From 207788466eedfdefcf09fdc5c6217547b5ce4ed1 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Wed, 10 Apr 2024 22:44:33 +0900
Subject: [PATCH] [Bug #20417] Block local variables do not need to warn about
 unused

---
 parse.y               | 4 ++++
 test/ruby/test_ast.rb | 6 ++++++
 2 files changed, 10 insertions(+)

diff --git a/parse.y b/parse.y
index f31a3ed55ec652..8e1a6e4a46d071 100644
--- a/parse.y
+++ b/parse.y
@@ -13814,6 +13814,10 @@ new_bv(struct parser_params *p, ID name)
     }
     if (!shadowing_lvar_0(p, name)) return;
     dyna_var(p, name);
+    ID *vidp = 0;
+    if (dvar_defined_ref(p, name, &vidp)) {
+        if (vidp) *vidp |= LVAR_USED;
+    }
 }
 
 static void
diff --git a/test/ruby/test_ast.rb b/test/ruby/test_ast.rb
index 90d19c3d68eb74..29da607fc5daa1 100644
--- a/test/ruby/test_ast.rb
+++ b/test/ruby/test_ast.rb
@@ -1232,6 +1232,12 @@ def test_with_bom
     EXP
   end
 
+  def test_unused_block_local_variable
+    assert_warning('') do
+      RubyVM::AbstractSyntaxTree.parse(%{->(; foo) {}})
+    end
+  end
+
   def assert_error_tolerant(src, expected, keep_tokens: false)
     begin
       verbose_bak, $VERBOSE = $VERBOSE, false