[Fix #11663] Fix an incorrect autocorrect for Style/BlockDelimiters

Fixes #11663.

This PR fixes an incorrect autocorrect for `Style/BlockDelimiters`
when multi-line blocks to `{` and `}` with arithmetic operation method chain.

changelog/fix_an_incorrect_autocorrect_for_style_block_delimiters.md

@@ -0,0 +1 @@
+* [#11663](https://github.com/rubocop/rubocop/issues/11663): Fix an incorrect autocorrect for `Style/BlockDelimiters` when multi-line blocks to `{` and `}` with arithmetic operation method chain. ([@koic][])

lib/rubocop/cop/style/block_delimiters.rb

@@ -342,6 +342,7 @@ def get_blocks(node, &block)
         end
 
         def proper_block_style?(node)
+          return true if require_braces?(node)
           return special_method_proper_block_style?(node) if special_method?(node.method_name)
 
           case style
@@ -352,6 +353,14 @@ def proper_block_style?(node)
           end
         end
 
+        def require_braces?(node)
+          return false unless node.braces?
+
+          node.each_ancestor(:send).any? do |send|
+            send.arithmetic_operation? && node.source_range.end_pos < send.loc.selector.begin_pos
+          end
+        end
+
         def special_method?(method_name)
           allowed_method?(method_name) ||
             matches_allowed_pattern?(method_name) ||

spec/rubocop/cop/style/block_delimiters_spec.rb

@@ -603,6 +603,26 @@
         RUBY
       end
 
+      it 'registers an offense and autocorrects when multi-line blocks to `{` and `}` with method chain' do
+        expect_offense(<<~RUBY)
+          foo bar + baz {
+                        ^ Avoid using `{...}` for multi-line blocks.
+          }.qux.quux
+        RUBY
+
+        expect_correction(<<~RUBY)
+          foo bar + baz do
+          end.qux.quux
+        RUBY
+      end
+
+      it 'does not register an offense when multi-line blocks to `{` and `}` with arithmetic operation method chain' do
+        expect_no_offenses(<<~RUBY)
+          foo bar + baz {
+          }.qux + quux
+        RUBY
+      end
+
       it 'does not autocorrect {} if do-end would introduce a syntax error' do
         expect_no_offenses(<<~RUBY)
           my_method :arg1, arg2: proc {