[Fix #8990] Make Style/HashEachMethods aware of Thread.current

Fixes #8990.

This PR makes `Style/HashEachMethods` aware of built-in `Thread.current`.
And `Thread.current` is set to `AllowedReceivers` by default that can be
specified for method calls.

changelog/fix_make_style_hash_each_methods_aware_of_thread_current.md

@@ -0,0 +1 @@
+* [#8990](https://github.com/rubocop/rubocop/issues/8990): Make `Style/HashEachMethods` aware of built-in `Thread.current`. ([@koic][])

config/default.yml

@@ -3858,7 +3858,8 @@ Style/HashEachMethods:
   Safe: false
   VersionAdded: '0.80'
   VersionChanged: '1.16'
-  AllowedReceivers: []
+  AllowedReceivers:
+    - Thread.current
 
 Style/HashExcept:
   Description: >-

lib/rubocop/cop/style/hash_each_methods.rb

@@ -118,11 +118,23 @@ def kv_range(outer_node)
         end
 
         def allowed_receiver?(receiver)
-          receiver_name = receiver.send_type? ? receiver.method_name.to_s : receiver.source
+          receiver_name = receiver_name(receiver)
 
           allowed_receivers.include?(receiver_name)
         end
 
+        def receiver_name(receiver)
+          if receiver.send_type?
+            if receiver.receiver
+              "#{receiver_name(receiver.receiver)}.#{receiver.method_name}"
+            else
+              receiver.method_name.to_s
+            end
+          else
+            receiver.source
+          end
+        end
+
         def allowed_receivers
           cop_config.fetch('AllowedReceivers', [])
         end

spec/rubocop/cop/style/hash_each_methods_spec.rb

@@ -186,5 +186,15 @@
         RUBY
       end
     end
+
+    context "when `AllowedReceivers: ['Thread.current']`" do
+      let(:cop_config) { { 'AllowedReceivers' => ['Thread.current'] } }
+
+      it 'does not register an offense when receiver is `Thread.current` method' do
+        expect_no_offenses(<<~RUBY)
+          Thread.current.keys.each { |k| p k }
+        RUBY
+      end
+    end
   end
 end