From 85bf170ff0d54471fe88903009a3fec4ef3e6e8c Mon Sep 17 00:00:00 2001
From: silverwind <me@silverwind.io>
Date: Fri, 1 Mar 2024 17:12:21 +0100
Subject: [PATCH] Fix incorrect diff expander for deletion of last lines in a
 file (#29501)

Fixes: https://github.com/go-gitea/gitea/issues/29498

I don't quite understand this code, but this change does seem to fix the
issue and I tested a number of diffs with it and saw no issue. The
function gets such value if last line is an addition:

```
  LastLeftIdx: (int) 0,
  LastRightIdx: (int) 47,
  LeftIdx: (int) 47,
  RightIdx: (int) 48,
```

If it's a deletion, it gets:

```
  LastLeftIdx: (int) 47,
  LastRightIdx: (int) 0,
  LeftIdx: (int) 48,
  RightIdx: (int) 47,
```

So I think it's correct to make this check respect both left and right
side.

(cherry picked from commit 3b99066aa866e51e6a610716eaddfd1ea3645a67)
---
 services/gitdiff/gitdiff.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/services/gitdiff/gitdiff.go b/services/gitdiff/gitdiff.go
index 715c5bf9b8..2b796181d8 100644
--- a/services/gitdiff/gitdiff.go
+++ b/services/gitdiff/gitdiff.go
@@ -152,7 +152,7 @@ func (d *DiffLine) GetBlobExcerptQuery() string {
 
 // GetExpandDirection gets DiffLineExpandDirection
 func (d *DiffLine) GetExpandDirection() DiffLineExpandDirection {
-	if d.Type != DiffLineSection || d.SectionInfo == nil || d.SectionInfo.RightIdx-d.SectionInfo.LastRightIdx <= 1 {
+	if d.Type != DiffLineSection || d.SectionInfo == nil || d.SectionInfo.LeftIdx-d.SectionInfo.LastLeftIdx <= 1 || d.SectionInfo.RightIdx-d.SectionInfo.LastRightIdx <= 1 {
 		return DiffLineExpandNone
 	}
 	if d.SectionInfo.LastLeftIdx <= 0 && d.SectionInfo.LastRightIdx <= 0 {