fix theory combination for LRA

src/arith/sidekick_arith.ml

@@ -50,6 +50,8 @@ module type RATIONAL = sig
 
   val minus_infinity : t
 
+  val of_bigint : bigint -> t
+
   val is_real : t -> bool
   (** A proper real, not nan/infinity *)
 

src/base-solver/sidekick_base_solver.ml

@@ -98,6 +98,7 @@ module Th_lra = Sidekick_arith_lra.Make(struct
   let mk_bool = T.bool
 
   let rec view_as_lra t = match T.view t with
+    | T.LIA (Arith_const i) -> LRA.LRA_const (Q.of_bigint i)
     | T.LRA l ->
       let open Base_types in
       let module LRA = Sidekick_arith_lra in

src/lra/sidekick_arith_lra.ml

@@ -630,11 +630,13 @@ module Make(A : ARG) : S with module A = A = struct
   (* look for subterms of type Real, for they will need theory combination *)
   let on_subterm (self:state) _ (t:T.t) : unit =
     Log.debugf 50 (fun k->k "(@[lra.cc-on-subterm@ %a@])" T.pp t);
-    if A.has_ty_real t &&
-       not (T.Tbl.mem self.needs_th_combination t) then (
-      Log.debugf 5 (fun k->k "(@[lra.needs-th-combination@ %a@])" T.pp t);
-      T.Tbl.add self.needs_th_combination t ()
-    )
+    match A.view_as_lra t with
+    | LRA_other _ when not (A.has_ty_real t) -> ()
+    | _ ->
+      if not (T.Tbl.mem self.needs_th_combination t) then (
+        Log.debugf 5 (fun k->k "(@[lra.needs-th-combination@ %a@])" T.pp t);
+        T.Tbl.add self.needs_th_combination t ()
+      )
 
   let create_and_setup si =
     Log.debug 2 "(th-lra.setup)";