From a879e756cf06ba9684eecd9296a787e7a724b87b Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Thu, 11 Mar 2021 19:24:51 +0000
Subject: [PATCH] hidden: pass a unique Generation into permute

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 src/hidden.rs | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/hidden.rs b/src/hidden.rs
index 8eb6fd25..cc469717 100644
--- a/src/hidden.rs
+++ b/src/hidden.rs
@@ -395,7 +395,8 @@ mod vpid {
                  occ: &mut Occultation,
                  gplayers: &mut GPlayers,
                  gpieces: &mut GPieces,
-                 ipieces: &IPieces) {
+                 ipieces: &IPieces,
+                 z_gen: Generation /* unique to this call */) {
     let new_notches = {
 
       let mut ilks: HashMap<OccultIlkId, (
@@ -854,14 +855,25 @@ mod recompute {
     }
     pub fn mark_dirty(&mut self, occid: OccId) { self.outdated.insert(occid); }
     pub fn implement(self,
-                     _gen: &mut Generation,
+                     gen: &mut Generation,
                      gplayers: &mut GPlayers,
                      gpieces: &mut GPieces,
                      goccults: &mut GameOccults,
                      ipieces: &IPieces) -> Implemented {
+      struct GenIncr<'g> { gen: &'g mut Generation, none_yet: Option<()>, }
+      impl GenIncr<'_> {
+        fn next(&mut self) -> Generation {
+          if self.none_yet.take().is_some() { self.gen.increment() }
+          let r = *self.gen;
+          self.gen.increment();
+          r
+        }
+      }
+      let mut gen = GenIncr { gen, none_yet: Some(()) };
+
       for occid in self.outdated {
         if let Some(occ) = goccults.occults.get_mut(occid) {
-          vpid::permute(occid, occ, gplayers, gpieces, ipieces);
+          vpid::permute(occid, occ, gplayers, gpieces, ipieces, gen.next());
         }
       }
 
-- 
2.30.2