patch 9.1.2055: Division by zero in :file after failing to wipe buffer

Problem:  Division by zero in :file after failing to wipe buffer
          (after 8.2.4631).
Solution: Still call buf_clear_file() when failing to wipe buffer
          (zeertzjq).

closes: #19088

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/buffer.c

@@ -707,7 +707,7 @@ aucmd_abort:
     // 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);
@@ -782,16 +782,13 @@ aucmd_abort:
 
     /*
      * Remove the buffer from the list.
+     * Do not wipe out the buffer if it is used in a window.
      */
-    if (wipe_buf)
+    if (wipe_buf && buf->b_nwindows <= 0)
     {
 	tabpage_T	*tp;
 	win_T		*wp;
 
-	// Do not wipe out the buffer if it is used in a window.
-	if (buf->b_nwindows > 0)
-	    return FALSE;
-
 	FOR_ALL_TAB_WINDOWS(tp, wp)
 	    mark_forget_file(wp, buf->b_fnum);
 

src/testdir/test_autocmd.vim

@@ -3696,7 +3696,7 @@ func Test_BufReadPre_changebuf()
   close!
 endfunc
 
-" Test for BufWipeouti autocmd changing the current buffer when reading a file
+" Test for BufWipeout autocmd changing the current buffer when reading a file
 " in an empty buffer with 'f' flag in 'cpo'
 func Test_BufDelete_changebuf()
   new
@@ -4016,6 +4016,29 @@ func Test_bufwipeout_changes_window()
   %bwipe!
 endfunc
 
+func Test_autocmd_prevent_buf_wipe()
+  " Xa must be the first buffer so that win_close_othertab() puts it in
+  " another window, which causes wiping the buffer to fail.
+  %bwipe!
+
+  file Xa
+  call setline(1, 'foo')
+  setlocal bufhidden=wipe
+  tabnew Xb
+  setlocal bufhidden=wipe
+  autocmd BufUnload Xa ++once ++nested tabonly
+  autocmd BufWinLeave Xb ++once tabnext
+  tabfirst
+
+  edit! Xc
+  call assert_equal('Xc', bufname('%'))
+  tabnext
+  call assert_equal('Xa', bufname('%'))
+  call assert_equal("\n\"Xa\" --No lines in buffer--", execute('file'))
+
+  %bwipe!
+endfunc
+
 func Test_v_event_readonly()
   autocmd CompleteChanged * let v:event.width = 0
   call assert_fails("normal! i\<C-X>\<C-V>", 'E46:')

src/version.c

@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2055,
 /**/
     2054,
 /**/