example.rb

class SomeModel < ActiveRecord::Base
  scope :my_scope, lambda do |param|
    where(blah: param)
  end
end

example.sh

#!/bin/sh

bundle exec ruby -v

bundle list

bundle exec rubocop --rails --only Rails/ScopeArgs app/models/example.rb

Gemfile

source 'https://rubygems.org'

ruby '2.3.0'

gem 'rubocop', '0.38.0'

Gemfile.lock

GEM
  remote: https://rubygems.org/
  specs:
    ast (2.2.0)
    parser (2.3.0.6)
      ast (~> 2.2)
    powerpack (0.1.1)
    rainbow (2.1.0)
    rubocop (0.38.0)
      parser (>= 2.3.0.6, < 3.0)
      powerpack (~> 0.1)
      rainbow (>= 1.99.1, < 3.0)
      ruby-progressbar (~> 1.7)
      unicode-display_width (~> 1.0, >= 1.0.1)
    ruby-progressbar (1.7.5)
    unicode-display_width (1.0.2)

PLATFORMS
  ruby

DEPENDENCIES
  rubocop (= 0.38.0)

BUNDLED WITH
   1.11.2

output.txt

ruby 2.3.0p0 (2015-12-25 revision 53290) [x86_64-darwin15]
Gems included by the bundle:
  * ast (2.2.0)
  * bundler (1.11.2)
  * parser (2.3.0.6)
  * powerpack (0.1.1)
  * rainbow (2.1.0)
  * rubocop (0.38.0)
  * ruby-progressbar (1.7.5)
  * unicode-display_width (1.0.2)
Inspecting 1 file
C

Offenses:

app/models/example.rb:2:20: C: Use lambda/proc instead of a plain method call.
  scope :my_scope, lambda do |param|
                   ^^^^^^

1 file inspected, 1 offense detected