Fix a false positive for Style/HashEachMethods when both arguments …

…are unused.

`Lint/UnusedBlockArgument` should instead say something about this:

changelog/fix_a_false_positive_for_style_hash_each_methods.md

@@ -0,0 +1 @@
+* [#12634](https://github.com/rubocop/rubocop/pull/12634): Fix a false positive for `Style/HashEachMethods` when both arguments are unused. ([@earlopain][])

lib/rubocop/cop/style/hash_each_methods.rb

@@ -56,7 +56,6 @@ class HashEachMethods < Base
           (call $(call _ ${:keys :values}) :each (block_pass (sym _)))
         PATTERN
 
-        # rubocop:disable Metrics/AbcSize
         def on_block(node)
           return unless handleable?(node)
 
@@ -66,12 +65,22 @@ def on_block(node)
 
           return unless (key, value = each_arguments(node))
 
-          if unused_block_arg_exist?(node, value)
+          check_unused_block_args(node, key, value)
+        end
+        alias on_numblock on_block
+
+        # rubocop:disable Metrics/AbcSize
+        def check_unused_block_args(node, key, value)
+          value_unused = unused_block_arg_exist?(node, value)
+          key_unused = unused_block_arg_exist?(node, key)
+          return if value_unused && key_unused
+
+          if value_unused
             message = message('each_key', node.method_name, value.source)
             unused_range = key.source_range.end.join(value.source_range.end)
 
             register_each_args_offense(node, message, 'each_key', unused_range)
-          elsif unused_block_arg_exist?(node, key)
+          elsif key_unused
             message = message('each_value', node.method_name, key.source)
             unused_range = key.source_range.begin.join(value.source_range.begin)
 
@@ -80,8 +89,6 @@ def on_block(node)
         end
         # rubocop:enable Metrics/AbcSize
 
-        alias on_numblock on_block
-
         def on_block_pass(node)
           kv_each_with_block_pass(node.parent) do |target, method|
             register_kv_with_block_pass_offense(node, target, method)

spec/rubocop/cop/style/hash_each_methods_spec.rb

@@ -105,6 +105,10 @@
         expect_no_offenses('foo.each { |*k, v| do_something(*k, v) }')
       end
 
+      it 'does not register an offense when both arguments of `Enumerable#each` are unused' do
+        expect_no_offenses('foo.each { |k, v| do_something }')
+      end
+
       it 'registers an offense when the rest value block argument of `Enumerable#each` method is unused' do
         expect_offense(<<~RUBY)
           foo.each { |k, *v| do_something(*v) }