Fix PostgreSQL Cidr#change? to compare with address prefix

[taketo1113]

Motivation / Background

This Pull Request has been created because fixes #51582

Detail

This Pull Request changes to overrideActiveRecord::ConnectionAdapters::PostgreSQL::OID::Cidr#changed?.
It added to compare address prefix of IPAddr class.

Additional information

I’m proposing to fix IPAddr#== comparing address prefix for the cause of this problem.
ruby/ipaddr#69

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Unrelated changes should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
• Tests are added or updated if you fix a bug or add a feature.
• CHANGELOG files are updated for the changed libraries if there is a behavior change or additional feature. Minor bug fixes and documentation changes should not be included.

[yahonda]

Backported to the 7-1-stable branch via 887210f

[vipulnsward]

@yahonda This needs a changelog as its a change in behavior?

[yahonda]

Let me add a change log entry for this change. Thanks for the heads-up.

[yahonda]

Opened #51742 to add a changelog entry for this change.

[chaadow]

@yahonda @taketo1113 I'm on Rails 7-1 stable. and this makes my production app crash under certain circumstances.

when #save is called on an activerecord model. here is the stack trace:

[chaadow]

Honestly I wish I could reproduce the bug (it's in production) but it's so mystical. all I can say is, it's related to this PR and it was done on a "ActiveRecord#save" call. on an unpersisted instance

(probably the reason why old_value.prefix is nil ?)

but what's mystical to me is why it goes through the changed? call here even though I have 0 CIDR columns

[chaadow]

@taketo1113 @yahonda I finally managed to recreate the issue

It's due to the fact that inet inherits from CIDR.

this part helped me get less confused and better investigate and reproduce the issue

# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  # If you want to test against edge Rails replace the previous line with this:
  gem "rails", github: "rails/rails", branch: "main"

  gem "pg"
end

require "active_record"
require "minitest/autorun"
require "logger"

db_config = {
  adapter: 'postgresql',
  database: 'inet_cidr_test',
  host: 'localhost', # Change this to your PostgreSQL host
  port: 5432,
  username: 'postgres', # Change this to your PostgreSQL username
  password: 'postgres'  # Change this to your PostgreSQL password
}

ActiveRecord::Base.establish_connection(db_config.except(:database))
ActiveRecord::Base.connection.drop_database(db_config[:database]) rescue nil
ActiveRecord::Base.connection.create_database(db_config[:database])

ActiveRecord::Base.establish_connection(db_config)
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :users, force: true do |t|
    t.inet :ip_address
  end
end

class User < ActiveRecord::Base
end


class BugTest < Minitest::Test
  def test_ip_address_with_empty_string
    User.create!(ip_address: '')
  end
end

[carlosantoniodasilva]

@chaadow if you haven't already, please open up a separate/new issue to help track this.

[taketo1113]

I confirmed to reproduce issue and created PR (#51758)