How to save quickfix list per Neovim session using :mksession?

Question

I could not find this in :h sessionoptions.
If this cannot be done, is there another way to save quickfix list to some file and reload it?

Answer 1

Quickfix lists (shortened to "qflist" from here on) are not saved with :mksession. Probably because the list is saved in a temporary file which is scrubbed when exiting the current vim session. But you can save the qflist manually and load it back with :h cgetbuffer.

$ vim
:grep 'pattern'
:copen
:w list.qf
:q
$ vim
:cfile list.qf

But this requires handling another file beside the session file. We can incorporate setting the qflist inside the session file itself, with :h getqflist() and :h setqflist().

Let's incorporate that into a custom MakeSession command.

function! MakeSession(filename, bang) abort
  let filename = a:filename == '' ? 'Session.vim' : a:filename

  " Save window view
  let _w = winsaveview()

  " Get qflist and its title
  let _qflist = getqflist()
  let _qfinfo = getqflist({'title' : 1})
  let _qfopen = !empty(filter(tabpagebuflist(), 'getbufvar(v:val, "&buftype") ==# "quickfix"'))

  " Set all buffers listed in qflist as buflisted
  " Cause an unlisted buffer isn't saved in session file
  " `:h getqflist()` returns file info in the form of `:h bufnr()`
  " If buffer is unlisted and thus not opened with session file
  " then qflist will have nil entries for those files
  for entry in _qflist | call setbufvar(entry['bufnr'], '&buflisted', 1) | endfor

  " Close qflist window
  " because the window is saved in session file as an empty buffer
  " and will open a qflist-window-sized empty buffer
  " in the new vim instance when the session file is sourced
  cclose

  " Save Save the session file
  execute 'mksession' . (a:bang == 1 ? '! ' : ' ') . filename

  " Open the qflist window again
  if _qfopen | cwindow | wincmd p | endif

  " Save the qflist
  let _setqflist = 'call setqflist(' . string(_qflist) . ')'
  let _setqfinfo = 'call setqflist(' . '[],"a",' . string(_qfinfo) . ')'
  call writefile([_setqflist, _setqfinfo], filename, 'a')
  if _qfopen | call writefile(['cwindow', 'wincmd p'], filename, 'a') | endif

  " Restore window view
  call winrestview(_w)
endfunction

command! -nargs=? -bang MakeSession call MakeSession(<q-args>, <bang>0)

---

REMARKS: The function above has the following limitations.

• I have fixed all the limitations I could find. See the edit history of this answer; you'll see. But if some new issue rears up, alert me or edit this answer by either fixing it or adding a remark.

Answer 2

I've converted the vimscript to lua and have ONLY saved the qflist to a file, save session logic will work if you uncomment it. Also created a load Load_qf_list global lua function as well.

function Save_qf_list(filename, bang)
  filename = filename == "" and "qflist.vim" or filename

  -- Save window view
  local _w = vim.fn.winsaveview()

  -- Get qflist and its title
  local _qflist = vim.fn.getqflist()
  local _qfinfo = vim.fn.getqflist { title = 1 }
  local _qfopen = not vim.tbl_isempty(vim.tbl_filter(function(v)
    return vim.fn.getbufvar(v, "&buftype") == "quickfix"
  end, vim.fn.tabpagebuflist()))

  -- Set all buffers listed in qflist as buflisted
  for _, entry in ipairs(_qflist) do
    vim.fn.setbufvar(entry.bufnr, "&buflisted", 1)
  end

  -- Close qflist window
  vim.cmd "cclose"

  -- Save a session file if needed
  -- vim.cmd(string.format('mksession %s %s', bang == 1 and '!' or '', filename))

  -- Open the qflist window again
  if _qfopen then
    vim.cmd "cwindow"
    vim.cmd "wincmd p"
  end

  -- Save the qflist
  local _setqflist = string.format("call setqflist(%s)", vim.fn.string(_qflist))
  local _setqfinfo = string.format('call setqflist([], "a", %s)', vim.fn.string(_qfinfo))
  vim.fn.writefile({ _setqflist, _setqfinfo }, filename, "a")
  if _qfopen then
    vim.fn.writefile({ "cwindow", "wincmd p" }, filename, "a")
  end

  -- Restore window view
  vim.fn.winrestview(_w)
end

vim.cmd "command! -nargs=? -bang SaveQfList lua Save_qf_list(<q-args>, <bang>0)"

function Load_qf_list(filename)
  filename = filename == '' and 'qflist.vim' or filename
  vim.cmd(string.format('source %s', filename))
end

vim.cmd("command! -nargs=? LoadQfList lua Load_qf_list(<q-args>)")

I may modify this behaviour to save the file to the neovim ~/.local/share/nvim directory or allow a path to be given by default or passed as an arg.