From 55592b253f3dddb121c1072ca584e95c37729b6d Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Tue, 13 Oct 2020 18:04:24 +0000
Subject: [PATCH] Add some more docs

---
 src/libstore/build/worker.hh | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/libstore/build/worker.hh b/src/libstore/build/worker.hh
index 07c0c0f16..f8bacc514 100644
--- a/src/libstore/build/worker.hh
+++ b/src/libstore/build/worker.hh
@@ -11,6 +11,11 @@ namespace nix {
 class DerivationGoal;
 class SubstitutionGoal;
 
+/* Workaround for not being able to declare a something like
+
+     class SubstitutionGoal : public Goal;
+
+   even when Goal is a complete type; */
 GoalPtr upcast_goal(std::shared_ptr<SubstitutionGoal> subGoal);
 
 typedef std::chrono::time_point<std::chrono::steady_clock> steady_time_point;