (sort, control, tbds, dom, res) ->
     { sort; control; n_args = List.length dom; n_res = List.length res }
   | Non ->

test/run/contra-bound.mo

@@ -0,0 +1,3 @@
+func foo<T, K <: T -> ()>(k : K, v : T) = k v;
+
+foo<Nat, Int -> ()>(func(i : Int) {}, 1);