* numeric.c (int_pow): fix previous nubu's commit.

	* test/ruby/test_fixnum.rb: new test.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@12698 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Thu Jul  5 16:37:34 2007  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* numeric.c (int_pow): fix previous nubu's commit.
+
+	* test/ruby/test_fixnum.rb: new test.
+
 Thu Jul  5 15:56:06 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* numeric.c (int_pow): even number multiplication never be negative.

numeric.c

@@ -2281,16 +2281,19 @@ int_pow(long x, unsigned long y)
     long z = 1;
 
     if (neg) x = -x;
-    if (y & 1) z = x;
+    if (y & 1)
+	z = x;
+    else
+	neg = 0;
     y &= ~1;
     do {
 	while (y % 2 == 0) {
 	    long x2 = x * x;
 	    if (x2 < x || !POSFIXABLE(x2)) {
 		VALUE v;
 	      bignum:
-		v = rb_big_pow(rb_int2big(neg ? -x : x), LONG2NUM(y));
-		if (z != 1) v = rb_big_mul(rb_int2big(z), v);
+		v = rb_big_pow(rb_int2big(x), LONG2NUM(y));
+		if (z != 1) v = rb_big_mul(rb_int2big(neg ? -z : z), v);
 		return v;
 	    }
 	    x = x2;
@@ -2304,7 +2307,7 @@ int_pow(long x, unsigned long y)
 	    z = xz;
 	}
     } while (--y);
-    if (neg && (y & 1)) z = -z;
+    if (neg) z = -z;
     return LONG2NUM(z);
 }
 

test/ruby/test_fixnum.rb

@@ -0,0 +1,26 @@
+require 'test/unit'
+
+class TestFixnum < Test::Unit::TestCase
+  def setup
+    @verbose = $VERBOSE
+    $VERBOSE = nil
+  end
+
+  def teardown
+    $VERBOSE = @verbose
+  end
+
+  def test_pow
+    [1, 2, 2**64, 2**63*3, 2**64*3].each do |y|
+      [1, 3].each do |x|
+        z1 = x**y
+        z2 = (-x)**y
+        if y % 2 == 1
+          assert_equal(z2, -z1)
+        else
+          assert_equal(z2, z1)
+        end
+      end
+    end
+  end
+end