From: Bennet Bleßmann <bb-github@t-online.de>
Date: Sun, 7 Jul 2024 12:37:28 +0000 (+0200)
Subject: check that we don't attempt to un-drop while evacuating
X-Git-Tag: v0.10.0~127^2~3
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=a0d790445d65f7d960656a7357b8f13b35540f58;p=scryer-prolog.git

check that we don't attempt to un-drop while evacuating
---

diff --git a/src/machine/loader.rs b/src/machine/loader.rs
index 88666330..0dfdfad2 100644
--- a/src/machine/loader.rs
+++ b/src/machine/loader.rs
@@ -304,11 +304,15 @@ impl<'a> LoadState<'a> for LiveLoadAndMachineState<'a> {
 
     #[inline(always)]
     fn evacuate(mut loader: Loader<'a, Self>) -> Result<Self::Evacuable, SessionError> {
+        if loader.payload.load_state.get_tag() != ArenaHeaderTag::Dropped {
         loader
             .payload
             .load_state
             .set_tag(ArenaHeaderTag::InactiveLoadState);
         Ok(loader.payload.load_state)
+        } else {
+            unreachable!("we never evacuate after dropping")
+        }
     }
 
     #[inline(always)]