This reverts commit 761bc751.

This commit wasn't fixing any issue just using the same table for
different models with different primary keys.

It doesn't serve much purpose now that ActiveRecord::Base.all returns a
Relation.

The code is moved to active_record_deprecated_finders.

interpolation is no longer a thing separate from "normal" assoc
conditions.

Don't use this:

    scope :red, where(color: 'red')
    default_scope where(color: 'red')

Use this:

    scope :red, -> { where(color: 'red') }
    default_scope { where(color: 'red') }

The former has numerous issues. It is a common newbie gotcha to do
the following:

    scope :recent, where(published_at: Time.now - 2.weeks)

Or a more subtle variant:

    scope :recent, -> { where(published_at: Time.now - 2.weeks) }
    scope :recent_red, recent.where(color: 'red')

Eager scopes are also very complex to implement within Active
Record, and there are still bugs. For example, the following does
not do what you expect:

    scope :remove_conditions, except(:where)
    where(...).remove_conditions # => still has conditions

:strict

Fixes #2832

Un-deprecate using 'default_scope' as a macro, but if you are calling the macro multiple times that will give deprecation warnings, and in 3.2 we will simply overwrite the default scope when you call the macro multiple times.

Revert "Deprecate defining scopes with a callable (lambda, proc, etc) via the scope class method. Just define a class method yourself instead."

This reverts commit f0e198bf.

Conflicts:

	activerecord/test/models/post.rb

Deprecate defining scopes with a callable (lambda, proc, etc) via the scope class method. Just define a class method yourself instead.

Deprecated support for passing hashes and relations to default_scope, in favour of defining a 'default_scope' class method in the model. See the CHANGELOG for more details.

Add a test for STI on the through where the through is nested, and change the code which support this

Allow building and then later saving has_many :through records, such that the join record is automatically saved too. This requires the :inverse_of option to be set on the source association in the join model. See the CHANGELOG for details. [#4329 state:resolved]

Ensure that association_ids uses the correct attribute where the association is a has_many :through with a :primary_key option on the source reflection. [#6376 state:resolved]

Add interpolation of association conditions back in, in the form of proc { ... } rather than instance_eval-ing strings

Correctly update counter caches on deletion for has_many :through [#2824 state:resolved]. Also fixed a bunch of other counter cache bugs in the process, as once I fixed this one others started appearing like nobody's business.

Let AssociationCollection#find use #scoped to do its finding. Note that I am removing test_polymorphic_has_many_going_through_join_model_with_disabled_include, since this specifies different behaviour for an association than for a regular scope. It seems reasonable to expect scopes and association proxies to behave in roughly the same way rather than having subtle differences.

has_many associations with :dependent => :delete_all should update the counter cache when deleting records

Fix problem where wrong keys are used in JoinAssociation when an association goes :through a belongs_to [#2801 state:resolved]

Add support for nested through associations in JoinAssociation. Hence Foo.joins(:bar) will work for through associations. There is some duplicated code now, which will be refactored.