fix: stop using leftgrps table

src/chat.rs

@@ -3881,7 +3881,6 @@ pub async fn remove_contact_from_chat(
 
                     if contact_id == ContactId::SELF {
                         res?;
-                        set_group_explicitly_left(context, &chat.grpid).await?;
                     } else if let Err(e) = res {
                         warn!(
                             context,
@@ -3935,25 +3934,6 @@ async fn send_member_removal_msg(
     send_msg(context, chat.id, &mut msg).await
 }
 
-async fn set_group_explicitly_left(context: &Context, grpid: &str) -> Result<()> {
-    if !is_group_explicitly_left(context, grpid).await? {
-        context
-            .sql
-            .execute("INSERT INTO leftgrps (grpid) VALUES(?);", (grpid,))
-            .await?;
-    }
-
-    Ok(())
-}
-
-pub(crate) async fn is_group_explicitly_left(context: &Context, grpid: &str) -> Result<bool> {
-    let exists = context
-        .sql
-        .exists("SELECT COUNT(*) FROM leftgrps WHERE grpid=?;", (grpid,))
-        .await?;
-    Ok(exists)
-}
-
 /// Sets group or mailing list chat name.
 pub async fn set_chat_name(context: &Context, chat_id: ChatId, new_name: &str) -> Result<()> {
     rename_ex(context, Sync, chat_id, new_name).await

src/chat/chat_tests.rs

@@ -4867,3 +4867,47 @@ async fn test_long_group_name() -> Result<()> {
 
     Ok(())
 }
+
+/// Regression test for the case
+/// when Bob leaves the group, joins back and deletes the chat.
+/// Previously this resulted in the group
+/// never appearing again without removing Bob
+/// and readding back because the group was
+/// recorded in `leftgrps` for Bob and everyone else
+/// thought that Bob is part of the group.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_leftgrps() -> Result<()> {
+    let mut tcm = TestContextManager::new();
+    let alice = &tcm.alice().await;
+    let bob = &tcm.bob().await;
+
+    // Alice creates a group with Bob and Bob accepts it.
+    let bob_id = alice.add_or_lookup_contact_id(bob).await;
+    let alice_chat_id = create_group(alice, "Group").await?;
+    add_contact_to_chat(alice, alice_chat_id, bob_id).await?;
+    let alice_sent = alice.send_text(alice_chat_id, "Hi!").await;
+    let bob_chat_id = bob.recv_msg(&alice_sent).await.chat_id;
+    bob_chat_id.accept(bob).await?;
+
+    // Bob leaves the group.
+    remove_contact_from_chat(bob, bob_chat_id, ContactId::SELF).await?;
+    let bob_sent = bob.pop_sent_msg().await;
+    alice.recv_msg(&bob_sent).await;
+
+    // Alice adds Bob back, Bob recognizes that the chat is the same.
+    add_contact_to_chat(alice, alice_chat_id, bob_id).await?;
+    let alice_sent = alice.pop_sent_msg().await;
+    let bob_chat_id2 = bob.recv_msg(&alice_sent).await.chat_id;
+    assert_eq!(bob_chat_id, bob_chat_id2);
+
+    // Bob deletes the chat.
+    bob_chat_id.delete(bob).await?;
+    let alice_sent = alice.send_text(alice_chat_id, "Hi again!").await;
+    let bob_chat_id3 = bob.recv_msg(&alice_sent).await.chat_id;
+
+    // Chat ID is new, but not a trash chat.
+    assert_ne!(bob_chat_id3, bob_chat_id);
+    assert!(!bob_chat_id3.is_special());
+
+    Ok(())
+}

src/receive_imf.rs

@@ -2562,26 +2562,12 @@ async fn create_group(
     let mut chat_id = None;
     let mut chat_id_blocked = Default::default();
 
-    async fn self_explicitly_added(
-        context: &Context,
-        mime_parser: &&mut MimeMessage,
-    ) -> Result<bool> {
-        let ret = match mime_parser.get_header(HeaderDef::ChatGroupMemberAdded) {
-            Some(member_addr) => context.is_self_addr(member_addr).await?,
-            None => false,
-        };
-        Ok(ret)
-    }
-
     if chat_id.is_none()
             && !mime_parser.is_mailinglist_message()
             && !grpid.is_empty()
             && mime_parser.get_header(HeaderDef::ChatGroupName).is_some()
             // otherwise, a pending "quit" message may pop up
             && mime_parser.get_header(HeaderDef::ChatGroupMemberRemoved).is_none()
-            // re-create explicitly left groups only if ourself is re-added
-            && (!chat::is_group_explicitly_left(context, grpid).await?
-                || self_explicitly_added(context, &mime_parser).await?)
     {
         // Group does not exist but should be created.
         let grpname = mime_parser