Fix that #pluck wasn't rescuing ThrowResult, meaning it would blow up when failing to construct_limited_ids_condition.

Cleanup finder methods

In #apply_join_dependency, we can apply the #where in-place because relation is always a new object.

Thanks to the #except we call at the top of the method.

Move the except(:select) inside the construct_limited_ids_condition method to pair it closely with its motivation.

Reject blank order_values within #columns_for_distinct, as the orders aren't used at all on non-postgres adapters.

Fix that #exists? can produce invalid SQL: "SELECT DISTINCT DISTINCT"

Don't try to EXPLAIN select_db calls

The combination of a :uniq => true association and the #distinct call
in #construct_limited_ids_condition combine to create invalid SQL, because
we're explicitly selecting DISTINCT, and also sending #distinct on to AREL,
via the relation#distinct_value.

Rather than build a select distinct clause in #construct_limited_ids_condition,
I set #distinct! and pass just the columns into the select statement.
This requires introducing a #columns_for_distinct method to return the
select columns but not the statement itself.

Can you improve the commit message a little bit? It's good to describe why the change is happening.

Suppose Man has_many interests, and inverse_of is used.

Man.first.interests.first.man will correctly execute two queries,
avoiding the need for a third query when Interest#man is called. This is
because CollectionAssociation#first calls set_inverse_instance.

However Man.first.interests.where("1=1").first.man will execute three
queries, even though this is obviously a subset of the records in the
association.

This is because calling where("1=1") spawns a new Relation object from
the CollectionProxy object, and the Relation has no knowledge of the
association, so it cannot set the inverse instance.

This commit solves the problem by making relations spawned from
CollectionProxies return a new Relation subclass called
AssociationRelation, which does know about associations. Records loaded
from this class will get the inverse instance set properly.

Fixes #5717.

Live commit from La Conf! ✨

[ci skip] document protect_against_forgery? method

remove redundant var

remove variable and fix warning

Require different core extensions correctly.

rails -> Rails [ci skip]

The begin rescue block is specifically to catch LoadError while loading
i18n gem. Other core extensions, under active support, should be
required outside of the begin rescue block.

Fix that JSON and XML exception responses should give the HTTP error message for their status, by default, not the message from the underlying exception

Extraction to enable fixing #10421

* polycb:
  separate identification computation
  separate filters from source code
  if the callbacks are not the same class, they cannot be duplicates
  fix object comparison case
  polymorphic comparison operator

In order to fix #10421 I need to enable merge to take an option
so that relations could be merged without making the last where
condition to win.

That fix would forever reside in 4-0-stable branch and would not be
merged to master since using scope without lambda has been deprecated.

In this commit I have extracted code into a method and I think it
makes code look better. Hence the request to merge it in both
master and 4-0-stable.

If there is any concern then this code can be merged only in
4-0-stable and that would be fine too.