Fix an issue with nested parentheses in type patterns (#634)

Something like bool(((('b)))) wouldn't work, and even though it's
unlikely anyone would want to write this, there's no particular reason it
should fail.

src/lib/initial_check.ml

@@ -545,6 +545,7 @@ let rec to_ast_typ_pat ctx (P.ATyp_aux (aux, l)) =
   | P.ATyp_app (P.Id_aux (P.Id "bool", il), typs) ->
       TP_aux (TP_app (Id_aux (Id "atom_bool", il), List.map (to_ast_typ_pat ctx) typs), l)
   | P.ATyp_app (f, typs) -> TP_aux (TP_app (to_ast_id ctx f, List.map (to_ast_typ_pat ctx) typs), l)
+  | P.ATyp_parens atyp -> to_ast_typ_pat ctx atyp
   | _ -> raise (Reporting.err_typ l "Unexpected type in type pattern")
 
 let is_wild_fpat = function P.FP_aux (P.FP_wild, _) -> true | _ -> false

test/typecheck/pass/type_pat_parens.sail

@@ -0,0 +1,9 @@
+default Order dec
+
+$include <prelude.sail>
+
+val main : unit -> unit
+
+function main() = {
+  let _ as bool((((('b))))) = true;
+}