preserve whitespace in textarea tags (HAML/Rails bug)

config/initializers/haml.rb

@@ -1 +1,2 @@
-# Haml::Template.options[:ugly] = true # improve performance in dev
+Haml::Template.options[:format] = :html5
+Haml::Template.options[:ugly]   = true # improve performance in dev

lib/locomotive.rb

@@ -2,6 +2,7 @@ require 'locomotive/version'
 require 'locomotive/core_ext'
 require 'locomotive/configuration'
 require 'locomotive/logger'
+require 'locomotive/haml'
 require 'locomotive/formtastic'
 require 'locomotive/dragonfly'
 require 'locomotive/kaminari'

lib/locomotive/haml.rb

@@ -0,0 +1,34 @@
+require 'haml/helpers/action_view_mods'
+
+module ActionView
+  module Helpers
+    module TagHelper
+
+      # Only preserve whitespace in the tag's content: https://github.com/nex3/haml/pull/503
+      def content_tag_with_haml_and_preserve(name, content_or_options_with_block = nil, *args, &block)
+        Rails.logger.debug("[content_tag_with_haml_and_preserve / ENGINE] #{name} / #{respond_to?(:content_tag_with_haml)} / #{respond_to?(:content_tag_without_haml)}")
+
+        return content_tag_without_haml(name, content_or_options_with_block, *args, &block) unless is_haml?
+
+        preserve = haml_buffer.options[:preserve].include?(name.to_s)
+
+        if block_given?
+          if block_is_haml?(block) && preserve
+            content_tag_without_haml(name, content_or_options_with_block, *args) {preserve(&block)}
+          else
+            content_tag_without_haml(name, content_or_options_with_block, *args, &block)
+          end
+        else
+          if preserve && content_or_options_with_block
+            content_or_options_with_block = Haml::Helpers.preserve(content_or_options_with_block)
+          end
+          content_tag_without_haml(name, content_or_options_with_block, *args, &block)
+        end
+      end
+
+      alias_method :content_tag_without_haml_and_preserve, :content_tag
+      alias_method :content_tag, :content_tag_with_haml_and_preserve
+      alias_method :content_tag_with_haml, :content_tag_with_haml_and_preserve
+    end
+  end
+end

spec/dummy/config/initializers/haml.rb

@@ -1 +1,2 @@
+Haml::Template.options[:format] = :html5
 Haml::Template.options[:ugly]   = true # improve performance in dev