From d0f7e5f075b85b25b09b76868da4d144385734b5 Mon Sep 17 00:00:00 2001
From: Antonio Scandurra <me@as-cii.com>
Date: Thu, 6 Jan 2022 15:33:02 +0100
Subject: [PATCH] Maintain excerpt ordering correctly when some errors don't
 change

---
 crates/diagnostics/src/diagnostics.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/crates/diagnostics/src/diagnostics.rs b/crates/diagnostics/src/diagnostics.rs
index 28f82d7fe3..5c7f4f01bd 100644
--- a/crates/diagnostics/src/diagnostics.rs
+++ b/crates/diagnostics/src/diagnostics.rs
@@ -219,6 +219,7 @@ impl ProjectDiagnosticsEditor {
             loop {
                 let mut to_insert = None;
                 let mut to_invalidate = None;
+                let mut to_keep = None;
                 match (old_groups.peek(), new_groups.peek()) {
                     (None, None) => break,
                     (None, Some(_)) => to_insert = new_groups.next(),
@@ -229,7 +230,7 @@ impl ProjectDiagnosticsEditor {
                         match compare_diagnostics(old_primary, new_primary, &snapshot) {
                             Ordering::Less => to_invalidate = old_groups.next(),
                             Ordering::Equal => {
-                                old_groups.next();
+                                to_keep = old_groups.next();
                                 new_groups.next();
                             }
                             Ordering::Greater => to_insert = new_groups.next(),
@@ -337,6 +338,8 @@ impl ProjectDiagnosticsEditor {
                     excerpts.remove_excerpts(group_state.excerpts.iter(), excerpts_cx);
                     group_ixs_to_remove.push(group_ix);
                     blocks_to_remove.extend(group_state.blocks.keys().copied());
+                } else if let Some((_, group)) = to_keep {
+                    prev_excerpt_id = group.excerpts.last().unwrap().clone();
                 }
             }