From d5c4342bceadc4d3c3997986cb48f3bd4235e8f8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Helleu?= <flashcode@flashtux.org>
Date: Thu, 21 Jul 2022 11:16:50 +0200
Subject: [PATCH] irc: fix display of TOPIC message with an empty trailing
 parameter

---
 ChangeLog.adoc                               | 2 +-
 src/plugins/irc/irc-protocol.c               | 7 +++++--
 tests/unit/plugins/irc/test-irc-protocol.cpp | 5 +++++
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/ChangeLog.adoc b/ChangeLog.adoc
index 55f0fefd7..b07111936 100644
--- a/ChangeLog.adoc
+++ b/ChangeLog.adoc
@@ -26,7 +26,7 @@ New features::
 Bug fixes::
 
   * irc: fix duplicated channels in autojoin option when autojoin_dynamic is enabled (issue #1795)
-  * irc: fix display of QUIT message with an empty trailing parameter (issue #1797)
+  * irc: fix display of TOPIC and QUIT messages with an empty trailing parameter (issue #1797)
   * relay: fix parsing of IRC messages received from clients (issue #1796)
 
 [[v3.6]]
diff --git a/src/plugins/irc/irc-protocol.c b/src/plugins/irc/irc-protocol.c
index 67941d6bb..6ebd0caf4 100644
--- a/src/plugins/irc/irc-protocol.c
+++ b/src/plugins/irc/irc-protocol.c
@@ -3258,7 +3258,7 @@ IRC_PROTOCOL_CALLBACK(topic)
     if (ptr_channel)
         irc_channel_join_smart_filtered_unmask (ptr_channel, nick);
 
-    if (str_topic)
+    if (str_topic && str_topic[0])
     {
         topic_color = irc_color_decode (
             str_topic,
@@ -3361,7 +3361,10 @@ IRC_PROTOCOL_CALLBACK(topic)
     }
 
     if (ptr_channel)
-        irc_channel_set_topic (ptr_channel, str_topic);
+    {
+        irc_channel_set_topic (ptr_channel,
+                               (str_topic && str_topic[0]) ? str_topic : NULL);
+    }
 
     if (str_topic)
         free (str_topic);
diff --git a/tests/unit/plugins/irc/test-irc-protocol.cpp b/tests/unit/plugins/irc/test-irc-protocol.cpp
index 838a0cb8c..9d3c34864 100644
--- a/tests/unit/plugins/irc/test-irc-protocol.cpp
+++ b/tests/unit/plugins/irc/test-irc-protocol.cpp
@@ -1966,6 +1966,11 @@ TEST(IrcProtocolWithServer, topic)
     CHECK_CHAN("-- alice has unset topic for #test");
     POINTERS_EQUAL(NULL, ptr_channel->topic);
 
+    /* empty topic (with empty trailing parameter) */
+    RECV(":alice!user@host TOPIC #test :");
+    CHECK_CHAN("-- alice has unset topic for #test");
+    POINTERS_EQUAL(NULL, ptr_channel->topic);
+
     /* new topic */
     RECV(":alice!user@host TOPIC #test :new topic ");
     CHECK_CHAN("-- alice has changed topic for #test to \"new topic \"");