供養; もっとよさげなやつ -> https://qiita.com/orokasan/items/81031d08844a04cff81d

nvim-lsp-diagnostics-quickfix.vim

lua << EOF
local function sort_by_key(fn)
  return function(a,b)
    local ka, kb = fn(a), fn(b)
    assert(#ka == #kb)
    for i = 1, #ka do
      if ka[i] ~= kb[i] then
        return ka[i] < kb[i]
      end
    end
    -- every value must have been equal here, which means it's not less than.
    return false
  end
end
local pos_sort = sort_by_key(function(v)
  return {v.start.line, v.start.character}
end)
function l2i(locations)
  local items = {}
  local grouped = setmetatable({}, {
    __index = function(t, k)
      local v = {}
      rawset(t, k, v)
      return v
    end;
  })
  for _, d in ipairs(locations) do
    local start = d.range.start
    local fname = assert(vim.uri_to_fname(d.uri))
    table.insert(grouped[fname], {
      start = start,
      message = d.message;
    })
  end
  local keys = vim.tbl_keys(grouped)
  table.sort(keys)
  for _, fname in ipairs(keys) do
    local rows = grouped[fname]
    table.sort(rows, pos_sort)
    local i = 0
    for line in io.lines(fname) do
      for _, pos in ipairs(rows) do
        local row = pos["start"].line
        if i == row then
          local col
          if pos["start"].character > #line then
            col = #line
          else
            col = vim.str_byteindex(line, pos["start"].character)
          end
          table.insert(items, {
            filename = fname,
            lnum = row + 1,
            col = col + 1;
            text = pos["message"];
          })
        end
      end
      i = i + 1
    end
  end
  return items
end
do
  local method = 'textDocument/publishDiagnostics'
  local default_callback = vim.lsp.callbacks[method]
  vim.lsp.callbacks[method] = function(err, method, result, client_id)
    default_callback(err, method, result, client_id)
    if result and result.diagnostics then
      for _, v in ipairs(result.diagnostics) do
        v.uri = v.uri or result.uri
      end
      vim.fn.setqflist({}, ' ', {
        title = 'Language Server';
        items = l2i(result.diagnostics);
      })
    end
  end
end
EOF