[Fix rubocop#2294] Allow regex with options in StringReplacement

CHANGELOG.md

@@ -25,6 +25,7 @@
 * [#2284](https://github.com/bbatsov/rubocop/issues/2284): Fix result cache being shared between ruby versions. ([@miquella][])
 * [#2285](https://github.com/bbatsov/rubocop/issues/2285): Fix `ConfigurableNaming#class_emitter_method?` error when handling singleton class methods. ([@palkan][])
 * [#2295](https://github.com/bbatsov/rubocop/issues/2295): Fix Performance/Detect autocorrect to handle rogue newlines. ([@palkan][])
+* [#2294](https://github.com/bbatsov/rubocop/issues/2294): Do not register an offense in `Performance/StringReplacement` for regex with options. ([@rrosenblum][])
 
 ## 0.34.2 (21/09/2015)
 

lib/rubocop/cop/performance/string_replacement.rb

@@ -32,16 +32,17 @@ class StringReplacement < Cop
         def on_send(node)
           _string, method, first_param, second_param = *node
           return unless GSUB_METHODS.include?(method)
-          return unless second_param && second_param.str_type?
+          return unless string?(second_param)
           return unless DETERMINISTIC_TYPES.include?(first_param.type)
 
-          first_source = first_source(first_param)
+          first_source, options = first_source(first_param)
           second_source, = *second_param
 
           return if first_source.nil?
 
           if regex?(first_param)
             return unless first_source =~ DETERMINISTIC_REGEX
+            return if options
           end
 
           return if first_source.length != 1
@@ -53,7 +54,7 @@ def on_send(node)
 
         def autocorrect(node)
           _string, method, first_param, second_param = *node
-          first_source = first_source(first_param)
+          first_source, = first_source(first_param)
           second_source, = *second_param
           replacement_method = replacement_method(method,
                                                   first_source,
@@ -74,17 +75,21 @@ def autocorrect(node)
 
         private
 
+        def string?(node)
+          node && node.str_type?
+        end
+
         def first_source(first_param)
           case first_param.type
           when :regexp, :send
             return nil unless regex?(first_param)
 
-            source, = extract_source(first_param)
+            source, options = extract_source(first_param)
           when :str
             source, = *first_param
           end
 
-          source
+          [source, options]
         end
 
         def extract_source(node)
@@ -97,9 +102,10 @@ def extract_source(node)
         end
 
         def source_from_regex_literal(node)
-          regex, = *node
+          regex, options = *node
           source, = *regex
-          source
+          options, = *options
+          [source, options]
         end
 
         def source_from_regex_constructor(node)

spec/rubocop/cop/performance/string_replacement_spec.rb

@@ -85,6 +85,18 @@
         expect(cop.messages).to be_empty
       end
 
+      it 'allows regex literals with options' do
+        inspect_source(cop, "'abc'.#{method}(/a/i, '1')")
+
+        expect(cop.messages).to be_empty
+      end
+
+      it 'allows regex with options' do
+        inspect_source(cop, "'abc'.#{method}(Regexp.new(/a/i), '1')")
+
+        expect(cop.messages).to be_empty
+      end
+
       it 'allows empty string pattern' do
         inspect_source(cop, "'abc'.gsub('', '1')")