fix_7452_for_trunk.diff

diff --git a/gc.c b/gc.c
index 63869a0..a698792 100644
--- a/gc.c
+++ b/gc.c
@@ -1499,11 +1499,16 @@ rb_objspace_call_finalizer(rb_objspace_t *objspace)
     RVALUE *p, *pend;
     RVALUE *final_list = 0;
     size_t i;
+    rb_thread_t *th = GET_THREAD();
 
     rest_sweep(objspace);
 
     if (ATOMIC_EXCHANGE(finalizing, 1)) return;
 
+    /* avoid unforced finalizing reachable objects from VM */
+    /* The VM destructor needs these objects. */
+    th->vm->self ? rb_gc_mark(th->vm->self) : rb_vm_mark(th->vm);
+
     /* run finalizers */
     do {
 	finalize_deferred(objspace);
diff --git a/test/ruby/test_gc.rb b/test/ruby/test_gc.rb
index 9d68c1a..11d2b4c 100644
--- a/test/ruby/test_gc.rb
+++ b/test/ruby/test_gc.rb
@@ -134,4 +134,10 @@ class TestGc < Test::Unit::TestCase
   ensure
     GC::Profiler.disable
   end
+
+  def test_finalizing_main_thread
+    assert_in_out_err(%w[--disable-gems], <<-EOS, ["\"finalize\""], [], "[ruby-dev:46647]")
+      ObjectSpace.define_finalizer(Thread.main) { p 'finalize' }
+    EOS
+  end
 end