Don't enforce UTF-8 by default

With the disabling of TLS 1.0 by most major websites, continuing to run
IE8 or lower becomes increasingly difficult so default to not enforcing
UTF-8 encoding as it's not relevant to other browsers.

7 files changed, 152 insertions, 3 deletions

diff --git a/actionview/CHANGELOG.md b/actionview/CHANGELOG.md
index fef108aad8..896f79fef9 100644
--- a/actionview/CHANGELOG.md
+++ b/actionview/CHANGELOG.md
@@ -1,5 +1,13 @@
 ## Rails 6.0.0.alpha (Unreleased) ##
 
+*   Don't enforce UTF-8 by default
+
+    With the disabling of TLS 1.0 by most major websites, continuing to run
+    IE8 or lower becomes increasingly difficult so default to not enforcing
+    UTF-8 encoding as it's not relevant to other browsers.
+
+    *Andrew White*
+
 *   Change translation key of `submit_tag` from `module_name_class_name` to `module_name/class_name`.
 
     *Rui Onodera*
diff --git a/actionview/lib/action_view/helpers/form_helper.rb b/actionview/lib/action_view/helpers/form_helper.rb
index e27628f58b..65143efabb 100644
--- a/actionview/lib/action_view/helpers/form_helper.rb
+++ b/actionview/lib/action_view/helpers/form_helper.rb
@@ -1519,10 +1519,10 @@ module ActionView
 
       private
         def html_options_for_form_with(url_for_options = nil, model = nil, html: {}, local: !form_with_generates_remote_forms,
-          skip_enforcing_utf8: false, **options)
+          skip_enforcing_utf8: nil, **options)
           html_options = options.slice(:id, :class, :multipart, :method, :data).merge(html)
           html_options[:method] ||= :patch if model.respond_to?(:persisted?) && model.persisted?
-          html_options[:enforce_utf8] = !skip_enforcing_utf8
+          html_options[:enforce_utf8] = !skip_enforcing_utf8 unless skip_enforcing_utf8.nil?
 
           html_options[:enctype] = "multipart/form-data" if html_options.delete(:multipart)
 
diff --git a/actionview/lib/action_view/helpers/form_tag_helper.rb b/actionview/lib/action_view/helpers/form_tag_helper.rb
index e86e18dd78..5a8b8555a0 100644
--- a/actionview/lib/action_view/helpers/form_tag_helper.rb
+++ b/actionview/lib/action_view/helpers/form_tag_helper.rb
@@ -22,6 +22,8 @@ module ActionView
       mattr_accessor :embed_authenticity_token_in_remote_forms
       self.embed_authenticity_token_in_remote_forms = nil
 
+      mattr_accessor :default_enforce_utf8, default: true
+
       # Starts a form tag that points the action to a url configured with <tt>url_for_options</tt> just like
       # ActionController::Base#url_for. The method for the form defaults to POST.
       #
@@ -866,7 +868,7 @@ module ActionView
               })
             end
 
-          if html_options.delete("enforce_utf8") { true }
+          if html_options.delete("enforce_utf8") { default_enforce_utf8 }
             utf8_enforcer_tag + method_tag
           else
             method_tag
diff --git a/actionview/lib/action_view/railtie.rb b/actionview/lib/action_view/railtie.rb
index 73dfb267bb..12bdc642d4 100644
--- a/actionview/lib/action_view/railtie.rb
+++ b/actionview/lib/action_view/railtie.rb
@@ -9,6 +9,7 @@ module ActionView
     config.action_view = ActiveSupport::OrderedOptions.new
     config.action_view.embed_authenticity_token_in_remote_forms = nil
     config.action_view.debug_missing_translation = true
+    config.action_view.default_enforce_utf8 = nil
 
     config.eager_load_namespaces << ActionView
 
@@ -35,6 +36,15 @@ module ActionView
       end
     end
 
+    initializer "action_view.default_enforce_utf8" do |app|
+      ActiveSupport.on_load(:action_view) do
+        default_enforce_utf8 = app.config.action_view.delete(:default_enforce_utf8)
+        unless default_enforce_utf8.nil?
+          ActionView::Helpers::FormTagHelper.default_enforce_utf8 = default_enforce_utf8
+        end
+      end
+    end
+
     initializer "action_view.logger" do
       ActiveSupport.on_load(:action_view) { self.logger ||= Rails.logger }
     end
diff --git a/actionview/test/template/form_helper/form_with_test.rb b/actionview/test/template/form_helper/form_with_test.rb
index 42905b1ec5..6b65d740eb 100644
--- a/actionview/test/template/form_helper/form_with_test.rb
+++ b/actionview/test/template/form_helper/form_with_test.rb
@@ -14,6 +14,16 @@ class FormWithTest < ActionView::TestCase
   teardown do
     ActionView::Helpers::FormHelper.form_with_generates_ids = @old_value
   end
+
+  private
+    def with_default_enforce_utf8(value)
+      old_value = ActionView::Helpers::FormTagHelper.default_enforce_utf8
+      ActionView::Helpers::FormTagHelper.default_enforce_utf8 = value
+
+      yield
+    ensure
+      ActionView::Helpers::FormTagHelper.default_enforce_utf8 = old_value
+    end
 end
 
 class FormWithActsLikeFormTagTest < FormWithTest
@@ -111,6 +121,24 @@ class FormWithActsLikeFormTagTest < FormWithTest
     assert_predicate actual, :html_safe?
   end
 
+  def test_form_with_default_enforce_utf8_false
+    with_default_enforce_utf8 false do
+      actual = form_with
+      expected = whole_form("http://www.example.com", skip_enforcing_utf8: true)
+      assert_dom_equal expected, actual
+      assert_predicate actual, :html_safe?
+    end
+  end
+
+  def test_form_with_default_enforce_utf8_true
+    with_default_enforce_utf8 true do
+      actual = form_with
+      expected = whole_form("http://www.example.com", skip_enforcing_utf8: false)
+      assert_dom_equal expected, actual
+      assert_predicate actual, :html_safe?
+    end
+  end
+
   def test_form_with_with_block_in_erb
     output_buffer = render_erb("<%= form_with(url: 'http://www.example.com') do %>Hello world!<% end %>")
 
@@ -819,6 +847,34 @@ class FormWithActsLikeFormForTest < FormWithTest
     assert_dom_equal expected, output_buffer
   end
 
+  def test_form_with_default_enforce_utf8_true
+    with_default_enforce_utf8 true do
+      form_with(scope: :post) do |f|
+        concat f.text_field(:title)
+      end
+
+      expected = whole_form("/", skip_enforcing_utf8: false) do
+        "<input name='post[title]' type='text' value='Hello World' id='post_title' />"
+      end
+
+      assert_dom_equal expected, output_buffer
+    end
+  end
+
+  def test_form_with_default_enforce_utf8_false
+    with_default_enforce_utf8 false do
+      form_with(scope: :post) do |f|
+        concat f.text_field(:title)
+      end
+
+      expected = whole_form("/", skip_enforcing_utf8: true) do
+        "<input name='post[title]' type='text' value='Hello World' id='post_title' />"
+      end
+
+      assert_dom_equal expected, output_buffer
+    end
+  end
+
   def test_form_with_without_object
     form_with(scope: :post, id: "create-post") do |f|
       concat f.text_field(:title)
@@ -2291,4 +2347,13 @@ class FormWithActsLikeFormForTest < FormWithTest
     ensure
       I18n.locale = old_locale
     end
+
+    def with_default_enforce_utf8(value)
+      old_value = ActionView::Helpers::FormTagHelper.default_enforce_utf8
+      ActionView::Helpers::FormTagHelper.default_enforce_utf8 = value
+
+      yield
+    ensure
+      ActionView::Helpers::FormTagHelper.default_enforce_utf8 = old_value
+    end
 end
diff --git a/actionview/test/template/form_helper_test.rb b/actionview/test/template/form_helper_test.rb
index a55811b67b..5244204e42 100644
--- a/actionview/test/template/form_helper_test.rb
+++ b/actionview/test/template/form_helper_test.rb
@@ -1995,6 +1995,34 @@ class FormHelperTest < ActionView::TestCase
     assert_dom_equal expected, output_buffer
   end
 
+  def test_form_for_default_enforce_utf8_false
+    with_default_enforce_utf8 false do
+      form_for(:post) do |f|
+        concat f.text_field(:title)
+      end
+
+      expected = whole_form("/", nil, nil, enforce_utf8: false) do
+        "<input name='post[title]' type='text' id='post_title' value='Hello World' />"
+      end
+
+      assert_dom_equal expected, output_buffer
+    end
+  end
+
+  def test_form_for_default_enforce_utf8_true
+    with_default_enforce_utf8 true do
+      form_for(:post) do |f|
+        concat f.text_field(:title)
+      end
+
+      expected = whole_form("/", nil, nil, enforce_utf8: true) do
+        "<input name='post[title]' type='text' id='post_title' value='Hello World' />"
+      end
+
+      assert_dom_equal expected, output_buffer
+    end
+  end
+
   def test_form_for_with_remote_in_html
     form_for(@post, url: "/", html: { remote: true, id: "create-post", method: :patch }) do |f|
       concat f.text_field(:title)
@@ -3569,4 +3597,13 @@ class FormHelperTest < ActionView::TestCase
     ensure
       I18n.locale = old_locale
     end
+
+    def with_default_enforce_utf8(value)
+      old_value = ActionView::Helpers::FormTagHelper.default_enforce_utf8
+      ActionView::Helpers::FormTagHelper.default_enforce_utf8 = value
+
+      yield
+    ensure
+      ActionView::Helpers::FormTagHelper.default_enforce_utf8 = old_value
+    end
 end
diff --git a/actionview/test/template/form_tag_helper_test.rb b/actionview/test/template/form_tag_helper_test.rb
index 0d9bf77f98..a3500a7eb3 100644
--- a/actionview/test/template/form_tag_helper_test.rb
+++ b/actionview/test/template/form_tag_helper_test.rb
@@ -152,6 +152,24 @@ class FormTagHelperTest < ActionView::TestCase
     assert_predicate actual, :html_safe?
   end
 
+  def test_form_tag_default_enforce_utf8_false
+    with_default_enforce_utf8 false do
+      actual = form_tag({})
+      expected = whole_form("http://www.example.com", enforce_utf8: false)
+      assert_dom_equal expected, actual
+      assert_predicate actual, :html_safe?
+    end
+  end
+
+  def test_form_tag_default_enforce_utf8_true
+    with_default_enforce_utf8 true do
+      actual = form_tag({})
+      expected = whole_form("http://www.example.com", enforce_utf8: true)
+      assert_dom_equal expected, actual
+      assert_predicate actual, :html_safe?
+    end
+  end
+
   def test_form_tag_with_block_in_erb
     output_buffer = render_erb("<%= form_tag('http://www.example.com') do %>Hello world!<% end %>")
 
@@ -782,4 +800,13 @@ class FormTagHelperTest < ActionView::TestCase
     def root_elem(rendered_content)
       Nokogiri::HTML::DocumentFragment.parse(rendered_content).children.first # extract from nodeset
     end
+
+    def with_default_enforce_utf8(value)
+      old_value = ActionView::Helpers::FormTagHelper.default_enforce_utf8
+      ActionView::Helpers::FormTagHelper.default_enforce_utf8 = value
+
+      yield
+    ensure
+      ActionView::Helpers::FormTagHelper.default_enforce_utf8 = old_value
+    end
 end