thread.c: get rid of invalid ID symbol

* eval.c (rb_frame_last_func): return the most recent frame method
  name.
* thread.c (recursive_list_access): use the last method name,
  instead of the current method name which can be unset in some
  cases, not to use a symbol by the invalid ID.
  [ruby-core:66742] [Bug #10579]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48744 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 13 insertions, 0 deletions

diff --git a/eval.c b/eval.c
index 8390c7dc31..dc5af43928 100644
--- a/eval.c
+++ b/eval.c
@@ -1030,6 +1030,19 @@ prev_frame_func(void)
     return frame_func_id(prev_cfp);
 }
 
+ID
+rb_frame_last_func(void)
+{
+    rb_thread_t *th = GET_THREAD();
+    rb_control_frame_t *cfp = th->cfp;
+    ID mid;
+
+    while (!(mid = frame_func_id(cfp)) &&
+	   (cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp),
+	    !RUBY_VM_CONTROL_FRAME_STACK_OVERFLOW_P(th, cfp)));
+    return mid;
+}
+
 /*
  *  call-seq:
  *     append_features(mod)   -> mod