[Fix rubocop#9698] Fix an error for Style/StructInheritance

Fixes rubocop#9698.

This PR fixes an error for `Style/StructInheritance` when extending instance of
`Struct` without `do` ... `end` and class body is empty and single line definition.

changelog/fix_an_error_for_style_struct_inheritance.md

@@ -0,0 +1 @@
+* [#9698](https://github.com/rubocop/rubocop/issues/9698): Fix an error for `Style/StructInheritance` when extending instance of `Struct` without `do` ... `end` and class body is empty and single line definition. ([@koic][])

lib/rubocop/cop/style/struct_inheritance.rb

@@ -49,11 +49,19 @@ def correct_parent(parent, corrector)
           if parent.block_type?
             corrector.remove(range_with_surrounding_space(range: parent.loc.end, newlines: false))
           elsif (class_node = parent.parent).body.nil?
-            corrector.remove(range_by_whole_lines(class_node.loc.end, include_final_newline: true))
+            corrector.remove(range_for_empty_class_body(class_node, parent))
           else
             corrector.insert_after(parent.loc.expression, ' do')
           end
         end
+
+        def range_for_empty_class_body(class_node, struct_new)
+          if class_node.single_line?
+            range_between(struct_new.source_range.end_pos, class_node.source_range.end_pos)
+          else
+            range_by_whole_lines(class_node.loc.end, include_final_newline: true)
+          end
+        end
       end
     end
   end

spec/rubocop/cop/style/struct_inheritance_spec.rb

@@ -56,6 +56,17 @@ class Person < Struct.new(:first_name, :last_name)
     RUBY
   end
 
+  it 'registers an offense when extending instance of Struct without `do` ... `end` and class body is empty and single line definition' do
+    expect_offense(<<~RUBY)
+      class Person < Struct.new(:first_name, :last_name); end
+                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Don't extend an instance initialized by `Struct.new`. Use a block to customize the struct.
+    RUBY
+
+    expect_correction(<<~RUBY)
+      Person = Struct.new(:first_name, :last_name)
+    RUBY
+  end
+
   it 'registers an offense when extending instance of ::Struct with do ... end' do
     expect_offense(<<~RUBY)
       class Person < ::Struct.new(:first_name, :last_name) do end