tailcall optimization again (#2528)

This is follow up of r67315.

1 files changed, 13 insertions, 0 deletions

diff --git a/test/ruby/test_optimization.rb b/test/ruby/test_optimization.rb
index 6a9e9601f4..0d4f69240e 100644
--- a/test/ruby/test_optimization.rb
+++ b/test/ruby/test_optimization.rb
@@ -451,6 +451,19 @@ class TestRubyOptimization < Test::Unit::TestCase
     }
   end
 
+  def test_tailcall_not_to_grow_stack
+    bug16161 = '[ruby-core:94881]'
+
+    tailcall("#{<<-"begin;"}\n#{<<~"end;"}")
+    begin;
+      def sum(n, s = 0)
+        return s if n < 1
+        sum(n - 1, n + s)
+      end
+    end;
+    assert_equal(0, sum(1_000_000).to_s.size, message(bug16161) {disasm(:fact_helper)})
+  end
+
   class Bug10557
     def [](_)
       block_given?