Add support for Reply-To field in mail_to helper
Update Active Record's attribute query methods documentation to describe its full behaviour. [ci skip]
Clarify that the word present refers to Object#present?. [ci skip]

Update Active Record's attribute query methods documentation to clarify that whether an attribute is present is based on Object#present?. This gives people a place to go see what the exact definition of presence is. [ci skip]
Remove block from super
Fix connection leak when a thread checks in additional connections.

The code in `ConnectionPool#release` assumed that a single thread only
ever holds a single connection, and thus that releasing a connection
only requires the owning thread_id.

There is a trivial counterexample to this assumption: code that checks
out additional connections from the pool in the same thread. For
instance:

    connection_1 = ActiveRecord::Base.connection
    connection_2 = ActiveRecord::Base.connection_pool.checkout
    ActiveRecord::Base.connection_pool.checkin(connection_2)
    connection_3 = ActiveRecord::Base.connection

At this point, connection_1 has been removed from the
`@reserved_connections` hash, causing a NEW connection to be returned as
connection_3 and the loss of any tracking info on connection_1. As long
as the thread in this example lives, connection_1 will be inaccessible
and un-reapable. If this block of code runs more times than the size of
the connection pool in a single thread, every subsequent connection
attempt will timeout, as all of the available connections have been
leaked.

Reverts parts of 9e457a8654fa89fe329719f88ae3679aefb21e56 and
essentially all of 4367d2f05cbeda855820e25a08353d4b7b3457ac
Merge pull request #18166 from merongivian/search_field_refactor

Remove block from super
Merge pull request #18167 from al2o3cr/checkin_connection_leak

Fix connection leak when a thread checks in additional connections.
Fix syntax warning

This isn't Seattle.rb, @senny. ;)
Refactor a common class to reduce the duplication for `references`

The code for `TableDefinition#references` and
`SchemaStatements#add_reference` were almost identical both
structurally, and in terms of domain knowledge. This removes that
duplication into a common class, using the `Table` API as the expected
interface of its collaborator.
Rails::Application#secrets should be documented.
Don't treat `nil` as changed in serialized types

We were ignoring the `default_value?` escape clause in the serialized
type, which caused the default value to always be treated as changed.

Fixes #18169
Merge pull request #18170 from tgxworld/add_docs_for_rails_application_secrets

[ci skip]
Remove unneeded special case to calculate size for has_many :through

All cases are properly handled in CollectionAssociation
for all subclasses of this association
Merge pull request #18174 from bogdan/cleanup_has_many_though_association_count

Remove unneeded special case to calculate size for has_many :through
proof of concept, need to check in GitHub
second test to warn against reading guides in GitHub
third test to warn against reading guides in GitHub
warn about reading guides in GitHub

References #18148.
removes superfluous regexp group
Clarify that query methods have a custom definition of whether a numeric value is present. [ci skip]

The way Active Record query methods handle numeric values is a special case, and is not part of Rails's standard definition of present. This update attempts to make this more clear in the docs, so that people don't expect Object#present? to return false if used on a number that is zero.