patch 9.0.0789: dummy buffer ends up in a window
Problem: Dummy buffer ends up in a window.
Solution: Disallow navigating to a dummy buffer.
diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
index 0706e73..6ba1b02 100644
--- a/src/testdir/test_autocmd.vim
+++ b/src/testdir/test_autocmd.vim
@@ -3857,4 +3857,24 @@
call assert_true(autocmd_delete([test_null_dict()]))
endfunc
+func Test_autocmd_split_dummy()
+ " Autocommand trying to split a window containing a dummy buffer.
+ auto BufReadPre * exe "sbuf " .. expand("<abuf>")
+ " Avoid the "W11" prompt
+ au FileChangedShell * let v:fcs_choice = 'reload'
+ func Xautocmd_changelist()
+ cal writefile(['Xtestfile2:4:4'], 'Xerr')
+ edit Xerr
+ lex 'Xtestfile2:4:4'
+ endfunc
+ call Xautocmd_changelist()
+ call assert_fails('call Xautocmd_changelist()', 'E86:')
+
+ au! BufReadPre
+ au! FileChangedShell
+ delfunc Xautocmd_changelist
+ bwipe! Xerr
+ call delete('Xerr')
+endfunc
+
" vim: shiftwidth=2 sts=2 expandtab