From ab236a6008a388e16a6c360ea76e16cfcae82d71 Mon Sep 17 00:00:00 2001
From: Antonio Scandurra <me@as-cii.com>
Date: Wed, 17 Aug 2022 11:26:05 +0200
Subject: [PATCH] Fix divergence bug in undo/redo

As part of #1405, we changed the way we performed undo and redo to
support combining transactions that were not temporally adjacent for
IME purposes.

We introduced a bug with that release that caused divergence
when performing undo: the bug was caused by only changing the visibility
of fragments whose insertion id was contained in the undo operation. However,
an undo operation also affects deletions which we were mistakenly not
considering. Randomized tests caught this but I guess we didn't run enough
of them.
---
 crates/language/src/proto.rs |  2 --
 crates/rpc/proto/zed.proto   |  3 +--
 crates/text/src/text.rs      | 12 ++----------
 3 files changed, 3 insertions(+), 14 deletions(-)

diff --git a/crates/language/src/proto.rs b/crates/language/src/proto.rs
index 047cef3ab6..df1e0e0959 100644
--- a/crates/language/src/proto.rs
+++ b/crates/language/src/proto.rs
@@ -39,7 +39,6 @@ pub fn serialize_operation(operation: &Operation) -> proto::Operation {
                 local_timestamp: undo.id.value,
                 lamport_timestamp: lamport_timestamp.value,
                 version: serialize_version(&undo.version),
-                transaction_version: serialize_version(&undo.transaction_version),
                 counts: undo
                     .counts
                     .iter()
@@ -199,7 +198,6 @@ pub fn deserialize_operation(message: proto::Operation) -> Result<Operation> {
                             )
                         })
                         .collect(),
-                    transaction_version: deserialize_version(undo.transaction_version),
                 },
             }),
             proto::operation::Variant::UpdateSelections(message) => {
diff --git a/crates/rpc/proto/zed.proto b/crates/rpc/proto/zed.proto
index f52815a8be..3da7f62ac7 100644
--- a/crates/rpc/proto/zed.proto
+++ b/crates/rpc/proto/zed.proto
@@ -901,8 +901,7 @@ message Operation {
         uint32 local_timestamp = 2;
         uint32 lamport_timestamp = 3;
         repeated VectorClockEntry version = 4;
-        repeated VectorClockEntry transaction_version = 6;
-        repeated UndoCount counts = 7;
+        repeated UndoCount counts = 5;
     }
 
     message UpdateSelections {
diff --git a/crates/text/src/text.rs b/crates/text/src/text.rs
index ff78f4a14b..1f2e4e7c7a 100644
--- a/crates/text/src/text.rs
+++ b/crates/text/src/text.rs
@@ -512,7 +512,6 @@ pub struct EditOperation {
 pub struct UndoOperation {
     pub id: clock::Local,
     pub counts: HashMap<clock::Local, u32>,
-    pub transaction_version: clock::Global,
     pub version: clock::Global,
 }
 
@@ -1109,14 +1108,8 @@ impl Buffer {
                 let mut fragment = fragment.clone();
                 let fragment_was_visible = fragment.visible;
 
-                if fragment.was_visible(&undo.transaction_version, &self.undo_map)
-                    || undo
-                        .counts
-                        .contains_key(&fragment.insertion_timestamp.local())
-                {
-                    fragment.visible = fragment.is_visible(&self.undo_map);
-                    fragment.max_undos.observe(undo.id);
-                }
+                fragment.visible = fragment.is_visible(&self.undo_map);
+                fragment.max_undos.observe(undo.id);
 
                 let old_start = old_fragments.start().1;
                 let new_start = new_fragments.summary().text.visible;
@@ -1297,7 +1290,6 @@ impl Buffer {
             id: self.local_clock.tick(),
             version: self.version(),
             counts,
-            transaction_version: transaction.start,
         };
         self.apply_undo(&undo)?;
         let operation = Operation::Undo {