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

ChangeLog

@@ -1,3 +1,13 @@
+Tue Dec  9 10:16:24 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* 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]
+
 Sun Dec  7 19:36:12 2014  Kazuki Tsujimoto  <kazuki@callcc.net>
 
 	* ext/socket/basicsocket.c, ext/socket/sockssocket.c:

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

test/ruby/test_objectspace.rb

@@ -102,4 +102,11 @@ End
     }
     End
   end
+
+  def test_each_object_recursive_key
+    assert_normal_exit(<<-'end;', '[ruby-core:66742] [Bug #10579]')
+      h = {["foo"]=>nil}
+      p Thread.current[:__recursive_key__]
+    end;
+  end
 end

thread.c

@@ -4696,6 +4696,8 @@ threadptr_recursive_hash_set(rb_thread_t *th, VALUE hash)
     th->local_storage_recursive_hash = hash;
 }
 
+ID rb_frame_last_func(void);
+
 /*
  * Returns the current "recursive list" used to detect recursion.
  * This list is a hash table, unique for the current thread and for
@@ -4707,7 +4709,8 @@ recursive_list_access(void)
 {
     rb_thread_t *th = GET_THREAD();
     VALUE hash = threadptr_recursive_hash(th);
-    VALUE sym = ID2SYM(rb_frame_this_func());
+    ID mid = rb_frame_last_func();
+    VALUE sym = mid ? ID2SYM(mid) : ID2SYM(idNULL);
     VALUE list;
     if (NIL_P(hash) || !RB_TYPE_P(hash, T_HASH)) {
 	hash = ident_hash_new();