* numeric.c: fix flodivmod for cornercases [Bug #6044]

  add ruby_float_mod

* insns.def (opt_mod): use ruby_float_mod

* internal.h: declare ruby_float_mod

* test/ruby/test_float.rb: tests for above

* test/ruby/envutil.rb: create helper assert_is_minus_zero

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@35013 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

6 files changed, 48 insertions, 27 deletions

diff --git a/ChangeLog b/ChangeLog
index 1b7c33468b..950d71381d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+Wed Mar 14 15:09:23 2012  Marc-Andre Lafortune  <[email protected]>
+
+	* numeric.c: fix flodivmod for cornercases [Bug #6044]
+	  add ruby_float_mod
+
+	* insns.def (opt_mod): use ruby_float_mod
+
+	* internal.h: declare ruby_float_mod
+
+	* test/ruby/test_float.rb: tests for above
+
+	* test/ruby/envutil.rb: create helper assert_is_minus_zero
+
 Wed Mar 14 10:44:35 2012  Nobuyoshi Nakada  <[email protected]>
 
 	* enumerator.c (lazy_grep_func): should use === instead of =~, as
diff --git a/insns.def b/insns.def
index 4c82df4c33..6404414eec 100644
--- a/insns.def
+++ b/insns.def
@@ -1618,23 +1618,7 @@ opt_mod
 	else if (HEAP_CLASS_OF(recv) == rb_cFloat &&
 		 HEAP_CLASS_OF(obj) == rb_cFloat &&
 		 BASIC_OP_UNREDEFINED_P(BOP_MOD, FLOAT_REDEFINED_OP_FLAG)) {
-	    double x = RFLOAT_VALUE(recv);
-	    double y = RFLOAT_VALUE(obj);
-	    double div, mod;
-
-	    {
-		double z;
-
-		modf(x / y, &z);
-		mod = x - z * y;
-	    }
-
-	    div = (x - mod) / y;
-	    if (y * mod < 0) {
-		mod += y;
-		div -= 1.0;
-	    }
-	    val = DBL2NUM(mod);
+	    val = DBL2NUM(ruby_float_mod(RFLOAT_VALUE(recv), RFLOAT_VALUE(obj)));
 	}
 	else {
 	    goto INSN_LABEL(normal_dispatch);
diff --git a/internal.h b/internal.h
index 64a67e194d..e5818429ea 100644
--- a/internal.h
+++ b/internal.h
@@ -136,6 +136,7 @@ void Init_newline(void);
 /* numeric.c */
 int rb_num_to_uint(VALUE val, unsigned int *ret);
 int ruby_float_step(VALUE from, VALUE to, VALUE step, int excl);
+double ruby_float_mod(double x, double y);
 
 /* object.c */
 VALUE rb_obj_equal(VALUE obj1, VALUE obj2);
diff --git a/numeric.c b/numeric.c
index 3b09fea17b..5eff5ad547 100644
--- a/numeric.c
+++ b/numeric.c
@@ -817,7 +817,9 @@ flodivmod(double x, double y, double *divp, double *modp)
 #ifdef HAVE_FMOD
     mod = fmod(x, y);
 #else
-    {
+    if((x == 0.0) || (isinf(y) && !isinf(x)))
+        mod = x;
+    else {
 	double z;
 
 	modf(x/y, &z);
@@ -836,6 +838,17 @@ flodivmod(double x, double y, double *divp, double *modp)
     if (divp) *divp = div;
 }
 
+/*
+ * Returns the modulo of division of x by y.
+ * An error will be raised if y == 0.
+ */
+
+double ruby_float_mod(double x, double y) {
+    double mod;
+    flodivmod(x, y, 0, &mod);
+    return mod;
+}
+
 
 /*
  *  call-seq:
@@ -851,7 +864,7 @@ flodivmod(double x, double y, double *divp, double *modp)
 static VALUE
 flo_mod(VALUE x, VALUE y)
 {
-    double fy, mod;
+    double fy;
 
     switch (TYPE(y)) {
       case T_FIXNUM:
@@ -866,8 +879,7 @@ flo_mod(VALUE x, VALUE y)
       default:
 	return rb_num_coerce_bin(x, y, '%');
     }
-    flodivmod(RFLOAT_VALUE(x), fy, 0, &mod);
-    return DBL2NUM(mod);
+    return DBL2NUM(ruby_float_mod(RFLOAT_VALUE(x), fy));
 }
 
 static VALUE
@@ -2733,12 +2745,7 @@ fix_mod(VALUE x, VALUE y)
 	x = rb_int2big(FIX2LONG(x));
 	return rb_big_modulo(x, y);
       case T_FLOAT:
-	{
-	    double mod;
-
-	    flodivmod((double)FIX2LONG(x), RFLOAT_VALUE(y), 0, &mod);
-	    return DBL2NUM(mod);
-	}
+	return DBL2NUM(ruby_float_mod((double)FIX2LONG(x), RFLOAT_VALUE(y)));
       default:
 	return rb_num_coerce_bin(x, y, '%');
     }
diff --git a/test/ruby/envutil.rb b/test/ruby/envutil.rb
index 80700d6dc5..3e0c1a3f00 100644
--- a/test/ruby/envutil.rb
+++ b/test/ruby/envutil.rb
@@ -212,6 +212,10 @@ module Test
         assert_equal([true, ""], [status.success?, err], message)
         assert_operator(after.fdiv(before), :<, limit, message)
       end
+
+      def assert_is_minus_zero(f)
+        assert(1.0/f == -Float::INFINITY, "#{f} is not -0.0")
+      end
     end
   end
 end
diff --git a/test/ruby/test_float.rb b/test/ruby/test_float.rb
index 1935cfdd52..f561d00158 100644
--- a/test/ruby/test_float.rb
+++ b/test/ruby/test_float.rb
@@ -195,6 +195,18 @@ class TestFloat < Test::Unit::TestCase
     assert_raise(TypeError) { 2.0.send(:%, nil) }
   end
 
+  def test_modulo3
+    bug6048 = '[ruby-core:42726]'
+    assert_equal(4.2, 4.2.send(:%, Float::INFINITY))
+    assert_equal(4.2, 4.2 % Float::INFINITY)
+    assert_is_minus_zero(-0.0 % 4.2)
+    assert_is_minus_zero(-0.0.send :%, 4.2)
+    assert_raise(ZeroDivisionError) { 4.2.send(:%, 0.0) }
+    assert_raise(ZeroDivisionError) { 4.2 % 0.0 }
+    assert_raise(ZeroDivisionError) { 42.send(:%, 0) }
+    assert_raise(ZeroDivisionError) { 42 % 0 }
+  end
+
   def test_divmod2
     assert_equal([1.0, 0.0], 2.0.divmod(2))
     assert_equal([1.0, 0.0], 2.0.divmod((2**32).coerce(2).first))