* enumerator.c (enumerator_initialize): Warn when using deprecated form

[Feature #6636]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37495 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

enumerator.c

@@ -357,6 +357,7 @@ enumerator_initialize(int argc, VALUE *argv, VALUE obj)
 	recv = generator_init(generator_allocate(rb_cGenerator), rb_block_proc());
     }
     else {
+	rb_warn("Enumerator.new without a block is deprecated; use Object#to_enum");
 	recv = *argv++;
 	if (--argc) {
 	    meth = *argv++;

test/ruby/test_enumerator.rb

@@ -57,7 +57,10 @@ class TestEnumerator < Test::Unit::TestCase
 
   def test_initialize
     assert_equal([1, 2, 3], @obj.to_enum(:foo, 1, 2, 3).to_a)
-    assert_equal([1, 2, 3], Enumerator.new(@obj, :foo, 1, 2, 3).to_a)
+    _, err = capture_io do
+      assert_equal([1, 2, 3], Enumerator.new(@obj, :foo, 1, 2, 3).to_a)
+    end
+    assert_match 'Enumerator.new without a block is deprecated', err
     assert_equal([1, 2, 3], Enumerator.new { |y| i = 0; loop { y << (i += 1) } }.take(3))
     assert_raise(ArgumentError) { Enumerator.new }
   end