From 384839234d2374ac4e81aef8cf8e02dc675ec398 Mon Sep 17 00:00:00 2001
From: Marc-Andre Lafortune <github@marc-andre.ca>
Date: Tue, 4 Aug 2020 13:27:26 -0400
Subject: [PATCH] Always freeze `#arguments`

---
 CHANGELOG.md                                     | 1 +
 lib/rubocop/ast/node/block_node.rb               | 2 +-
 lib/rubocop/ast/node/mixin/parameterized_node.rb | 4 ++--
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a8ad0a9aa..72ae002bf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@
 ### Changes
 
 * [#94](https://github.com/rubocop-hq/rubocop-ast/pull/94): In Ruby 2.4, `Set#===` is harmonized with Ruby 2.5+ to call `include?`. ([@marcandre][])
+* [#91](https://github.com/rubocop-hq/rubocop-ast/pull/91): **(Potentially breaking)** `Node#arguments` always returns a frozen array ([@marcandre][])
 
 ## 0.3.0 (2020-08-01)
 
diff --git a/lib/rubocop/ast/node/block_node.rb b/lib/rubocop/ast/node/block_node.rb
index 1af323acd..20b9c3f96 100644
--- a/lib/rubocop/ast/node/block_node.rb
+++ b/lib/rubocop/ast/node/block_node.rb
@@ -25,7 +25,7 @@ def send_node
       # @return [Array<Node>]
       def arguments
         if numblock_type?
-          [] # Numbered parameters have no block arguments.
+          [].freeze # Numbered parameters have no block arguments.
         else
           node_parts[1]
         end
diff --git a/lib/rubocop/ast/node/mixin/parameterized_node.rb b/lib/rubocop/ast/node/mixin/parameterized_node.rb
index 0a08cfa34..e1fe069cc 100644
--- a/lib/rubocop/ast/node/mixin/parameterized_node.rb
+++ b/lib/rubocop/ast/node/mixin/parameterized_node.rb
@@ -82,9 +82,9 @@ def arguments
       # and optimizes other calls
       module RestArguments
         include ParameterizedNode
-        # @return [Array] arguments, if any
+        # @return [Array<Node>] arguments, if any
         def arguments
-          children[first_argument_index..-1]
+          children[first_argument_index..-1].freeze
         end
 
         # A shorthand for getting the first argument of the node.