Fix bug, when ':dependent => :destroy' option violates foreign key constraints, issue #12380
Moved explanation of `--mountable` option up

The example code uses `--mountable`. In previous version this was followed by an explanation of the `--full` option, which doesn't make sense. Later on in the text this is better explained. I moved this explanation up without repeating too much.
skip migration check if adapter doesn't support it
Added missing test case for migrations when using sql structure
Prevent state leak.
Remove redundant code.
Refactor determination of max updated timestamp

`[].max # => nil`
[ci skip] Add note about type modifiers that cannot be specified in command line.
Merge pull request #15602 from JuanitoFatas/doc/type-modifier

[ci skip] Add note about type modifiers that cannot be specified in command line.
ActiveRecord::FinderMethods.find passes proc parameter #15382
Merge pull request #15584 from jamesyang124/issue_15382

ActiveRecord::FinderMethods.find doesn't pass proc parameter to array

Manual merge of #15584.

Closes #15584.
remove depricated Validatior#setup
[ci skip] Rename: Rails Database Migration to Active Record Migration.

This will need to setup permanent redirect for the old guide.
Merge pull request #15604 from JuanitoFatas/doc/migration

[ci skip] Rename: Rails Database Migration to Active Record Migration.
docs, refactor docs about column modifiers. [ci skip] [Matthew Draper & Yves Senn]

This is a follow up to #15602 which rendered the guides in a weird state:

  >  You can also specify some options just after the field type between curly
     braces. You can use the following modifiers:

  >  `null`         Allows or disallows `NULL` values in the column.

  >  NOTE: `null` and `default` cannot be specified via command line.

The modifiers are now moved into a separate section. The generator
simply referes to that section.

Related to #15583.

/cc @JuanitoFatas
test, fix typo, `create_index` does not exist.
Fix cache_digest rake tasks

Bring cache_digests:* rake tasks up-to-date with the API changes introduced in
637bb726cac60aaa1f7e482836458aa73e17fbb7
Inline PG array type casting helper
Merge pull request #15607 from sgrif/sg-array-type-cast

Inline PG array type casting helper
Merge pull request #15605 from mekishizufu/fix_cache_digests_rake_tasks

Fix cache_digest rake tasks