fix: repro and fix for issue #5618

Changelog.md

@@ -2,6 +2,8 @@
 
 * motoko (`moc`)
 
+  * Fix for #5618 (compiling dotted `await`s) (#5622).
+
   * Improved type inference of the record update syntax (#5625).
 
   * New flag `--error-recovery` to enable reporting of multiple syntax errors (#5632).

src/mo_def/syntax.ml

@@ -391,11 +391,16 @@ let contextual_dot_args e1 e2 dot_note =
   let arity = match dot_note.note.note_typ with
     | T.Func(_, _, _, args, _) -> List.length args
     | _ -> raise (Invalid_argument "non-function type in contextual dot note") in
+  let effect eff =
+    match (e1.note.note_eff, eff) with
+    | T.Triv, T.Triv -> T.Triv
+    | _, _ -> T.Await
+  in
   let args = match e2 with
     | { it = TupE []; at; note = { note_eff;_ } } ->
-       { it = e1.it; at; note = { note_eff; note_typ = e1.note.note_typ } }
+       { it = e1.it; at; note = { note_eff = effect note_eff; note_typ = e1.note.note_typ } }
     | { it = TupE exps; at; note = { note_eff; note_typ = T.Tup ts } } when arity <> 2 ->
-       { it = TupE (e1::exps); at; note = { note_eff; note_typ = T.Tup (e1.note.note_typ::ts) } }
+       { it = TupE (e1::exps); at; note = { note_eff = effect note_eff; note_typ = T.Tup (e1.note.note_typ::ts) } }
     | { at; note = { note_eff; _ }; _ } ->
-       { it = TupE ([e1; e2]); at; note = { note_eff; note_typ = T.Tup ([e1.note.note_typ; e2.note.note_typ]) } }
+       { it = TupE ([e1; e2]); at; note = { note_eff = effect note_eff; note_typ = T.Tup ([e1.note.note_typ; e2.note.note_typ]) } }
   in args

src/mo_frontend/typing.ml

@@ -2667,8 +2667,11 @@ and infer_callee env exp =
         mk_error env
       | Ok { module_name; path; func_ty; inst; _ } ->
         note := Some path;
-        if not env.pre then
+        if not env.pre then begin
           check_exp env func_ty path;
+          let note_eff = A.infer_effect_exp exp in
+          exp.note <- {note_typ = exp.note.note_typ; note_eff}
+        end;
         func_ty, Some (exp1, t1, id.it, inst)
      end
   | _ ->

test/run-drun/await-dot.mo

@@ -0,0 +1,11 @@
+persistent actor {
+
+   module Nat {
+     public func id(self : Nat) : Nat { self };
+   };
+
+  public func go () {
+     ignore (await (async 1)).id() == 1;
+  }
+
+}

test/run-drun/ok/await-dot.drun-run.ok

@@ -0,0 +1,2 @@
+ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
+ingress Completed: Reply: 0x4449444c0000