1 files changed, 27 insertions, 1 deletions
diff --git a/actionview/lib/action_view/template/handlers.rb b/actionview/lib/action_view/template/handlers.rb
index 7ec76dcc3f..f2a2341b8e 100644
--- a/actionview/lib/action_view/template/handlers.rb
+++ b/actionview/lib/action_view/template/handlers.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "active_support/deprecation"
+
 module ActionView #:nodoc:
   # = Action View Template Handlers
   class Template #:nodoc:
@@ -14,7 +16,7 @@ module ActionView #:nodoc:
         base.register_template_handler :erb, ERB.new
         base.register_template_handler :html, Html.new
         base.register_template_handler :builder, Builder.new
-        base.register_template_handler :ruby, :source.to_proc
+        base.register_template_handler :ruby, lambda { |_, source| source }
       end
 
       @@template_handlers = {}
@@ -24,11 +26,35 @@ module ActionView #:nodoc:
         @@template_extensions ||= @@template_handlers.keys
       end
 
+      class LegacyHandlerWrapper < SimpleDelegator # :nodoc:
+        def call(view, source)
+          __getobj__.call(ActionView::Template::LegacyTemplate.new(view, source))
+        end
+      end
+
       # Register an object that knows how to handle template files with the given
       # extensions. This can be used to implement new template types.
       # The handler must respond to +:call+, which will be passed the template
       # and should return the rendered template as a String.
       def register_template_handler(*extensions, handler)
+        params = if handler.is_a?(Proc)
+          handler.parameters
+        else
+          handler.method(:call).parameters
+        end
+
+        unless params.find_all { |type, _| type == :req }.length >= 2
+          ActiveSupport::Deprecation.warn <<~eowarn
+          Single arity template handlers are deprecated.  Template handlers must
+          now accept two parameters, the view object and the source for the view object.
+          Change:
+            >> #{handler.class}#call(#{params.map(&:last).join(", ")})
+          To:
+            >> #{handler.class}#call(#{params.map(&:last).join(", ")}, source)
+          eowarn
+          handler = LegacyHandlerWrapper.new(handler)
+        end
+
         raise(ArgumentError, "Extension is required") if extensions.empty?
         extensions.each do |extension|
           @@template_handlers[extension.to_sym] = handler