Fix the inifinite loop in variant expansions.

Get rid of all the complicated and useless code and just
use a reinterpret cast, since all polymorphic variants
have the same representation.

src/compiler/flx_core/flx_beta.ml

@@ -321,7 +321,13 @@ print_endline "Type list index returned None";
       begin match bbdcl with
       | Flx_bbdcl.BBDCL_type_alias (bvs, alias) ->
        let alias = Flx_btype_subst.tsubst sr bvs ts alias in
+(*
+print_endline ("Flx_beta: Alias " ^ bsym.id ^"<"^string_of_int index^">" ^ "["^String.concat "," (List.map Flx_btype.st ts) ^"] after substitution " ^ Flx_btype.st alias);
+*)
        let alias = beta_reduce' calltag counter bsym_table sr  depth ((t,depth)::termlist) alias in
+(*
+print_endline ("Flx_beta: Alias " ^ bsym.id ^"<"^string_of_int index^">" ^ "["^String.concat "," (List.map Flx_btype.st ts) ^"] after beta-reduction " ^ Flx_btype.st alias);
+*)
        (* NOTE: Alias viewification performed here .. not sure it would ever be used .. *)
        begin match m with 
        | `P
@@ -421,13 +427,19 @@ print_endline ("Beta-reducing typeop " ^ op ^ ", type=" ^ sbt bsym_table t);
      btyp_variant (List.combine ss (List.map br ls))
 
   | BTYP_polyvariant ts ->
+    (* NO DEPTH INCREASE FOR ALIAS EXPANSION *)
+    let br' t = beta_reduce' calltag counter bsym_table sr depth termlist t in
     let ctors = List.fold_left (fun acc term -> match term with
-      | `Ctor (s,t) -> (s,br t)::acc
-      | `Base t -> match br t with
+      | `Ctor (s,t) -> (s,br t)::acc (* depth expansion *)
+      | `Base t -> match br' t with (* No depth expansion *)
         | BTYP_variant ts -> ts @ acc
         | _ -> print_endline ("Reduction of polyvariant failed"); assert false
      ) [] ts
-    in btyp_variant ctors
+    in 
+    let t = btyp_variant ctors in
+    (* print_endline ("Reduced polyvariant type " ^ Flx_btype.st t); *)
+    t
+
 (*
     btyp_polyvariant (List.map (fun k -> match k with
       | `Ctor (s,t) -> `Ctor (s, br t)

src/compiler/flx_core/flx_type_fun.ml

@@ -73,6 +73,9 @@ print_endline ("Type apply " ^ Flx_btype.st f ^ " to " ^ Flx_btype.st arg);
       begin match bbdcl with
       | Flx_bbdcl.BBDCL_type_alias (bvs, alias) ->
        let salias = Flx_btype_subst.tsubst sr bvs ts alias in
+(*
+print_endline ("Alias " ^ bsym.id ^ "["^String.concat "," (List.map Flx_btype.st ts) ^"] after substitution " ^ Flx_btype.st salias);
+*)
        type_apply beta_reduce' calltag counter bsym_table sr depth termlist salias arg
       | _ ->  assert false
       end

src/compiler/flx_frontend/flx_xcoerce.ml

@@ -98,6 +98,9 @@ and unique_check ls =
     ls
 
 and variant_coercion new_table bsym_table counter parent remap ((srcx,srct) as srce) dstt ls rs sr =
+    let e = remap parent srce in
+    bexpr_reinterpret_cast (e,dstt)
+(*
   let coerce parent e dstt = expand_coercion new_table bsym_table counter parent remap e dstt sr in
   if debug then 
   print_endline ("Variant coercion " ^ Flx_btype.st srct ^ " => " ^ Flx_btype.st dstt); 
@@ -254,7 +257,7 @@ print_endline ("MINIMISED dstt = " ^ Flx_btype.st dstt);
       remap parent result
     end
   end
-
+*)
 
 and record_coercion new_table bsym_table counter parent remap ((srcx,srct) as srce) dstt ls rs sr =
   let coerce parent e dstt = expand_coercion new_table bsym_table counter parent remap e dstt sr in
@@ -557,9 +560,7 @@ and process_expr new_table bsym_table counter parent sr expr =
   match e with
   (* coercion with argument free of reducible coercions *)
   | BEXPR_coerce ((srcx,srct) as srce,dstt),_ -> 
-    (*
-    print_endline ("Examining coercion " ^ Flx_print.sbe bsym_table e );
-    *)
+    (* print_endline ("Examining coercion " ^ Flx_print.sbe bsym_table e ); *)
     let e' = 
       try   
         expand_coercion new_table bsym_table counter parent remap srce dstt sr 
@@ -615,6 +616,9 @@ print_endline ("Processing function " ^ Flx_bsym.id bsym);
   not be used, but cannot be eliminated in case they're used.
 *)
 let expand_coercions syms bsym_table = 
+(*
+print_endline ("EXPAND COERCIONS: START");
+*)
   let new_table = Flx_bsym_table.create_fresh () in
   Flx_bsym_table.iter 
    (fun i parent bsym -> process_entry new_table bsym_table syms.Flx_mtypes2.counter parent i bsym)