lib/rubocop/cop/style/line_end_concatenation.rb in rubocop-0.21.0 vs lib/rubocop/cop/style/line_end_concatenation.rb in rubocop-0.22.0

@@ -18,11 +18,11 @@
       #   # good
       #   some_str = 'ala' \
       #              'bala'
       #
       class LineEndConcatenation < Cop
-        MSG = 'Use \\ instead of + or << to concatenate those strings.'
+        MSG = 'Use `\\` instead of `+` or `<<` to concatenate those strings.'
 
         def on_send(node)
           add_offense(node, :selector) if offending_node?(node)
         end
 
@@ -33,19 +33,22 @@
           end
         end
 
         private
 
+        def concat?(method)
+          [:+, :<<].include?(method)
+        end
+
         def offending_node?(node)
-          receiver, method, arg = *node
+          receiver, method, first_arg = *node
 
-          # TODO: Report Emacs bug.
-          return false unless [:+, :<<].include?(method)
+          return false unless concat?(method)
 
-          return false unless string_type?(receiver)
+          return false unless final_node_is_string_type?(receiver)
 
-          return false unless string_type?(arg)
+          return false unless root_node_is_string_type?(first_arg)
 
           expression = node.loc.expression.source
           concatenator_at_line_end?(expression)
         end
 
@@ -54,12 +57,32 @@
           expression =~ /.+(\+|<<)\s*$/
         end
 
         def string_type?(node)
           return false unless [:str, :dstr].include?(node.type)
+          # strings like __FILE__ are of no interest
+          return false unless node.loc.respond_to?(:begin)
 
           # we care only about quotes-delimited literals
           node.loc.begin && ["'", '"'].include?(node.loc.begin.source)
+        end
+
+        def final_node_is_string_type?(node)
+          if node.type == :send
+            _, method, first_arg = *node
+            concat?(method) && final_node_is_string_type?(first_arg)
+          else
+            string_type?(node)
+          end
+        end
+
+        def root_node_is_string_type?(node)
+          if node.type == :send
+            receiver, method, _ = *node
+            concat?(method) && root_node_is_string_type?(receiver)
+          else
+            string_type?(node)
+          end
         end
       end
     end
   end
 end