Support private_class_method in the indexer (#2858)

* Support `private_class_method` in the indexer

Fixes #2781

* Apply suggestions from code review

Co-authored-by: Andy Waite <[email protected]>

* Fix tests

* Remove unnecessary conditional

* Support `private_class_method` being called with a method definition

---------

Co-authored-by: Andy Waite <[email protected]>

lib/ruby_indexer/lib/ruby_indexer/declaration_listener.rb

@@ -282,6 +282,9 @@ def on_call_node_enter(node)
         @visibility_stack.push(Entry::Visibility::PRIVATE)
       when :module_function
         handle_module_function(node)
+      when :private_class_method
+        @visibility_stack.push(Entry::Visibility::PRIVATE)
+        handle_private_class_method(node)
       end
 
       @enhancements.each do |enhancement|
@@ -297,7 +300,7 @@ def on_call_node_enter(node)
     def on_call_node_leave(node)
       message = node.name
       case message
-      when :public, :protected, :private
+      when :public, :protected, :private, :private_class_method
         # We want to restore the visibility stack when we leave a method definition with a visibility modifier
         # e.g. `private def foo; end`
         if node.arguments&.arguments&.first&.is_a?(Prism::DefNode)
@@ -875,6 +878,45 @@ def handle_module_function(node)
       end
     end
 
+    sig { params(node: Prism::CallNode).void }
+    def handle_private_class_method(node)
+      node.arguments&.arguments&.each do |argument|
+        string_or_symbol_nodes = case argument
+        when Prism::StringNode, Prism::SymbolNode
+          [argument]
+        when Prism::ArrayNode
+          argument.elements
+        else
+          []
+        end
+
+        unless string_or_symbol_nodes.empty?
+          # pop the visibility off since there isn't a method definition following `private_class_method`
+          @visibility_stack.pop
+        end
+
+        string_or_symbol_nodes.each do |string_or_symbol_node|
+          method_name = case string_or_symbol_node
+          when Prism::StringNode
+            string_or_symbol_node.content
+          when Prism::SymbolNode
+            string_or_symbol_node.value
+          end
+          next unless method_name
+
+          owner_name = @owner_stack.last&.name
+          next unless owner_name
+
+          entries = @index.resolve_method(method_name, @index.existing_or_new_singleton_class(owner_name).name)
+          next unless entries
+
+          entries.each do |entry|
+            entry.visibility = Entry::Visibility::PRIVATE
+          end
+        end
+      end
+    end
+
     sig { returns(Entry::Visibility) }
     def current_visibility
       T.must(@visibility_stack.last)

lib/ruby_indexer/test/method_test.rb

@@ -149,6 +149,86 @@ def bar; end
       end
     end
 
+    def test_private_class_method_visibility_tracking_string_symbol_arguments
+      index(<<~RUBY)
+        class Test
+          def self.foo
+          end
+
+          def self.bar
+          end
+
+          private_class_method("foo", :bar)
+
+          def self.baz
+          end
+        end
+      RUBY
+
+      ["foo", "bar"].each do |keyword|
+        entries = T.must(@index[keyword])
+        assert_equal(1, entries.size)
+        entry = entries.first
+        assert_predicate(entry, :private?)
+      end
+
+      entries = T.must(@index["baz"])
+      assert_equal(1, entries.size)
+      entry = entries.first
+      assert_predicate(entry, :public?)
+    end
+
+    def test_private_class_method_visibility_tracking_array_argument
+      index(<<~RUBY)
+        class Test
+          def self.foo
+          end
+
+          def self.bar
+          end
+
+          private_class_method(["foo", :bar])
+
+          def self.baz
+          end
+        end
+      RUBY
+
+      ["foo", "bar"].each do |keyword|
+        entries = T.must(@index[keyword])
+        assert_equal(1, entries.size)
+        entry = entries.first
+        assert_predicate(entry, :private?)
+      end
+
+      entries = T.must(@index["baz"])
+      assert_equal(1, entries.size)
+      entry = entries.first
+      assert_predicate(entry, :public?)
+    end
+
+    def test_private_class_method_visibility_tracking_method_argument
+      index(<<~RUBY)
+        class Test
+          private_class_method def self.foo
+          end
+
+          def self.bar
+          end
+        end
+      RUBY
+
+      entries = T.must(@index["foo"])
+      assert_equal(1, entries.size)
+      entry = entries.first
+      assert_predicate(entry, :private?)
+
+      entries = T.must(@index["bar"])
+      assert_equal(1, entries.size)
+      entry = entries.first
+      assert_predicate(entry, :public?)
+    end
+
     def test_comments_documentation
       index(<<~RUBY)
         # Documentation for Foo