*   Update `select_tag` to work correctly with `:include_blank` option passing a string.

    Fixes #16483.

    *Frank Groeneveld*

*   Changed the meaning of `render "foo/bar"`.

    Previously, calling `render "foo/bar"` in a controller action is equivalent
    to `render file: "foo/bar"`. In Rails 4.2, this has been changed to mean
    `render template: "foo/bar"` instead. If you need to render a file, please
    change your code to use the explicit form (`render file: "foo/bar"`) instead.

    *Jeremy Jackson*

*   Add support for ARIA attributes in tags.

    Example:

        <%= f.text_field :name, aria: { required: "true", hidden: "false" } %>

    now generates:

         <input aria-hidden="false" aria-required="true" id="user_name" name="user[name]" type="text">

    *Paola Garcia Casadiego*

*   Provide a `builder` object when using the `label` form helper in block form.

    The new `builder` object responds to `translation`, allowing I18n fallback support
    when you want to customize how a particular label is presented.

    *Alex Robbin*

*   Add I18n support for input/textarea placeholder text.

    Placeholder I18n follows the same convention as `label` I18n.

    *Alex Robbin*

*   Fix that render layout: 'messages/layout' should also be added to the dependency tracker tree.

    *DHH*

*   Add `PartialIteration` object used when rendering collections.

    The iteration object is available as the local variable
    `#{template_name}_iteration` when rendering partials with collections.

    It gives access to the `size` of the collection being iterated over,
    the current `index` and two convenience methods `first?` and `last?`.

    *Joel Junström*, *Lucas Uyezu*

*   Return an absolute instead of relative path from an asset url in the case
    of the `asset_host` proc returning nil.

    *Jolyon Pawlyn*

*   Fix `html_escape_once` to properly handle hex escape sequences (e.g. &#x1a2b;).

    *John F. Douthat*

*   Added String support for min and max properties for date field helpers.

    *Todd Bealmear*

*   The `highlight` helper now accepts a block to be used instead of the `highlighter`
    option.

    *Lucas Mazza*

*   The `except` and `highlight` helpers now accept regular expressions.

    *Jan Szumiec*

*   Flatten the array parameter in `safe_join`, so it behaves consistently with
    `Array#join`.

    *Paul Grayson*

*   Honor `html_safe` on array elements in tag values, as we do for plain string
    values.

    *Paul Grayson*

*   Add `ActionView::Template::Handler.unregister_template_handler`.

    It performs the opposite of `ActionView::Template::Handler.register_template_handler`.

    *Zuhao Wan*

*   Bring `cache_digest` rake tasks up-to-date with the latest API changes.

    *Jiri Pospisil*

*   Allow custom `:host` option to be passed to `asset_url` helper that
    overwrites `config.action_controller.asset_host` for particular asset.

    *Hubert Łępicki*

*   Deprecate `AbstractController::Base.parent_prefixes`.
    Override `AbstractController::Base.local_prefixes` when you want to change
    where to find views.

    *Nick Sutterer*

*   Take label values into account when doing I18n lookups for model attributes.

    The following:

        # form.html.erb
        <%= form_for @post do |f| %>
          <%= f.label :type, value: "long" %>
        <% end %>

        # en.yml
        en:
          activerecord:
            attributes:
              post/long: "Long-form Post"

    Used to simply return "long", but now it will return "Long-form
    Post".

    *Joshua Cody*

*   Change `asset_path` to use File.join to create proper paths:

    Before:

        https://some.host.com//assets/some.js

    After:

        https://some.host.com/assets/some.js

    *Peter Schröder*

*   Change `favicon_link_tag` default mimetype from `image/vnd.microsoft.icon` to
    `image/x-icon`.

    Before:

        # => favicon_link_tag 'myicon.ico'
        <link href="/assets/myicon.ico" rel="shortcut icon" type="image/vnd.microsoft.icon" />

    After:

        # => favicon_link_tag 'myicon.ico'
        <link href="/assets/myicon.ico" rel="shortcut icon" type="image/x-icon" />

    *Geoffroy Lorieux*

*   Remove wrapping div with inline styles for hidden form fields.

    We are dropping HTML 4.01 and XHTML strict compliance since input tags directly
    inside a form are valid HTML5, and the absence of inline styles help in validating
    for Content Security Policy.

    *Joost Baaij*

*   `collection_check_boxes` respects `:index` option for the hidden field name.

    Fixes #14147.

    *Vasiliy Ermolovich*

*   `date_select` helper with option `with_css_classes: true` does not overwrite other classes.

    *Izumi Wong-Horiuchi*

*   `number_to_percentage` does not crash with `Float::NAN` or `Float::INFINITY`
    as input.

    Fixes #14405.

    *Yves Senn*

*   Add `include_hidden` option to `collection_check_boxes` helper.

    *Vasiliy Ermolovich*

*   Fixed a problem where the default options for the `button_tag` helper are not
    applied correctly.

    Fixes #14254.

    *Sergey Prikhodko*

*   Take variants into account when calculating template digests in ActionView::Digestor.

    The arguments to ActionView::Digestor#digest are now being passed as a hash
    to support variants and allow more flexibility in the future. The support for
    regular (required) arguments is deprecated and will be removed in Rails 5.0 or later.

    *Piotr Chmolowski, Łukasz Strzałkowski*

Please check [4-1-stable](https://github.com/rails/rails/blob/4-1-stable/actionview/CHANGELOG.md) for previous changes.