ActiveRecord::Migration[7.0]'s rename_table uses 7.1's new truncated index name format

[r7kamura]

Steps to reproduce

# frozen_string_literal: true

require "bundler/inline"

gemfile do
  source "https://rubygems.org"

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

  gem "rails", "7.1.3"
  # If you want to test against edge Rails replace the previous line with this:
  # gem "rails", github: "rails/rails", branch: "main"

  gem "sqlite3"
end

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

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
end

class Post < ActiveRecord::Base
end

class BugTest < Minitest::Test
  def test_index_name_after_rename_table_with_long_table_name
    long_table_name = "a" * 48

    migration_class = Class.new(ActiveRecord::Migration[7.0]) do
      define_method :migrate do |x|
        create_table :posts do |t|
          t.string :title
          t.index :title
        end
        rename_table :posts, long_table_name
      end
    end
    migration = migration_class.new

    ActiveRecord::Migrator.new(
      :up,
      [migration],
      ActiveRecord::Base.connection.schema_migration,
      ActiveRecord::Base.connection.internal_metadata
    ).migrate

    assert_equal "index_#{long_table_name}_on_title", ActiveRecord::Base.connection.indexes(long_table_name).first.name
  end
end

Expected behavior

The above test should pass.

This means that since the index name was renamed to index_aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa_on_title in Rails 7.0 and earlier, if ActiveRecord::Migration[7.0] or earlier is specified, the same name should be used even in Rails 7.1 or later.

Actual behavior

The above test fails with the following output:

F

Failure:
BugTest#test_index_name_after_rename_table_with_long_table_name [example.rb:53]:
--- expected
+++ actual
@@ -1 +1 @@
-"index_aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa_on_title"
+"idx_on_title_0b3d36c24b"



bin/rails test example.rb:32



Finished in 0.026827s, 37.2753 runs/s, 37.2753 assertions/s.
1 runs, 1 assertions, 1 failures, 0 errors, 0 skips

As a result, if db/migrate contains rename_table, the index names created between Rails 7.0 and 7.1 may be different.

System configuration

Rails version: 7.1.3

Ruby version: ruby 3.2.2 (2023-03-30 revision e51014f9c0) [x86_64-linux]

Other information

This is due to the following change:

• Fix Rails generated index name being too long #47753

I think a similar change to the following is needed for #rename_table:

• Ensure pre-7.1 migrations use legacy index names when using create_table #47863

[fatkodima]

Looking into it. Will open a PR soon.