Add variadic helper functions for CheckedNumeric math operations

base/numerics/safe_numerics_unittest.cc

Index: base/numerics/safe_numerics_unittest.cc
diff --git a/base/numerics/safe_numerics_unittest.cc b/base/numerics/safe_numerics_unittest.cc
index 430f7700b5d08e4c53d9cb90752e9f2172dd9455..8742002bc011f4f4b4d418cd98471c9ef9a132d5 100644
--- a/base/numerics/safe_numerics_unittest.cc
+++ b/base/numerics/safe_numerics_unittest.cc
@@ -818,3 +818,24 @@ TEST(SafeNumerics, CompoundNumericOperations) {
   too_large /= d;
   EXPECT_FALSE(too_large.IsValid());
 }
+
+TEST(SafeNumerics, VariadicNumericOperations) {
+  auto a = base::CheckedAdd(1, 2UL, 3LL, 4).ValueOrDie();

[Tom Sepez, 2016/11/23 16:52:06]

Can we throw a checked numeric argument into each of these cases?

[jschuh, 2016/11/23 19:18:00]

Sounds good. I was going to add a simple wrapper template function for cases
like this, so might as well do it here.

[jschuh, 2016/11/23 21:49:22]

Done.

+  EXPECT_EQ(static_cast<decltype(a)>(10), a);
+  auto b = base::CheckedSub(20, 2UL, 4).ValueOrDie();
+  EXPECT_EQ(static_cast<decltype(b)>(14.0), b);
+  auto c = base::CheckedMul(20, 1, 5, 3UL).ValueOrDie();
+  EXPECT_EQ(static_cast<decltype(c)>(300.0), c);
+  auto d = base::CheckedDiv(20, 2.0, 5LL, -4).ValueOrDie();
+  EXPECT_EQ(static_cast<decltype(d)>(-.5), d);
+  auto e = base::CheckedMod(20, 3).ValueOrDie();
+  EXPECT_EQ(static_cast<decltype(e)>(2), e);
+  auto f = base::CheckedLsh(1, 2).ValueOrDie();
+  EXPECT_EQ(static_cast<decltype(f)>(4), f);
+  auto g = base::CheckedRsh(4, 2).ValueOrDie();
+  EXPECT_EQ(static_cast<decltype(g)>(1), g);
+  auto h =
+      base::CheckedRsh(base::CheckedAdd(1, 1, 1, 1), base::CheckedSub(4, 2))
+          .ValueOrDie();
+  EXPECT_EQ(static_cast<decltype(h)>(1), h);
+}