Mark cc->cme_ for refinement callcaches as well

This is required for the same reason that super CC needs it.
See 36023d5cb751d62fca0c27901c07527b20170f4d.

Reproducer:

    def cached_foo_callsite(obj) = obj.foo

    class Foo
      def foo = :v1

      module R
        refine Foo do
          def foo = :unused
        end
      end
    end

    obj = Foo.new
    cached_foo_callsite(obj) # set up cc with cme for foo=:v1

    class Foo
      def foo = :v2
    end
    GC.start # cme for foo=:v1 collected, if not reachable by cached_foo_callsite

    cached_foo_callsite(obj)

[Bug #19994]

1 files changed, 4 insertions, 3 deletions

diff --git a/gc.c b/gc.c
index d1c5efb780..260b891b1e 100644
--- a/gc.c
+++ b/gc.c
@@ -7216,12 +7216,13 @@ gc_mark_imemo(rb_objspace_t *objspace, VALUE obj)
          * - On the multi-Ractors, cme will be collected with global GC
          *   so that it is safe if GC is not interleaving while accessing
          *   cc and cme.
-         * - However, cc_type_super is not chained from cc so the cc->cme
-         *   should be marked.
+         * - However, cc_type_super and cc_type_refinement are not chained
+         *   from ccs so cc->cme should be marked; the cme might be
+         *   reachable only through cc in these cases.
          */
         {
             const struct rb_callcache *cc = (const struct rb_callcache *)obj;
-            if (vm_cc_super_p(cc)) {
+            if (vm_cc_super_p(cc) || vm_cc_refinement_p(cc)) {
                 gc_mark(objspace, (VALUE)cc->cme_);
             }
         }