Squash warning: possibly useless use of a constant in void context

in void context

Update the generate command sample codes [skip ci]

Cache full MySQL version in schema cache

Find query_source_location using lazy Enumerator

Bump RuboCop to 0.67.2

Format a comment to not show up as code [ci skip]

Performance cops will be extracted from RuboCop to RuboCop Performance
when next RuboCop 0.68 will be released.
https://github.com/rubocop-hq/rubocop/issues/5977

RuboCop 0.67 is its transition period.

Since rails/rails repository uses Performance cops, This PR added
rubocop-performance gem to Gemfile.

And this PR fixes some offenses using the following auto-correct.

```console
% bundle exec rubocop -a

Offenses:

activerecord/test/cases/connection_adapters/connection_handlers_multi_db_test.rb:212:26:
C: [Corrected] Layout/SpaceAroundOperators: Operator =
> should be surrounded by a single space.
              "primary"  => { adapter: "sqlite3", database: "db/primary.sqlite3" }
                         ^^
activerecord/test/cases/connection_adapters/connection_handlers_multi_db_test.rb:239:26:
C: [Corrected] Layout/SpaceAroundOperators: Operator => should be
surrounded by a single space.
              "primary"  => { adapter: "sqlite3", database: "db/primary.sqlite3" }
                         ^^
actionview/test/template/resolver_shared_tests.rb:1:1: C: [Corrected]
Style/FrozenStringLiteralComment: Missing magic comment #
frozen_string_literal: true.
module ResolverSharedTests
^
actionview/test/template/resolver_shared_tests.rb:10:33: C: [Corrected]
Layout/SpaceAroundEqualsInParameterDefault: Surrounding space missing in
default value assignment.
  def with_file(filename, source="File at #{filename}")
                                ^
actionview/test/template/resolver_shared_tests.rb:106:5: C: [Corrected]
Rails/RefuteMethods: Prefer assert_not_same over refute_same.
    refute_same a, b
    ^^^^^^^^^^^

2760 files inspected, 5 offenses detected, 5 offenses corrected
```

[ci skip]

Migrate Code Climate config file to new configuration

I don't know whether have to move to a new configuration, but I think
there is no need to keep using the old configuration.

Ref: https://docs.codeclimate.com/docs/advanced-configuration#section-analysis-configuration-versions

Since 8180c396, remaining transaction state is cleared in
`force_clear_transaction_record_state` to less work
`sync_with_transaction_state`. But it caused a race condition that
`@transaction_state` would be cleared by other threads if the state is
finalized.

To work as before, snapshot `@transaction_state` to local variable not
to refer `@transaction_state` directly.

Fixes #35983.

This way, we only need to filter the backtrace up to the first non-noise
stack frame.

This also updates noise to be able to deal with being passed a lazy
enum. We don't need this anywhere, but it seemed better for this to be
consistent.

mounted routes with non-word characters

Remove `required: true` from the model generator template

De-duplicate templates, introduce UnboundTemplate

Add section on PostgreSQL to the guides index [ci skip]

Notes tags registration

Ensure a handler is set when using `connected_to`

`belongs_to` association have `required: true` by default
https://github.com/rails/rails/pull/18937 onwards so we don't need it
in the generator template.
We still need the code for required in the command line generator as
it adds `null: false` in the migration.

Remove unused modules from StrongParameters

Unless I'm missing some undocumented use case, these modules aren't
needed in `StrongParameters` anymore since 8e221127. Also, all
actionpack tests are passing without them.

Before this fix, `touch` only clears dirty tracking for touched
attributes, doesn't track saved (touched) changes.

This fixes that tracks saved changes and carry over remaining changes.

Fixes #33429.
Closes #34306.

This is the follow up of 10fa3b37.

In `app:update`, it is decided whether to skip depending on whether
`Spring` is defined or not.
However, `spring` is not currently specified in Gemfile. As a result,
`app:update` determines that `Spring` is not used, and diff appears in
the result file.
If there is a difference, the console for processing the difference is
output and the test stops. To avoid this, do not include `Spring` in app.

This is a bit strange approach, so I will revisit this later.

Do not execute `rails app:update` in railties/test/generators/app_generator_test.rb

make change_column_comment and change_table_comment invertible

We can revert migrations using `change_column_comment` or
`change_table_comment` at current master.
However, results are not what we expect: comments are remained in new
status.
This change tells previous comment to these methods in a way like
`change_column_default`.

The mock is called three times because the `spring_install?` call has
been added in 65344f25.

All transaction states (:committed, :fully_committed, :rolledback,
:fully_rolledback) are mutually exclusive.
And also, `force_clear_transaction_record_state` should clear
`@transaction_state` as well.

Make `Redis.cache.fetch_multi([])` not throw an error

It's unusable and not ready to ship in Rails 6.0. We'll rewrite it for 6.1.

Ensure acceptance validator is not applied more than once to Person

Use individual execution counters when calculating retry delay