Fix WithScope for destructured post arguments

Author: vinistock

lib/syntax_tree/node.rb

@@ -8277,8 +8277,8 @@ def format(q)
     # parameter
     attr_reader :rest
 
-    # [Array[ Ident ]] any positional parameters that exist after a rest
-    # parameter
+    # [Array[ Ident | MLHSParen ]] any positional parameters that exist after a
+    #  rest parameter
     attr_reader :posts
 
     # [Array[ [ Label, nil | Node ] ]] any keyword parameters and their

lib/syntax_tree/with_scope.rb

@@ -154,7 +154,13 @@ def visit_params(node)
       add_argument_definitions(node.requireds)
 
       node.posts.each do |param|
-        current_scope.add_local_definition(param, :argument)
+        if param.is_a?(SyntaxTree::MLHSParen)
+          param.contents.parts.each do |part|
+            current_scope.add_local_definition(part, :argument)
+          end
+        else
+          current_scope.add_local_definition(param, :argument)
+        end
       end
 
       node.keywords.each do |param|

test/with_scope_test.rb

@@ -154,6 +154,18 @@ def foo(a)
       assert_argument(collector, "a", definitions: [1], usages: [2])
     end
 
+    def test_collecting_methods_with_destructured_post_arguments
+      collector = Collector.collect(<<~RUBY)
+        def foo(optional = 1, (bin, bag))
+        end
+      RUBY
+
+      assert_equal(3, collector.arguments.length)
+      assert_argument(collector, "optional", definitions: [1], usages: [])
+      assert_argument(collector, "bin", definitions: [1], usages: [])
+      assert_argument(collector, "bag", definitions: [1], usages: [])
+    end
+
     def test_collecting_singleton_method_arguments
       collector = Collector.collect(<<~RUBY)
         def self.foo(a)