bigdecimal.c: fix FloatDomainError

* ext/bigdecimal/bigdecimal.c (GetVpValueWithPrec): consider
  non-finite float values not to raise FloatDomainError.
  [ruby-core:75682] [Bug #12414]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55123 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Mon May 23 12:30:29 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/bigdecimal/bigdecimal.c (GetVpValueWithPrec): consider
+	  non-finite float values not to raise FloatDomainError.
+	  [ruby-core:75682] [Bug #12414]
+
 Mon May 23 12:21:18 2016  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* array.c (rb_ary_fill): suppress warnings: 'item' may be used

ext/bigdecimal/bigdecimal.c

@@ -239,6 +239,12 @@ again:
 	if (prec < 0) goto unable_to_coerce_without_prec;
 	if (prec > DBL_DIG+1) goto SomeOneMayDoIt;
 	d = RFLOAT_VALUE(v);
+	if (!isfinite(d)) {
+	    pv = VpCreateRbObject(prec, NULL);
+	    pv->sign = isnan(d) ? VP_SIGN_NaN :
+		d > 0 ? VP_SIGN_POSITIVE_INFINITE : VP_SIGN_NEGATIVE_FINITE;
+	    return pv;
+	}
 	if (d != 0.0) {
 	    v = rb_funcall(v, id_to_r, 0);
 	    goto again;

test/bigdecimal/test_bigdecimal.rb

@@ -459,6 +459,18 @@ class TestBigDecimal < Test::Unit::TestCase
     assert_equal(false, BigDecimal.new("NaN") > n1)
   end
 
+  def test_cmp_float_nan
+    assert_equal(nil, BigDecimal.new("1") <=> Float::NAN)
+  end
+
+  def test_cmp_float_pos_inf
+    assert_equal(-1, BigDecimal.new("1") <=> Float::INFINITY)
+  end
+
+  def test_cmp_float_neg_inf
+    assert_equal(+1, BigDecimal.new("1") <=> -Float::INFINITY)
+  end
+
   def test_cmp_failing_coercion
     n1 = BigDecimal.new("1")
     assert_equal(nil, n1 <=> nil)