parse.y: pin down dynamic symbol only

* parse.y (rb_id_attrset): pin down dynamic symbol only. it is
  possibe that attrset ID can be registered as a static symbol
  after the corresponding attrget ID has been registered as a
  dynamic, and then the latter may be collected.
  [ruby-core:62226] [Bug #9787]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45756 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 18 insertions, 0 deletions

diff --git a/test/ruby/test_symbol.rb b/test/ruby/test_symbol.rb
index 686b74d1e7..e74c41cd2d 100644
--- a/test/ruby/test_symbol.rb
+++ b/test/ruby/test_symbol.rb
@@ -237,4 +237,22 @@ class TestSymbol < Test::Unit::TestCase
                        '',
                        child_env: '--disable-gems')
   end
+
+  def test_gc_attrset
+    bug9787 = '[ruby-core:62226] [Bug #9787]'
+    assert_normal_exit(<<-'end;', '', child_env: '--disable-gems')
+      def noninterned_name(prefix = "")
+        prefix += "_#{Thread.current.object_id.to_s(36).tr('-', '_')}"
+        begin
+          name = "#{prefix}_#{rand(0x1000).to_s(16)}_#{Time.now.usec}"
+        end while Symbol.find(name) or Symbol.find(name + "=")
+        name
+      end
+      n = noninterned_name("gc")
+      n.to_sym
+      GC.start(immediate_sweep: false)
+      eval(":#{n}=")
+      eval("proc{self.#{n} = nil}")
+    end;
+  end
 end