From 13f3bef685bfa209f6ff0ad1915a9a5aa63588e2 Mon Sep 17 00:00:00 2001
From: zeertzjq <zeertzjq@outlook.com>
Date: Wed, 18 Oct 2023 09:26:09 +0800
Subject: [PATCH] fix(move): check the correct buffer

(cherry picked from commit 56ffab5522b2b30e86a17e975c2e005f7f603f3d)
---
 src/nvim/move.c                        |  2 +-
 test/functional/ui/inccommand_spec.lua | 30 ++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/src/nvim/move.c b/src/nvim/move.c
index 5d8136107e..0b81f34805 100644
--- a/src/nvim/move.c
+++ b/src/nvim/move.c
@@ -166,7 +166,7 @@ void update_topline(win_T *wp)
   old_topfill = wp->w_topfill;
 
   // If the buffer is empty, always set topline to 1.
-  if (buf_is_empty(curbuf)) {             // special case - file is empty
+  if (buf_is_empty(wp->w_buffer)) {  // special case - file is empty
     if (wp->w_topline != 1) {
       redraw_later(wp, UPD_NOT_VALID);
     }
diff --git a/test/functional/ui/inccommand_spec.lua b/test/functional/ui/inccommand_spec.lua
index 7f05f0f901..217a713c93 100644
--- a/test/functional/ui/inccommand_spec.lua
+++ b/test/functional/ui/inccommand_spec.lua
@@ -3087,6 +3087,36 @@ it(':substitute with inccommand works properly if undo is not synced #20029', fu
     baz]])
 end)
 
+it(':substitute with inccommand does not unexpectedly change viewport #25697', function()
+  clear()
+  local screen = Screen.new(45, 5)
+  common_setup(screen, 'nosplit', long_multiline_text)
+  command('vnew | tabnew | tabclose')
+  screen:expect([[
+    ^                      │£ m n                 |
+    {15:~                     }│t œ ¥                 |
+    {15:~                     }│                      |
+    {11:[No Name]              }{10:[No Name] [+]         }|
+                                                 |
+  ]])
+  feed(':s/')
+  screen:expect([[
+                          │£ m n                 |
+    {15:~                     }│t œ ¥                 |
+    {15:~                     }│                      |
+    {11:[No Name]              }{10:[No Name] [+]         }|
+    :s/^                                          |
+  ]])
+  feed('<Esc>')
+  screen:expect([[
+    ^                      │£ m n                 |
+    {15:~                     }│t œ ¥                 |
+    {15:~                     }│                      |
+    {11:[No Name]              }{10:[No Name] [+]         }|
+                                                 |
+  ]])
+end)
+
 it('long :%s/ with inccommand does not collapse cmdline', function()
   local screen = Screen.new(10,5)
   clear()