Eagerly loaded collection and singular associations are ignored by the StatementCache, which causes errors when the queries they generate reference columns that were not eagerly loaded.

This commit skips the creation of the StatementCache as a fix for these scenarios.

Fixes #15821.

Reliant on https://github.com/rails/rails/pull/15747 but pulled to a
separate PR to reduce noise. `has_many :through` associations have the
undocumented behavior of automatically detecting counter caches.
However, the way in which it does so is inconsistent with counter caches
everywhere else, and doesn't actually work consistently.

As with normal `has_many` associations, the user should specify the
counter cache on the `belongs_to`, if they'd like it updated.

ActiveRecord::Relation::Merger's filter_binds method does not filter out bind
variables when one of the attribute nodes has a string name, but the other has
a symbol name, even when those names are actually equal.

This can result in there being more bind variables than placeholders in the
generated SQL.  This is particularly an issue for PostgreSQL, where this is
treated as an error.

This patch changes the filter_binds method to make it convert both attribute
names to strings before comparing.

CollectionProxy should be able to reuse the behavior (methods) of its parent class,
but with its own state. This change allows CollectionProxy to use the arel object
corresponding to its association's scope.

Fixes: #12242, #9517, #10240

This reverts commit 70d6e16f, reversing
changes made to ea4db3bc.

Seems to be a code merge done by mistake.

because of an ambiguous column name. This happened if the association
model had a default scope that referenced a third table, and the third
table also referenced the original table (with an identical
foreign_key).

Mysql requires that ambiguous columns are deambiguated by using the full
table.column syntax. Postgresql and Sqlite use a different syntax for
updates altogether (and don't tolerate table.name syntax), so the fix
requires always including the full table.column and discarding it later
for Sqlite and Postgresql.

Suggested by @dhh.

It doesn't affect the generated SQL, so seems reasonable to continue to
allow it as an association option.

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.