From 31be82e66d412000f1d964a36bb8a03d40eaaeac Mon Sep 17 00:00:00 2001
From: Sean Dewar <6256228+seandewar@users.noreply.github.com>
Date: Thu, 15 May 2025 19:59:37 +0200
Subject: [PATCH] patch 9.1.1393: missing test for switching buffers and
 reusing curbuf

Problem:  The check in buf_freeall that restores curwin subtly prevents
          leaving an unloaded buffer in a window when reusing curbuf, if
          autocommands switch to a different buffer.
Solution: Add a test case that covers this. Also ensure splitting isn't
          possible, as that could do the same (Sean Dewar)

closes: #17325

Signed-off-by: Sean Dewar <6256228+seandewar@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
---
 src/buffer.c                 |  2 +-
 src/testdir/test_autocmd.vim | 27 +++++++++++++++++++++++++++
 src/version.c                |  2 ++
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/src/buffer.c b/src/buffer.c
index 49ec77c7b1..48e8cb63bc 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -909,7 +909,7 @@ buf_freeall(buf_T *buf, int flags)
     // If the buffer was in curwin and the window has changed, go back to that
     // window, if it still exists.  This avoids that ":edit x" triggering a
     // "tabnext" BufUnload autocmd leaves a window behind without a buffer.
-    if (is_curwin && curwin != the_curwin &&  win_valid_any_tab(the_curwin))
+    if (is_curwin && curwin != the_curwin && win_valid_any_tab(the_curwin))
     {
 	block_autocmds();
 	goto_tabpage_win(the_curtab, the_curwin);
diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
index 26f7145652..1988807f75 100644
--- a/src/testdir/test_autocmd.vim
+++ b/src/testdir/test_autocmd.vim
@@ -5415,4 +5415,31 @@ func Test_reuse_curbuf_leak()
   %bw!
 endfunc
 
+func Test_reuse_curbuf_switch()
+  edit asdf
+  let s:asdf_win = win_getid()
+  new
+  let other_buf = bufnr()
+  let other_win = win_getid()
+  augroup testing
+    autocmd!
+    autocmd BufUnload * ++once let s:triggered = 1
+          \| call assert_fails('split', 'E1159:')
+          \| call win_gotoid(s:asdf_win)
+  augroup END
+
+  " Check BufUnload changing curbuf does not cause buflist_new to create a new
+  " buffer while leaving "other_buf" unloaded in a window.
+  enew
+  call assert_equal(1, s:triggered)
+  call assert_equal(other_buf, bufnr())
+  call assert_equal(other_win, win_getid())
+  call assert_equal(1, win_findbuf(other_buf)->len())
+  call assert_equal(1, bufloaded(other_buf))
+
+  unlet! s:asdf_win s:triggered
+  call CleanUpTestAuGroup()
+  %bw!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/version.c b/src/version.c
index e4651653ba..ffcfccb2dc 100644
--- a/src/version.c
+++ b/src/version.c
@@ -709,6 +709,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1393,
 /**/
     1392,
 /**/
-- 
2.47.2