This commit is not precisely atomic, but the changes have evolved, summary:

* The ENV-based interface has been moved upwards, the generator has now a conventional
  initializer.

* RAILS_VERSION is now assumed to be a Git tag. A blank RAILS_VERSION means edge guides.

* In consequence, the EDGE env variable is gone.

* The "local" version is also gone, the current SHA1 is computed for edge guides.

* Assumes guides are generated from a repo checkout (time ago users could
  generate them from gems.)

* The WARNINGS flag is gone in consequence, you cannot disable warnings.

* The `api_link` Markdown helper is fixed.

* Docs about usage have one single place: rake guides:help.

* Links in guides have been revised.

This was never really intended to work (at least not without calling
`define_attribute_methods`, which is less common with Active Record). As
we move forward the intention is to require the use of `attribute` over
`attr_accessor` for more complex model behavior both on Active Record
and Active Model, so this behavior is deprecated.

Fixes #27956.
Close #27963.

[Alex Serban & Sean Griffin]

Switch extension 👉 format as it's more apt here.

Get TODO done in `render_test`

Currently schema dumper lost the unsigned option when primary key is
defined as bigint with unsigned. This commit fixes the issue.

Closes #27960

which is bundled in new apps by default

Delegate `to_sentence` and `to_fomatted_s` to `records`

Use released resque

Fix `test_composite_primary_key_out_of_order`

This reverts commit d6529af2.

`test_composite_primary_key_out_of_order` should use `barcodes_reverse`
table.

Update configuration guide about ActiveRecord's  use_schema_cache_dump option [ci skip]

Add note about breakage in file uploads in controller tests to upgrading guide

primary_keys(table) needs to query various metadata tables in Postgres to
determine the primary key for the table. Previously, it did so using a
complex common table expression against pg_constraint and pg_attribute.

This patch simplifies the query by joining pg_index against pg_attribute
instead of going through pg_constraint. This avoids an expensive unnest,
window function query, and common table expression.

EXPLAINing these queries in Postgres against a database with a single
table with a composite primary key shows a 66% reduction in the plan and
execute latencies. This is significant during application startup time,
especially against very large schemas, where these queries would be even
slower and more numerous.

Closes #27949

guide

ref #26404

[ci skip]

Fix wording

Column options are passed as an hash args then used as `options` hash in
`add_column_options!`. Converting args to attributes is inconvinient for
using options as an hash.

Allow ActiveRecord::Base.as_json to accept a frozen Hash

Fix inspection behavior when the :id column is not primary key

deprecate `halt_callback_chains_on_return_false` instead of `halt_and_display_warning_on_return_false`

deprecate `halt_callback_chains_on_return_false` instead of `halt_and_display_warning_on_return_false`

`halt_and_display_warning_on_return_false` is not a public API and
application is using `halt_callback_chains_on_return_false`.

https://github.com/rails/rails/blob/5-0-stable/railties/lib/rails/generators/rails/app/templates/config/initializers/new_framework_defaults.rb.tt#L29
https://github.com/rails/rails/blob/5-0-stable/activesupport/lib/active_support.rb#L86..L88

Therefore, deprecate messages should be issued for
`halt_callback_chains_on_return_false` instead of
`halt_and_display_warning_on_return_false`.

remove link to edgeapi [ci skip]

Improve linking inside guides

To ease reading the "Active Support Core Extensions" guide, let's
automatically link references to Ruby files.

It's also possible to reference other components' files in the even
though it's not used in the guides at the moment.

[Petr Skocik & Robin Dupret]

To make sure that the user won't look at a feature that doesn't
already exist if they are looking at a previous version of the guides,
let's automatically inject the Rails version the guides have been
generated against.

Deprecate locking of dirty records