Fix dirty check for Float::NAN

[xronos-i-am]

Summary

The problem: Float::NAN is special value in ruby. It can't be compared with ==. Because of this dirty check failed

require "bundler/inline"

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

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  gem "rails", "~> 6.1"
  gem "sqlite3"
end

require "active_record"
require "minitest/autorun"

ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")

ActiveRecord::Schema.define do
  create_table :warehouse_receipts, force: true do |t|
    t.decimal :vat_coef
  end
end

class WarehouseReceipt < ActiveRecord::Base
end

class Test < Minitest::Test
  def test_nan_dirty
    wr = WarehouseReceipt.create!(vat_coef: Float::NAN)
    wr.vat_coef = Float::NAN
    assert !wr.changed? # Expected false to be truthy.
  end
end

[rails-bot]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.
Thank you for your contributions.

[zzak]

🤔 I thought I've seen a similar issue/PR recently but now I can't find it.

@xronos-i-am Is this still something you're interested in?

[xronos-i-am]

@xronos-i-am Is this still something you're interested in?

no

[zzak]

@xronos-i-am I realize you may not feel like finishing this PR, but I'd like to leave it open to see if anyone else may be interested in this. At worst, @rails-bot auto-closes this PR if there is no activity after some time.

I also was wondering since I just realize this change was targeting 6-1-stable is this commit already fixed in main and you're requesting a backport? Do you have any other context on this change? 🙇

[xronos-i-am]

I also was wondering since I just realize this change was targeting 6-1-stable is this commit already fixed in main and you're requesting a backport? Do you have any other context on this change?

There were too many issues with Float::NAN therefore I solve my problem in another way

[marcelolx]

@zzak I ran the script against main and it seems that the problem still exists. I'll pick up this

require "bundler/inline"

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

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  gem "rails", github: "rails/rails", branch: "main"
  gem "sqlite3"
end

require "active_record"
require "minitest/autorun"

ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")

ActiveRecord::Schema.define do
  create_table :warehouse_receipts, force: true do |t|
    t.decimal :vat_coef
  end
end

class WarehouseReceipt < ActiveRecord::Base
end

class Test < Minitest::Test
  def test_nan_dirty
    wr = WarehouseReceipt.create!(vat_coef: Float::NAN)
    wr.vat_coef = Float::NAN
    assert !wr.changed? # Expected false to be truthy.
  end
end

[marcelolx]

@zzak I opened a PR with a test case

[byroot]

Closing in favor of #42831