Simplify types before analyzing call structure; 2 more tests compile.

src/boot/me/semant.ml

@@ -1951,7 +1951,7 @@ let call_args_referent_type
       Il.ScalarTy (Il.AddrTy Il.OpaqueTy)
     |]
   in
-    match callee_ty with
+    match simplified_ty callee_ty with
         Ast.TY_fn (tsig, taux) ->
           call_args_referent_type_full
             cx.ctxt_abi
@@ -1961,7 +1961,9 @@ let call_args_referent_type
             (if taux.Ast.fn_is_iter then (iterator_arg_rtys()) else [||])
             indirect_arg_rtys
 
-      | _ -> bug cx "Semant.call_args_referent_type on non-callable type"
+      | _ -> bug cx
+          "Semant.call_args_referent_type on non-callable type %a"
+            Ast.sprintf_ty callee_ty
 ;;
 
 let indirect_call_args_referent_type

src/boot/me/trans.ml

@@ -3376,7 +3376,7 @@ let trans_visitor
             (oper_str operand)
 
   and ty_arg_slots (ty:Ast.ty) : Ast.slot array =
-    match ty with
+    match simplified_ty ty with
         Ast.TY_fn (tsig, _) -> tsig.Ast.sig_input_slots
       | _ -> bug () "Trans.ty_arg_slots on non-callable type: %a"
           Ast.sprintf_ty ty
@@ -4047,7 +4047,7 @@ let trans_visitor
           Some params -> params
         | None -> [| |]
     in
-      match ty with
+      match simplified_ty ty with
           Ast.TY_fn _ ->
             let (dst_cell, _) = trans_lval_maybe_init init dst in
             let fn_ptr =