[Haml] Make sure HTML5 custom data attributes don't lead to duplicate attrs.

lib/haml/precompiler.rb

@@ -542,6 +542,12 @@ END
       quote_escape = attr_wrapper == '"' ? """ : "'"
       other_quote_char = attr_wrapper == '"' ? "'" : '"'
 
+      if attributes['data'].is_a?(Hash)
+        attributes = attributes.dup
+        attributes =
+          Haml::Util.map_keys(attributes.delete('data')) {|name| "data-#{name}"}.merge(attributes)
+      end
+
       result = attributes.collect do |attr, value|
         next if value.nil?
 
@@ -553,9 +559,6 @@ END
           next " #{attr}=#{attr_wrapper}#{attr}#{attr_wrapper}"
         elsif value == false
           next
-        elsif attr == 'data' && value.is_a?(Hash)
-          next build_attributes(is_html, attr_wrapper,
-            Haml::Util.map_keys(value) {|name| "data-#{name}"})
         end
 
         value = Haml::Helpers.preserve(Haml::Helpers.escape_once(value.to_s))

test/haml/engine_test.rb

@@ -1203,7 +1203,15 @@ SASS
       render("%div{:data => {:one_plus_one => 1+1}}"))
 
     assert_equal("<div data-foo='Here&apos;s a \"quoteful\" string.'></div>\n",
-      render(%{%div{:data => {:foo => %{Here's a "quoteful" string.}}}}))
+      render(%{%div{:data => {:foo => %{Here's a "quoteful" string.}}}})) #'
+  end
+
+  def test_html5_data_attributes_with_multiple_defs
+    # Should always use the more-explicit attribute
+    assert_equal("<div data-foo='second'></div>\n",
+      render("%div{:data => {:foo => 'first'}, 'data-foo' => 'second'}"))
+    assert_equal("<div data-foo='first'></div>\n",
+      render("%div{'data-foo' => 'first', :data => {:foo => 'second'}}"))
   end
 
   # New attributes