Reject empty args in dynamic fun_apply (#15254)

Author: gldubc

lib/elixir/lib/module/types/descr.ex

@@ -1442,12 +1442,10 @@ defmodule Module.Types.Descr do
     static? = fun_dynamic == nil and Enum.all?(arguments, fn arg -> not gradual?(arg) end)
     arity = length(arguments)
 
-    with {:ok, domain, static_arrows, dynamic_arrows} <-
+    with false <- Enum.any?(arguments, &empty?/1),
+         {:ok, domain, static_arrows, dynamic_arrows} <-
            fun_normalize_both(fun_static, fun_dynamic, arity) do
       cond do
-        Enum.any?(arguments, &empty?/1) ->
-          {:badarg, domain_to_flat_args(domain, arity)}
-
         # The domain here is the extended gradual domain computed by
         # fun_normalize_both/3. If the argument does not satisfy it, we
         # check compatibility before rejecting.
@@ -1498,6 +1496,9 @@ defmodule Module.Types.Descr do
              dynamic(fun_apply_static(arguments, dynamic_arrows))
            )}
       end
+    else
+      true -> {:badarg, arguments}
+      error -> error
     end
   end
 

lib/elixir/test/elixir/module/types/descr_test.exs

@@ -1214,6 +1214,7 @@ defmodule Module.Types.DescrTest do
       assert fun_apply(dynamic_fun([integer()], atom()), [float()]) == {:ok, dynamic()}
       assert fun_apply(dynamic_fun([integer()], atom()), [term()]) == {:ok, dynamic()}
       assert fun_apply(dynamic_fun([integer()], none()), [integer()]) == {:ok, dynamic(none())}
+      assert fun_apply(dynamic(fun([integer()], integer())), [none()]) == {:badarg, [none()]}
       assert fun_apply(dynamic_fun([integer()], term()), [integer()]) == {:ok, dynamic()}
 
       # Dynamic return and dynamic args