Unsplat state before checkpoint to capture parameters

Function parameters were not always getting captured in the state when
checkpointing before a `try` block. Unsplatting right before
checkpoint ensures that the variables stick around.

Author: ashton314

lib/chorex.ex

@@ -576,6 +576,7 @@ defmodule Chorex do
           RuntimeMonitor.begin_checkpoint(state.config.monitor, barrier_token)
 
           # send state to monitor
+          unquote_splicing(unsplat_state(ctx))
           RuntimeMonitor.checkpoint_state(state.config.monitor, unquote(label), state)
 
           # func frame so that we get the right return value

test/broken_recover_test.exs

@@ -0,0 +1,75 @@
+defmodule BrokenRecoverTest do
+  use ExUnit.Case
+
+  import Chorex
+
+  defmodule HandyLogger do
+    use GenServer
+
+    @impl true
+    def init(_) do
+      {:ok, []}
+    end
+
+    @impl true
+    def handle_info({:log, msg}, state) do
+	  {:noreply, [msg | state]}
+    end
+
+    @impl true
+    def handle_call(:flush, _from, state) do
+	  {:reply, state, []}
+    end
+  end
+
+  defmodule Recover3TestChor do
+    defchor [Rec3Alice, Rec3Bob] do
+      def run(Rec3Alice.(lgr), Rec3Bob.(lgr)) do
+        try do
+          Rec3Alice.f(1 / 0) ~> Rec3Bob.(y)
+        rescue
+          Rec3Alice.log_failure(lgr)
+          Rec3Bob.log_failure(lgr)
+        end
+        Rec3Alice.(2 + 2) ~> Rec3Bob.(sum)
+        Rec3Bob.(sum)
+      end
+    end
+  end
+
+  defmodule MyRec3Alice do
+    use Recover3TestChor.Chorex, :rec3alice
+
+    @impl true
+    def f(a) do
+      a
+    end
+
+    @impl true
+    def log_failure(logger) do
+      send(logger, {:log, :failed})
+    end
+  end
+
+  defmodule MyRec3Bob do
+    use Recover3TestChor.Chorex, :rec3bob
+
+    @impl true
+    def log_failure(logger) do
+      send(logger, {:log, :failed})
+    end
+  end
+
+  test "failure-path2 with continuation" do
+    {:ok, l1} = GenServer.start(HandyLogger, nil)
+    {:ok, l2} = GenServer.start(HandyLogger, nil)
+    Logger.configure(level: :none) # suppress crash messages
+    # Note: parameter different
+    Chorex.start(Recover3TestChor.Chorex, %{Rec3Alice => MyRec3Alice, Rec3Bob => MyRec3Bob}, [l1, l2])
+
+    assert_receive {:chorex_return, Rec3Bob, 4}
+    assert [:failed] = GenServer.call(l1, :flush)
+    assert [:failed] = GenServer.call(l2, :flush)
+    Logger.configure(level: :all)
+  end
+end