Make Style/RedundantPercentQ handle multiline source safely

changelog/mark_style_redundant_percent_q_as_unsafe_autocorrect.md

@@ -0,0 +1,2 @@
+
+* [#12780](https://github.com/rubocop/rubocop/pulls/12784): Mark `Style/RedundantPercentQ` as unsafe autocorrect ([@boardfish][])

lib/rubocop/cop/style/redundant_percent_q.rb

@@ -53,13 +53,17 @@ def check(node)
           return if interpolated_quotes?(node) || allowed_percent_q?(node)
 
           add_offense(node) do |corrector|
-            delimiter = /^%Q[^"]+$|'/.match?(node.source) ? QUOTE : SINGLE_QUOTE
+            delimiter = delimiter_for(node.source)
 
             corrector.replace(node.loc.begin, delimiter)
             corrector.replace(node.loc.end, delimiter)
           end
         end
 
+        def delimiter_for(source)
+          /\A%Q[^"]+\z|'/.match?(source) ? QUOTE : SINGLE_QUOTE
+        end
+
         def interpolated_quotes?(node)
           node.source.include?(SINGLE_QUOTE) && node.source.include?(QUOTE)
         end

spec/rubocop/cop/style/redundant_percent_q_spec.rb

@@ -142,6 +142,21 @@
           'boogers'
       RUBY
     end
+
+    it 'autocorrects safely for strings containing Ruby 1.6 hash syntax' do
+      expect_offense(<<~'RUBY')
+        %Q(
+        ^^^ Use `%Q` only for strings that contain both single [...]
+          { "foo" => "bar" }
+        )
+      RUBY
+
+      expect_correction(<<~'RUBY')
+        '
+          { "foo" => "bar" }
+        '
+      RUBY
+    end
   end
 
   it 'accepts a heredoc string that contains %q' do