https://arika.org/2020/03/17/vim-ale-rubocop/

rubocop-daemon-wrapper.rb

#!/usr/bin/env ruby
# rubocop-daemon-wrapper.rb
require 'rubygems'

if $0 == __FILE__
  bin_dir = Gem::Specification.find_by_name('rubocop-daemon')&.bin_dir
  abort 'rubocop-daemon.gem not found' unless bin_dir

  ENV['RUBYOPT'] = "-r #{File.expand_path(__FILE__).sub(/\.rb\z/, '')}"
  exec(File.join(bin_dir, '../bin/rubocop-daemon-wrapper'), *ARGV)
end

def activate_rubocop_gems(lockfile_path)
  in_gem = in_spec = false
  File.foreach(lockfile_path) do |line|
    case line
    when /^Gem/
      in_gem = true
    when /^\S/
      break if in_gem
    when /^  specs:/
      in_spec = in_gem
    when /^  \S/
      break if in_spec
    when /^    (?<name>rubocop\S*) \((?<version>[.\d]+)\)$/
      m = Regexp.last_match
      gem m[:name], "=#{m[:version]}"
    end
  end
end

dir = Dir.pwd
while dir.start_with?(__dir__)
  begin
    activate_rubocop_gems("#{dir}/Gemfile.lock")
    break
  rescue SystemCallError
    dir = File.dirname(dir)
  end
end

rubocop-spring-wrapper.sh

#!/bin/sh
# rubocop-spring-wrapper.sh
exec spring rubocop "$@"

vimrc

function! s:set_ale_ruby_rubocop_executable()
  let l:project = bundler#project()
  if empty(l:project) || !l:project.has('rubocop')
    return
  endif

  let l:project_root = l:project['root']
  let l:project_rubocop_daemon_wrapper = l:project_root.'/../rubocop-daemon-wrapper.rb'
  let l:project_rubocop_spring_wrapper = l:project_root.'/../rubocop-spring-wrapper.sh'
  let l:rubocop_binstub = l:project_root.'/bin/rubocop'
  if executable(l:project_rubocop_daemon_wrapper)
    unlet $RUBOCOP_DAEMON_USE_BUNDLER
    let b:ale_ruby_rubocop_executable = l:project_rubocop_daemon_wrapper
  elseif l:project.has('rubocop-daemon')
    let $RUBOCOP_DAEMON_USE_BUNDLER = '1'
    let b:ale_ruby_rubocop_executable = l:project.paths()['rubocop-daemon'].'/bin/rubocop-daemon-wrapper'
  elseif executable(l:project_rubocop_spring_wrapper)
    let b:ale_ruby_rubocop_executable = l:project_rubocop_spring_wrapper
  elseif l:project.has('spring-commands-rubocop') && executable(l:rubocop_binstub)
    let b:ale_ruby_rubocop_executable = l:rubocop_binstub
  else
    let b:ale_ruby_rubocop_executable = 'bundle'
  endif
endfunction

augroup my_ale_ruby_rubocop_setting
 au!
 au FileType ruby :call s:set_ale_ruby_rubocop_executable()
augroup END