From 7c1564f7b53d7bb19783d4d505a998f28626cdb2 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Fri, 19 Mar 2021 01:18:29 +0000
Subject: [PATCH] clock: Prevent both users being the same

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 src/clock.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/clock.rs b/src/clock.rs
index 228dd351..d5caa241 100644
--- a/src/clock.rs
+++ b/src/clock.rs
@@ -73,6 +73,11 @@ impl From<User> for u8 {
   fn from(user: User) -> u8 { user.0 as u8 }
 }
 
+impl std::ops::Not for User {
+  type Output = User;
+  fn not(self) -> User { User(! self.0) }
+}
+
 // ==================== state ====================
 
 #[derive(Debug,Clone,Serialize,Deserialize)]
@@ -425,6 +430,10 @@ impl PieceTrait for Clock {
         if let Some(_gpl) = gs.players.get(state.users[user].player) {
           throw!(OE::BadPieceStateForOperation);
         }
+        if state.users[! user].player == player {
+          // todo: some more useful per-player message
+          throw!(OE::BadPieceStateForOperation);
+        }
         state.users[user].player = player;
       },
       "unclaim-x" | "unclaim-y" => {
-- 
2.30.2