patch 8.2.1059: crash when using :tabonly in an autocommand

Problem:    Crash when using :tabonly in an autocommand. (Yegappan Lakshmanan)
Solution:   Do not allow the autocommand window to be closed.

src/ex_docmd.c

@@ -5178,6 +5178,13 @@ ex_win_close(
     int		need_hide;
     buf_T	*buf = win->w_buffer;
 
+    // Never close the autocommand window.
+    if (win == aucmd_win)
+    {
+	emsg(_(e_autocmd_close));
+	return;
+    }
+
     need_hide = (bufIsChanged(buf) && buf->b_nwindows <= 1);
     if (need_hide && !buf_hide(buf) && !forceit)
     {

src/globals.h

@@ -1765,6 +1765,7 @@ EXTERN char e_float_as_string[] INIT(= N_("E806: using Float as a String"));
 #endif
 EXTERN char e_dirnotf[]	INIT(= N_("E919: Directory not found in '%s': \"%s\""));
 EXTERN char e_au_recursive[]	INIT(= N_("E952: Autocommand caused recursive behavior"));
+EXTERN char e_autocmd_close[]	INIT(= N_("E813: Cannot close autocmd or popup window"));
 #ifdef FEAT_MENU
 EXTERN char e_menuothermode[]	INIT(= N_("E328: Menu only exists in another mode"));
 #endif

src/testdir/test_autocmd.vim

@@ -2617,7 +2617,27 @@ func Test_close_autocmd_window()
     au!
   augroup END
   augroup! aucmd_win_test2
-  %bw!
+  %bwipe!
+endfunc
+
+" Test for trying to close the tab that has the temporary window for exeucing
+" an autocmd.
+func Test_close_autocmd_tab()
+  edit one.txt
+  tabnew two.txt
+   augroup aucmd_win_test
+    au!
+    au BufEnter * if expand('<afile>') == 'one.txt' | tabfirst | tabonly | endif
+  augroup END
+
+  call assert_fails('doautoall BufEnter', 'E813:')
+
+  tabonly
+  augroup aucmd_win_test
+    au!
+  augroup END
+  augroup! aucmd_win_test
+  %bwipe!
 endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1059,
 /**/
     1058,
 /**/

src/window.c

@@ -2461,7 +2461,7 @@ win_close(win_T *win, int free_buf)
 	return FAIL; // window is already being closed
     if (win_unlisted(win))
     {
-	emsg(_("E813: Cannot close autocmd or popup window"));
+	emsg(_(e_autocmd_close));
 	return FAIL;
     }
     if ((firstwin == aucmd_win || lastwin == aucmd_win) && one_window())