Revert r42942; a revert requires a reason

* rational.c (nurat_div): reverted r28844, r28886 and r28887.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42952 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 12 insertions, 1 deletions

diff --git a/rational.c b/rational.c
index 53bc11c4ef..a572dceb11 100644
--- a/rational.c
+++ b/rational.c
@@ -950,8 +950,19 @@ nurat_div(VALUE self, VALUE other)
 			    other, ONE, '/');
 	}
     }
-    else if (RB_TYPE_P(other, T_FLOAT))
+    else if (RB_TYPE_P(other, T_FLOAT)) {
+	{
+	    double x = RFLOAT_VALUE(other), den;
+	    get_dat1(self);
+
+	    if (isnan(x)) return DBL2NUM(NAN);
+	    if (isinf(x)) return INT2FIX(0);
+	    if (x != 0.0 && modf(x, &den) == 0.0) {
+		return rb_rational_raw2(dat->num, f_mul(rb_dbl2big(den), dat->den));
+	    }
+	}
 	return rb_funcall(f_to_f(self), '/', 1, other);
+    }
     else if (RB_TYPE_P(other, T_RATIONAL)) {
 	if (f_zero_p(other))
 	    rb_raise_zerodiv();