For multiple databases we attempt to generate the tasks by reading the
database.yml before the Rails application is booted. This means that we
need to strip out ERB since it could be reading Rails configs.

In some cases like https://github.com/rails/rails/issues/36540 the ERB
is too complex and we can't overwrite with the DummyCompilier we used in
https://github.com/rails/rails/pull/35497. For the complex causes we
simply issue a warning that says we couldn't infer the database tasks
from the database.yml.

While working on this I decided to update the code to only load the
database.yml once initially so that we avoid having to issue the same
warning multiple times. Note that this had no performance impact in my
testing and is merely for not having to save the error off somewhere.
Also this feels cleaner.

Note that this will not break running tasks that exist, it will just
mean that tasks for multi-db like `db:create:other_db` will not be
generated. If the database.yml is actually unreadable it will blow up
during normal rake task calls.

Fixes #36540

Merge pull request #36210 from vishaltelangre/raise-record-invalid-when-associations-fail-to-save-due-to-uniqueness-failure

Fix: ActiveRecord::RecordInvalid is not raised when an associated record fails to #save! due to uniqueness validation failure

Also deduplicate schema cache data when using the init_with interface

Make `ActionDispatch::Response#content_type` behavior configurable

I changed return value of `ActionDispatch::Response#content_type` in #36034.
But this change seems to an obstacle to upgrading. https://github.com/rails/rails/pull/36034#issuecomment-498795893

Therefore, I restored the behavior of `ActionDispatch::Response#content_type`
to 5.2 and deprecated old behavior. Also, made it possible to control the
behavior with the config.

Address test_statement_cache_with_in_clause failure

Revert schema dumper to use strings rather than integers

This failure is occasional, does not always reproduce.

```ruby
$ cd activerecord
$ bundle exec rake test_postgresql
... snip ...

....F

Failure:
ActiveRecord::BindParameterTest#test_statement_cache_with_in_clause [/home/yahonda/git/rails/activerecord/test/cases/bind_parameter_test.rb:97]:
Expected: [1, 3]
  Actual: [3, 1]

rails test home/yahonda/git/rails/activerecord/test/cases/bind_parameter_test.rb:93

```

I think we should change this, but not in 6-0-stable since that's
already in RC and I was trying to only make changes that won't require
any app changes.

This reverts a portion of https://github.com/rails/rails/pull/36439 that
made all schema migration version numbers get dumped as an integer.
While it doesn't _really_ matter it did change behavior. We should bring
this back in 6.1 with a deprecation.

Add test cases to ensure deterministic order for ordinal methods

Include BCC in the mail that sent from the development page

The BCC should be included as we show input field for BCC in view.
https://github.com/rails/rails/blob/bf625f7fecabbcda22b388e088ad5c29016b2385/actionmailbox/app/views/rails/conductor/action_mailbox/inbound_emails/new.html.erb#L21-L24

Allow using env var to specify pidfile

Stop serializing and parsing columns_hash in Active Record schema caches

Autoload SyntaxErrorInTemplate

When a SyntaxError is detected in a template we raise this exception. On
a first request to the server the exception we get a NameError since the
exception is not required from `active_view/template/error.rb` yet.
However later on it gets required and a second request will succeed.
On the first request we see the rails "Something Wen Wrong" page and not
the expected syntax error in template error page with the webconsole and
stacktrace. By autoloading the constant we fix this issue.
Co-authored-by: NGannon McGibbon <gannon.mcgibbon@gmail.com>

Better error message for calling columns_hash

When a record does not have a table name, as in the case for a record
with `self.abstract_class = true` and no `self.table_name` set the error
message raises a cryptic:
"ActiveRecord::StatementInvalid: Could not find table ''" this patch now
raises a new `TableNotSpecified Error`

Fixes: #36274
Co-Authored-By: NEugene Kenny <elkenny@gmail.com>

Before 1340498d, `order` with no-op value (e.g. `nil`, `""`) had broken
the contract of ordinal methods, which returns a result deterministic
ordered.

Previously it was only possible to specify the location of the pidfile
for the 'rails server' command with the '-P' flag. This adds support for
specifying the pidfile using a PIDFILE env var, which can still be
overridden by the '-P' flag and with the default pidfile path unchanged.

The motivation for this feature comes from using Docker to run multiple
instances of the same rails app. When developing a rails app with
Docker, it's common to bind-mount the rails root directory in the
running container, so that changes to files are shared between the
container and the host. However, this doesn't work so well with the
pidfile and it's necessary to (remember to) add a '-P' flag to the
'rails server' command line; being able to specify this flag using an
env var would make developing with Rails+Docker a bit simpler.

Deduplicate various Active Record schema cache structures

Avoid redundant `time.getutc` call if it is already utc time object

Fix TranslationHelper#translate handling of Hash defaults

Currently `type.serialize` and `connection.{quote|type_cast}` for a time
object always does `time.getutc` call regardless of whether it is
already utc time object or not, that duplicated proccess
(`connection.type_cast(type.serialize(time))`) allocates extra/useless
time objects for each type casting.

This avoids that redundant `time.getutc` call if it is already utc time
object. In the case of a model has timestamps (`created_at` and
`updated_at`), it avoids 6,000 time objects allocation for 1,000 times
`model.save`.

```ruby
ObjectSpace::AllocationTracer.setup(%i{path line type})

pp ObjectSpace::AllocationTracer.trace {
  1_000.times { User.create }
}.select { |k, _| k[0].end_with?("quoting.rb", "time_value.rb") }
```

Before (c104bfe4):

```
{["~/rails/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb",
  203,
  :T_ARRAY]=>[1004, 0, 778, 0, 1, 0],
 ["~/rails/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb",
  220,
  :T_STRING]=>[2, 0, 2, 1, 1, 0],
 ["~/rails/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb",
  209,
  :T_ARRAY]=>[8, 0, 8, 1, 1, 0],
 ["~/rails/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb",
  57,
  :T_ARRAY]=>[4, 0, 4, 1, 1, 0],
 ["~/rails/activemodel/lib/active_model/type/helpers/time_value.rb",
  17,
  :T_DATA]=>[4000, 0, 3096, 0, 1, 0],
 ["~/rails/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb",
  120,
  :T_DATA]=>[2000, 0, 1548, 0, 1, 0],
 ["~/rails/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb",
  126,
  :T_STRING]=>[4000, 0, 3096, 0, 1, 0]}
```

After (this change):

```
{["~/rails/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb",
  203,
  :T_ARRAY]=>[1004, 0, 823, 0, 1, 0],
 ["~/rails/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb",
  220,
  :T_STRING]=>[2, 0, 2, 1, 1, 0],
 ["~/rails/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb",
  209,
  :T_ARRAY]=>[8, 0, 8, 1, 1, 0],
 ["~/rails/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb",
  57,
  :T_ARRAY]=>[4, 0, 4, 1, 1, 0],
 ["~/rails/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb",
  126,
  :T_STRING]=>[2000, 0, 1638, 0, 1, 0]}
```

PostgreSQL: Fix GROUP BY with ORDER BY virtual count attribute

GROUP BY with virtual count attribute is invalid for almost all
databases, but it is valid for PostgreSQL, and it had worked until Rails
5.2.2, so it is a regression for Rails 5.2.3 (caused by 311f0011).

I can't find perfectly solution for fixing this for now, but I would not
like to break existing apps, so I decided to allow referencing virtual
count attribute in ORDER BY clause when GROUP BY aggrigation (it partly
revert the effect of 311f0011) to fix the regression #36022.

Fixes #36022.

Fix typo initialzer -> initializer

[ci skip]

Delete method definition in rails that is compatible with ruby defini…

Tests are also only on the `Time` class

Update doc forgetting to erase when moved

Update guide `Date` class to `Time` class and defined file

Update guide correction omission

Ref: bcf370d6, 06ab7b27.

Remove unused `Arel::Attributes.for`

Delete 'ruby' in the description of the method defined in rails [skip ci]