Fix memory leak at the same named alias [Bug #18516]

When aliasing a method to the same name method, set a separate bit
flag on that method definition, instead of the reference count
increment.  Although this kind of alias has no actual effect at
runtime, is used as the hack to suppress the method re-definition
warning.

1 files changed, 18 insertions, 0 deletions

diff --git a/test/ruby/test_alias.rb b/test/ruby/test_alias.rb
index c6fad25cc2..99f2223b49 100644
--- a/test/ruby/test_alias.rb
+++ b/test/ruby/test_alias.rb
@@ -264,4 +264,22 @@ class TestAlias < Test::Unit::TestCase
       end
     end;
   end
+
+  def test_alias_memory_leak
+    assert_no_memory_leak([], "#{<<~"begin;"}", "#{<<~'end;'}", rss: true)
+    begin;
+      class A
+        500.times do
+          1000.times do |i|
+            define_method(:"foo_#{i}") {}
+
+            alias :"foo_#{i}" :"foo_#{i}"
+
+            remove_method :"foo_#{i}"
+          end
+          GC.start
+        end
+      end
+    end;
+  end
 end