When a class has a belongs_to or has_one relationship with dependent: :destroy
option enabled, objects of this class should not be deleted if it's dependents
cannot be deleted.

Example:

    class Parent
      has_one :child, dependent: :destroy
    end

    class Child
      belongs_to :parent, inverse_of: :child
      before_destroy { throw :abort }
    end

    c = Child.create
    p = Parent.create(child: c)

    p.destroy

    p.destroyed? # expected: false; actual: true;

Fixes #32022

This issue is caused by `@_trigger_update_callback` won't be updated due
to `_update_record` in `Locking::Optimistic` doesn't call `super` when
optimistic locking is enabled.

Now optimistic locking concern when updating is supported by
`_update_row` low level API, therefore overriding `_update_record` is no
longer necessary.

Removing the method just fix the issue.

Closes #29096.
Closes #29321.
Closes #30823.

Currently primary key value can not be updated if a record has a locking
column because of `_update_record` in `Locking::Optimistic` doesn't
respect `id_in_database` as primary key value unlike in `Persistence`.

And also, if a record has dirty primary key value, it may destroy any
other record by the lock version of dirty record itself.

When updating/destroying persisted records, it should identify
themselves by `id_in_database`, not by dirty primary key value.

Related to https://github.com/rails/rails/commit/d4eb0dc89ee6b476e2e10869dc282a96f956c6c7#r27830891

This removes `|| id` which were added in #9963 and #23887 since it is no
longer necessary.

This reverts ignoring polymorphic error introduced at 02da8aea.

What the ignoring want to solve was caused by force eager loading
regardless of whether it is necessary, but it has been fixed by #29043.

The ignoring is now only causing a mismatch of `exists?` behavior with
`to_a`, `count`, etc. It should behave consistently.

This is an alternative of #29722, and follow up of #32048.

This does not change the current behavior, but makes it easier to modify
all polymorphic names consistently.

Ruby 2.4+ provides `Hash#compact` and `Hash#compact!` natively,
so `active_support/core_ext/hash/compact` is no longer necessary.

Since Rails 6 requires Ruby 2.4.1+.

https://bugs.ruby-lang.org/issues/12752
https://ruby-doc.org/core-2.4.0/String.html#method-i-unpack1

This comment was added at 070dda28. That arguments has already been
changed since those are internal nodoc classes, but the comment does not
reflect the current state.

I decided to remove the staled comment since it is not useful for
understanding what the class does.

[ci skip]

Follow up of b988ecb9.

This was added for internal usage, it doesn't need to be public.

Duplicated method name list is no longer needed.

There is no reason `attributes=` doesn't take `assign_attributes`.

This was added in 9bfa13bb, but it is never used from the beginning.

columsn ->
columns

Related to 948b9319

Prevent `ActiveRecord::FinderMethods#limited_ids_for` from using correct primary
key values even if `ORDER BY` columns include other table's primary key.

Fixes #28364.

Actually `reflection.klass` should be valid AR model unless
`polymorphic?`. Previously it worked limitedly by ignoring `NameError`
even if `reflection.klass` is invalid, and our isolated testing depends
on the limited working.
Probably we should also check the klass validity in `check_validity!`
properly. Until that time, I restored the error suppression for now.

Closes #32113.

See 948b9319 for context

Currently the place where we limit what gets sent to the database is in
the implementation for `partial_writes`. We should also be restricting
it to column names when partial writes are turned off.

Note that we're using `&` instead of just defaulting to
`self.class.column_names`, as the instance version of `attribute_names`
does not include attributes which are uninitialized (were not included
in the select clause)

Since #31895, build of 2.5 and AR combination failed.
https://travis-ci.org/rails/rails/jobs/346064349#L1638

It seems to be the reason that model is not loading properly, so I added
require. But I'm not sure if this is correct

This is an alternative of #29722, and revert of #29601 and a1fcbd97.

Currently, association creation and normal association finding doesn't
respect `store_full_sti_class`. But eager loading and preloading respect
the setting. This means that if set `store_full_sti_class = false`
(`true` by default), eager loading and preloading can not find
created polymorphic records.

Association creation and finding should work consistently.

* Add test case for open-ended range.
* Add test case for numeric range for string column.

BC dates are supported by both date and datetime types.

https://www.postgresql.org/docs/current/static/datatype-datetime.html

Since #1097, new datetime allows year zero as 1 BC, but new date does
not. It should be allowed even in new date consistently.

The values infinity and -infinity are supported by both date and
timestamp types.

https://www.postgresql.org/docs/current/static/datatype-datetime.html#DATATYPE-DATETIME-SPECIAL-TABLE

And also, it can not be known whether a value is infinity correctly
unless cast a value.

I've added `QueryAttribute#infinity?` to handle that case.

Closes #27585.

Since #32028, Rails 6 requires Ruby 2.3+.
No longer needed workaround for Ruby 2.2 "private attribute?" warning.

This reverts commit 16f279eb, reversing
changes made to 6c6a30a7.

The config can be named anything, not just default (although all
generated apps will be named default). We can't just delete configs that
don't have a database because that will break three-tier configs. Oh
well.

SQLServerAdapter (gem `activerecord-sqlserver-adapter`) uses square
brackets for quoting column names (e.g. `[id]`). Those brackets must not
be misinterpreted in regular expressions.

Failure:
Expected /SELECT [developers].[id].* FROM developers/ to match "SELECT [developers].[id], [developers].[name], [developers].[salary], [developers].[firm_id], [developers].[mentor_id], [developers].[created_at], [developers].[updated_at], [developers].[created_on], [developers].[updated_on] FROM developers".

We should call methods with `.method_name` not `::method_name`. Fix two
instances of `YAML::load` I found in favor of `YAML.load`.