enumerator.c: fix for non-integral argument for ArithmeticSequence#last

This fixes a bug of Enumerator::ArithmeticSequence#last in the case that
a non-integral argument is passed.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64262 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

enumerator.c

@@ -2495,6 +2495,9 @@ arith_seq_last(int argc, VALUE *argv, VALUE self)
     }
 
     rb_scan_args(argc, argv, "1", &nv);
+    if (!RB_INTEGER_TYPE_P(nv)) {
+        nv = rb_to_int(nv);
+    }
     if (RTEST(rb_int_gt(nv, len))) {
         nv = len;
     }

test/ruby/test_arithmetic_sequence.rb

@@ -195,6 +195,30 @@ class TestArithmeticSequence < Test::Unit::TestCase
     assert_equal([2.0, 0.0, -2.0], seq.last(3))
   end
 
+  def test_last_with_float
+    res = (1..3).step(2).last(2.0)
+    assert_equal([1, 3], res)
+    assert_instance_of Integer, res[0]
+    assert_instance_of Integer, res[1]
+
+    res = (1..3).step(2).last(5.0)
+    assert_equal([1, 3], res)
+    assert_instance_of Integer, res[0]
+    assert_instance_of Integer, res[1]
+  end
+
+  def test_last_with_rational
+    res = (1..3).step(2).last(2r)
+    assert_equal([1, 3], res)
+    assert_instance_of Integer, res[0]
+    assert_instance_of Integer, res[1]
+
+    res = (1..3).step(2).last(10/2r)
+    assert_equal([1, 3], res)
+    assert_instance_of Integer, res[0]
+    assert_instance_of Integer, res[1]
+  end
+
   def test_to_a
     assert_equal([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 1.step(10).to_a)
     assert_equal([1, 3, 5, 7, 9], 1.step(10, 2).to_a)