From 2def06b98f94a6c203acefc555fa42cfc7142733 Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Thu, 28 May 2020 17:55:53 -0400
Subject: [PATCH] fix #1076

---
 irc/client.go   | 2 +-
 irc/monitor.go  | 6 ++----
 irc/nickname.go | 6 +++++-
 irc/server.go   | 2 +-
 4 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/irc/client.go b/irc/client.go
index 4445ad5c..b2b2a0e6 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -1333,7 +1333,7 @@ func (client *Client) destroy(session *Session) {
 
 	// alert monitors
 	if registered {
-		client.server.monitorManager.AlertAbout(client, false)
+		client.server.monitorManager.AlertAbout(details.nick, details.nickCasefolded, false)
 	}
 	// clean up monitor state
 	client.server.monitorManager.RemoveAll(client)
diff --git a/irc/monitor.go b/irc/monitor.go
index b053b21b..e9cde7c4 100644
--- a/irc/monitor.go
+++ b/irc/monitor.go
@@ -25,9 +25,7 @@ func (mm *MonitorManager) Initialize() {
 }
 
 // AlertAbout alerts everyone monitoring `client`'s nick that `client` is now {on,off}line.
-func (manager *MonitorManager) AlertAbout(client *Client, online bool) {
-	cfnick := client.NickCasefolded()
-	nick := client.Nick()
+func (manager *MonitorManager) AlertAbout(nick, cfnick string, online bool) {
 	var watchers []*Client
 	// safely copy the list of clients watching our nick
 	manager.RLock()
@@ -42,7 +40,7 @@ func (manager *MonitorManager) AlertAbout(client *Client, online bool) {
 	}
 
 	for _, mClient := range watchers {
-		mClient.Send(nil, client.server.name, command, mClient.Nick(), nick)
+		mClient.Send(nil, mClient.server.name, command, mClient.Nick(), nick)
 	}
 }
 
diff --git a/irc/nickname.go b/irc/nickname.go
index 9c54120f..20f493f9 100644
--- a/irc/nickname.go
+++ b/irc/nickname.go
@@ -89,7 +89,11 @@ func performNickChange(server *Server, client *Client, target *Client, session *
 	}
 
 	if target.Registered() {
-		client.server.monitorManager.AlertAbout(target, true)
+		newCfnick := target.NickCasefolded()
+		if newCfnick != details.nickCasefolded {
+			client.server.monitorManager.AlertAbout(details.nick, details.nickCasefolded, false)
+			client.server.monitorManager.AlertAbout(assignedNickname, newCfnick, true)
+		}
 		target.nickTimer.Touch(rb)
 	} // else: these will be deferred to the end of registration (see #572)
 	return nil
diff --git a/irc/server.go b/irc/server.go
index bce3a101..17a279a1 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -271,7 +271,7 @@ func (server *Server) tryRegister(c *Client, session *Session) (exiting bool) {
 
 	// count new user in statistics
 	server.stats.Register()
-	server.monitorManager.AlertAbout(c, true)
+	server.monitorManager.AlertAbout(c.Nick(), c.NickCasefolded(), true)
 
 	server.playRegistrationBurst(session)
 	return false