review

middle_end/flambda2/datalog/cursor.ml

@@ -15,6 +15,8 @@
 
 open Datalog_imports
 
+(* Note: we don't use [with_name] here to avoid the extra indirection during
+   execution. *)
 type vm_action =
   | Unless :
       ('t, 'k, 'v) Trie.is_trie

middle_end/flambda2/datalog/datalog.ml

@@ -97,7 +97,8 @@ let rec bind_atom :
     =
  fun ~order post_level args iterators iterator_names ->
   match args, iterators, iterator_names with
-  | [], [], _ -> ()
+  | [], [], [] -> ()
+  | [], [], _ :: _ -> Misc.fatal_error "Too many names in [bind_atom]"
   | _, _, [] -> Misc.fatal_error "Missing names in [bind_atom]"
   | ( this_arg :: other_args,
       this_iterator :: other_iterators,

middle_end/flambda2/datalog/virtual_machine.ml

@@ -215,15 +215,15 @@ module Make (Iterator : Leapfrog.Iterator) = struct
         (_, nil) instruction =
      fun iterators refs instruction iterator_names ->
       match iterators, refs, iterator_names with
-      | [iterator], [r], name :: _ ->
+      | [iterator], [r], [name] ->
         open_ { value = iterator; name } { value = r; name = "_" } instruction
           dispatch
       | iterator :: (_ :: _ as iterators), r :: refs, name :: iterator_names ->
         loop iterators refs
           (open_ { value = iterator; name } { value = r; name = "_" }
              instruction dispatch)
           iterator_names
-      | _, _, [] ->
+      | _, _, [] | [_], [_], _ :: _ :: _ ->
         Misc.fatal_errorf "Incorrect number of names for iterators in [iterate]"
     in
     match rev_iterators with