From 7d8f9472d89cd275789ba28831d24f95d38e96c8 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sun, 14 Mar 2021 19:51:10 +0000
Subject: [PATCH] hidden: Do not report moves to players seeing a Displaced
 occultation

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 src/pcrender.rs | 13 +++++++++++++
 src/prelude.rs  |  1 +
 2 files changed, 14 insertions(+)

diff --git a/src/pcrender.rs b/src/pcrender.rs
index 02e96ed0..08928c56 100644
--- a/src/pcrender.rs
+++ b/src/pcrender.rs
@@ -41,6 +41,19 @@ impl PieceRenderInstructions {
                              op: PieceUpdateOp<(),()>
   ) -> Option<PieceUpdateOp<PreparedPieceState, ZLevel>>
   {
+    use PieceUpdateOp::*;
+    use PriOcculted::*;
+    if matches_doesnot!(
+      op,
+      = Move(_) | SetZLevel(_),
+      ! Delete() | Insert(_) | Modify(_) | ModifyQuiet(_),
+    ) {
+      match self.occulted {
+        Visible | Occulted => (),
+        Displaced(..) => return None,
+      }
+    }
+
     let op = op.try_map(
       |()|{
         let ns = self.prep_piecestate(ioccults, gpc, ipc)?;
diff --git a/src/prelude.rs b/src/prelude.rs
index bc6c8d5a..71722f7d 100644
--- a/src/prelude.rs
+++ b/src/prelude.rs
@@ -103,6 +103,7 @@ pub use crate::dbgc;
 pub use crate::{deref_to_field, deref_to_field_mut};
 pub use crate::ensure_eq;
 pub use crate::from_instance_lock_error;
+pub use crate::matches_doesnot;
 pub use crate::trace_dbg;
 
 pub use crate::accounts::loaded_acl::{self, EffectiveACL, LoadedAcl, PermSet};
-- 
2.30.2