commit 36f113885eed8c58f5008399b297049b68bc4c53
Author: Akinori MUSHA <knu@idaemons.org>
Date:   Tue Sep 1 14:48:33 2015 +0900

    * vm_eval.c (rb_f_loop): When a loop is stopped by a StopIteration
      exception, return what the enumerator has returned instead of
      nil.

diff --git a/ChangeLog b/ChangeLog
index 77779a5..d8af4f2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Tue Sep  1 14:49:27 2015  Akinori MUSHA  <knu@iDaemons.org>
+
+	* vm_eval.c (rb_f_loop): When a loop is stopped by a StopIteration
+	  exception, return what the enumerator has returned instead of
+	  nil.
+
 Mon Aug 31 17:04:45 2015  Koichi Sasada  <ko1@atdot.net>
 
 	* class.c (move_refined_method): should insert a write barrier
diff --git a/NEWS b/NEWS
index 1803ed9..f29358c 100644
--- a/NEWS
+++ b/NEWS
@@ -44,6 +44,11 @@ with all sufficient information, see the ChangeLog file.
     this parameter is bitwise-ORed to oflags generated by normal mode argument.
     [Feature #11253]
 
+* Kernel
+
+  * Kernel#loop, when stopped by a StopIteration exception, returns
+    what the enumerator has returned instead of nil.
+
 * Module
   * Module#deprecate_constant [Feature #11398]
 
diff --git a/test/ruby/test_enumerator.rb b/test/ruby/test_enumerator.rb
index b5ced3b..85e8c48 100644
--- a/test/ruby/test_enumerator.rb
+++ b/test/ruby/test_enumerator.rb
@@ -46,6 +46,14 @@ class TestEnumerator < Test::Unit::TestCase
     }
   end
 
+  def test_loop_return_value
+    assert_equal nil, loop { break }
+    assert_equal 42,  loop { break 42 }
+
+    e = Enumerator.new { |y| y << 1; y << 2; :stopped }
+    assert_equal :stopped, loop { e.next while true }
+  end
+
   def test_nested_iteration
     def (o = Object.new).each
       yield :ok1
diff --git a/vm_eval.c b/vm_eval.c
index 00b47e5..a08e211 100644
--- a/vm_eval.c
+++ b/vm_eval.c
@@ -24,7 +24,7 @@ static void vm_set_eval_stack(rb_thread_t * th, const rb_iseq_t *iseq, const rb_
 static int vm_collect_local_variables_in_heap(rb_thread_t *th, const VALUE *dfp, const struct local_var_list *vars);
 
 static VALUE rb_eUncaughtThrow;
-static ID id_tag, id_value;
+static ID id_result, id_tag, id_value;
 #define id_mesg idMesg
 
 /* vm_backtrace.c */
@@ -1067,6 +1067,12 @@ loop_i(void)
 }
 
 static VALUE
+loop_stop(VALUE dummy, VALUE exc)
+{
+    return rb_attr_get(exc, id_result);
+}
+
+static VALUE
 rb_f_loop_size(VALUE self, VALUE args, VALUE eobj)
 {
     return DBL2NUM(INFINITY);
@@ -1095,8 +1101,7 @@ static VALUE
 rb_f_loop(VALUE self)
 {
     RETURN_SIZED_ENUMERATOR(self, 0, 0, rb_f_loop_size);
-    rb_rescue2(loop_i, (VALUE)0, 0, 0, rb_eStopIteration, (VALUE)0);
-    return Qnil;		/* dummy */
+    return rb_rescue2(loop_i, (VALUE)0, loop_stop, (VALUE)0, rb_eStopIteration, (VALUE)0);
 }
 
 #if VMDEBUG
@@ -2172,6 +2177,7 @@ Init_vm_eval(void)
     rb_define_method(rb_eUncaughtThrow, "value", uncaught_throw_value, 0);
     rb_define_method(rb_eUncaughtThrow, "to_s", uncaught_throw_to_s, 0);
 
+    id_result = rb_intern_const("result");
     id_tag = rb_intern_const("tag");
     id_value = rb_intern_const("value");
 }