[Fix rubocop#12807] Fix false positives for Naming/BlockForwarding

Fixes rubocop#12807.

This PR fixes false positives for `Naming/BlockForwarding`
when using explicit block forwarding in block method and others.

changelog/fix_false_positives_for_naming_block_forwarding.md

@@ -0,0 +1 @@
+* [#12807](https://github.com/rubocop/rubocop/issues/12807): Fix false positives for `Naming/BlockForwarding` when using explicit block forwarding in block method and others. ([@koic][])

lib/rubocop/cop/naming/block_forwarding.rb

@@ -51,29 +51,25 @@ def self.autocorrect_incompatible_with
           [Lint::AmbiguousOperator, Style::ArgumentsForwarding]
         end
 
-        # rubocop:disable Metrics/CyclomaticComplexity
         def on_def(node)
           return if node.arguments.empty?
 
           last_argument = node.last_argument
           return if expected_block_forwarding_style?(node, last_argument)
 
-          invalid_syntax = false
-          node.each_descendant(:block_pass) do |block_pass_node|
-            next if block_pass_node.children.first&.sym_type? ||
-                    last_argument.source != block_pass_node.source
+          forwarded_args = node.each_descendant(:block_pass).with_object([]) do |block_pass, result|
+            return nil if invalid_syntax?(block_pass)
+            next unless block_argument_name_matched?(block_pass, last_argument)
 
-            if block_pass_node.each_ancestor(:block, :numblock).any?
-              invalid_syntax = true
-              next
-            end
+            result << block_pass
+          end
 
-            register_offense(block_pass_node, node)
+          forwarded_args.each do |forwarded_arg|
+            register_offense(forwarded_arg, node)
           end
 
-          register_offense(last_argument, node) unless invalid_syntax
+          register_offense(last_argument, node)
         end
-        # rubocop:enable Metrics/CyclomaticComplexity
         alias on_defs on_def
 
         private
@@ -88,6 +84,29 @@ def expected_block_forwarding_style?(node, last_argument)
           end
         end
 
+        def block_argument_name_matched?(block_pass_node, last_argument)
+          return false if block_pass_node.children.first&.sym_type?
+
+          last_argument.source == block_pass_node.source
+        end
+
+        # Prevents the following syntax error:
+        #
+        # # foo.rb
+        # def foo(&)
+        #   block_method do
+        #     bar(&)
+        #   end
+        # end
+        #
+        # $ ruby -vc foo.rb
+        # ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [x86_64-darwin22]
+        # foo.rb: foo.rb:4: anonymous block parameter is also used within block (SyntaxError)
+        #
+        def invalid_syntax?(block_pass_node)
+          block_pass_node.each_ancestor(:block, :numblock).any?
+        end
+
         def use_kwarg_in_method_definition?(node)
           node.arguments.each_descendant(:kwarg, :kwoptarg).any?
         end

spec/rubocop/cop/naming/block_forwarding_spec.rb

@@ -230,6 +230,54 @@ def foo(&block)
         RUBY
       end
 
+      it 'does not register an offense when using explicit block forwarding in block method and after' do
+        # Prevents the following syntax error:
+        #
+        # # foo.rb
+        # def foo(&)
+        #   block_method do
+        #     bar(&)
+        #   end
+        # end
+        #
+        # $ ruby -vc foo.rb
+        # ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [x86_64-darwin22]
+        # foo.rb: foo.rb:4: anonymous block parameter is also used within block (SyntaxError)
+        #
+        expect_no_offenses(<<~RUBY)
+          def foo(&block)
+            block_method do
+              bar(&block)
+            end
+            baz(&block)
+          end
+        RUBY
+      end
+
+      it 'does not register an offense when using explicit block forwarding in block method and before' do
+        # Prevents the following syntax error:
+        #
+        # # foo.rb
+        # def foo(&)
+        #   block_method do
+        #     bar(&)
+        #   end
+        # end
+        #
+        # $ ruby -vc foo.rb
+        # ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [x86_64-darwin22]
+        # foo.rb: foo.rb:4: anonymous block parameter is also used within block (SyntaxError)
+        #
+        expect_no_offenses(<<~RUBY)
+          def foo(&block)
+            bar(&block)
+            block_method do
+              baz(&block)
+            end
+          end
+        RUBY
+      end
+
       it 'does not register an offense when defining no arguments method' do
         expect_no_offenses(<<~RUBY)
           def foo