nobu	2019-03-11 10:37:16 +0900 (Mon, 11 Mar 2019)

  New Revision: 67203

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=67203

  Log:
    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]

  Modified files:
    trunk/ext/-test-/integer/core_ext.c
    trunk/numeric.c
    trunk/test/-ext-/integer/test_integer.rb
Index: test/-ext-/integer/test_integer.rb
===================================================================
--- test/-ext-/integer/test_integer.rb	(revision 67202)
+++ test/-ext-/integer/test_integer.rb	(revision 67203)
@@ -12,4 +12,15 @@ class Test_Integer < Test::Unit::TestCas https://github.com/ruby/ruby/blob/trunk/test/-ext-/integer/test_integer.rb#L12
     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
Index: ext/-test-/integer/core_ext.c
===================================================================
--- ext/-test-/integer/core_ext.c	(revision 67202)
+++ ext/-test-/integer/core_ext.c	(revision 67203)
@@ -20,10 +20,17 @@ rb_int_to_bignum(VALUE x) https://github.com/ruby/ruby/blob/trunk/ext/-test-/integer/core_ext.c#L20
     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);
 }
Index: numeric.c
===================================================================
--- numeric.c	(revision 67202)
+++ numeric.c	(revision 67203)
@@ -3988,6 +3988,7 @@ int_pow(long x, unsigned long y) https://github.com/ruby/ruby/blob/trunk/numeric.c#L3988
     long z = 1;
 
     if (y == 0) return INT2FIX(1);
+    if (y == 1) return LONG2NUM(x);
     if (neg) x = -x;
     if (y & 1)
 	z = x;

--
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