Fix interpolation in comments

Fix #1107

lib/haml/compiler/comment_compiler.rb

@@ -14,7 +14,7 @@ module Haml
 
       def compile_html_comment(node, &block)
         if node.children.empty?
-          [:html, :comment, [:static, " #{node.value[:text]} "]]
+          [:html, :comment, compile_text(node)]
         else
           [:html, :comment, yield(node)]
         end
@@ -28,12 +28,24 @@ module Haml
 
         content =
           if node.children.empty?
-            [:static, " #{node.value[:text]} "]
+            compile_text(node)
           else
             yield(node)
           end
         [:html, :condcomment, condition, content, node.value[:revealed]]
       end
+
+      def compile_text(node)
+        text =
+          if node.value[:parse]
+            # Just always escaping the result for safety. We could respect
+            # escape_html, but I don't see any use case for it.
+            [:escape, true, [:dynamic, node.value[:text]]]
+          else
+            [:static, node.value[:text]]
+          end
+        [:multi, [:static, ' '], text, [:static, ' ']]
+      end
     end
   end
 end

test/haml/engine/comment_test.rb

@@ -6,6 +6,10 @@ describe Haml::Engine do
       assert_render(%Q|<!-- comments -->\n|, '/ comments')
     end
 
+    it 'renders intepolation' do
+      assert_render(%Q|<!-- comments -->\n|, '/ #{"comments"}')
+    end
+
     it 'strips html comment ignoring around spcaes' do
       assert_render(%Q|<!-- comments -->\n|, '/   comments    ')
     end
@@ -61,6 +65,7 @@ describe Haml::Engine do
           world
       HAML
     end
+
     it 'renders conditional comment' do
       assert_render(<<-HTML.unindent, <<-'HAML'.unindent)
         <!--[if lt IE 9]>