numeric.c: fix infinite loop

* numeric.c (int_pow): fix infinite loop in the case of y equal 1
  and power of x does not overflow.
  [ruby-core:91734] [Bug #15651]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67203 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 19 insertions, 0 deletions

diff --git a/ext/-test-/integer/core_ext.c b/ext/-test-/integer/core_ext.c
index 6d64cdb0c2..510ba4a1e6 100644
--- a/ext/-test-/integer/core_ext.c
+++ b/ext/-test-/integer/core_ext.c
@@ -20,10 +20,17 @@ rb_int_to_bignum(VALUE x)
     return x;
 }
 
+static VALUE
+positive_pow(VALUE x, VALUE y)
+{
+    return rb_int_positive_pow(NUM2LONG(x), NUM2ULONG(y));
+}
+
 void
 Init_core_ext(VALUE klass)
 {
     rb_define_method(rb_cInteger, "bignum?", int_bignum_p, 0);
     rb_define_method(rb_cInteger, "fixnum?", int_fixnum_p, 0);
     rb_define_method(rb_cInteger, "to_bignum", rb_int_to_bignum, 0);
+    rb_define_method(rb_cInteger, "positive_pow", positive_pow, 1);
 }
diff --git a/numeric.c b/numeric.c
index a1090ff85d..4af829742a 100644
--- a/numeric.c
+++ b/numeric.c
@@ -3988,6 +3988,7 @@ int_pow(long x, unsigned long y)
     long z = 1;
 
     if (y == 0) return INT2FIX(1);
+    if (y == 1) return LONG2NUM(x);
     if (neg) x = -x;
     if (y & 1)
 	z = x;
diff --git a/test/-ext-/integer/test_integer.rb b/test/-ext-/integer/test_integer.rb
index cdabb5403b..8d7785047b 100644
--- a/test/-ext-/integer/test_integer.rb
+++ b/test/-ext-/integer/test_integer.rb
@@ -12,4 +12,15 @@ class Test_Integer < Test::Unit::TestCase
     assert_fixnum(FIXNUM_MAX)
     assert_bignum(FIXNUM_MAX+1)
   end
+
+  def test_positive_pow
+    assert_separately(%w[-r-test-/integer], "#{<<~"begin;"}\n#{<<~'end;'}", timeout: 3)
+    begin;
+      assert_equal(1, 1.positive_pow(1))
+      assert_equal(0, 0.positive_pow(1))
+      assert_equal(3, 3.positive_pow(1))
+      assert_equal(-3, -3.positive_pow(1))
+      assert_equal(9, -3.positive_pow(2))
+    end;
+  end
 end