Add _mailer suffix to generated file names.

The build has failed when running the date/time ext tests in isolation
due to the missing extension, so better than adding a require is using
just Ruby in this case.

https://travis-ci.org/rails/rails/jobs/46107954#L1077

fix `attribute` method scoping(i.e. private)

Changing sets -> set [ci-skip]

Updating some minor grammar issue.

Add #weekend?, #next_weekday, and #prev_weekday methods to Date, Time, and DateTime

ref #52f64126

Following the same naming convention used in
controllers and jobs.

Add log_level options to configuration guide

replacing 'attribute' method with an alias

 Fixed typos and wording in ActiveRecord CHANGELOG [ci skip]

Fix lookup of fixtures with non-string(like Fixnum) label

 - Fixtures with non-string labels such as integers should be accessed
   using integer label as key. For eg. pirates(1) or pirates(42).
 - But this results in NotFound error because the label is converted into string before
   looking up into the fixtures hash.
 - After this commit, the label is converted into string only if its a
   symbol.
 - This issue was fount out while adding a test case for
   https://github.com/rails/rails/commit/7b910917.

Add #prev_day and #next_day as counterparts to #yesterday and #tomorrow for Date, Time, and DateTime

`#on_weekend?` returns true if the receiving date/time falls on a Saturday or
Sunday.

`#next_weekday` returns a new date/time representing the next day that does
not fall on a Saturday or Sunday.

`#prev_weekday` returns a new date/time representing the previous day that
does not fall on a Saturday or Sunday.

Improve protect_from_forgery documentation.

removing unecessary default parameter in private method

Documenting 'remove_possible_method' and 'redefine_method' [ci skip]

'_singularize' only ever gets called with one argument

Propagate bind_values from join in subquery

`initialize_internals_callback` will attempt to assign attributes from
the current scope, which will fail if something defined the method
and calls super (meaning it won't hit `method_missing`).

Fixes #18339

Fix rollback of primarykey-less tables

If you have a table without a primary key, and an `after_commit` callback on that table (ie `has_transactional_callbacks?` returns true), then trying to rollback a transaction involving that record would result in “ActiveModel::MissingAttributeError: can't write unknown attribute ``”

Fix I18n regression introduced by #13832

Add Firebird support to test suite

Clean up secure_token_test

Fix TypeError in Fixture creation

Ruby 4.2 started doing `value.gsub('$LABEL', label)` for fixture label interpolation, but you can have have valid YAML where `label` isn't a String. 

For example:

```YAML
0:
  name: John
  email: johndoe@gmail.com
1:
  name: Jane
  email: janedoe@gmail.com
```

This YAML will create a label that is a Fixnum, causing `TypeError: no implicit conversion of Fixnum into String.`