Add support for CheckedNumeric bitshift operators

base/numerics/safe_numerics_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <limits>
 #include <type_traits>
 
@@ skipping 17 matching lines @@
 using base::StrictNumeric;
 using base::saturated_cast;
 using base::strict_cast;
 using base::internal::MaxExponent;
 using base::internal::RANGE_VALID;
 using base::internal::RANGE_INVALID;
 using base::internal::RANGE_OVERFLOW;
 using base::internal::RANGE_UNDERFLOW;
 using base::internal::SignedIntegerForSize;
 
-// These tests deliberately cause arithmetic overflows. If the compiler is
-// aggressive enough, it can const fold these overflows. Disable warnings about
-// overflows for const expressions.
+// These tests deliberately cause arithmetic boundary errors. If the compiler is
+// aggressive enough, it can const detect these errors, so we disable warnings.
 #if defined(OS_WIN)
-#pragma warning(disable:4756)
+#pragma warning(disable : 4756)  // Arithmetic overflow.
+#pragma warning(disable : 4293)  // Invalid shift.
 #endif
 
 // This is a helper function for finding the maximum value in Src that can be
 // wholy represented as the destination floating-point type.
 template <typename Dst, typename Src>
 Dst GetMaxConvertibleToFloat() {
   typedef numeric_limits<Dst> DstLimits;
   typedef numeric_limits<Src> SrcLimits;
   static_assert(SrcLimits::is_specialized, "Source must be numeric.");
   static_assert(DstLimits::is_specialized, "Destination must be numeric.");
@@ skipping 63 matching lines @@
   TEST_EXPECTED_VALUE(0, CheckedNumeric<Dst>(DstLimits::min()) % 2);
   TEST_EXPECTED_VALUE(1, CheckedNumeric<Dst>(DstLimits::max()) % 2);
   // Test all the different modulus combinations.
   TEST_EXPECTED_VALUE(0, CheckedNumeric<Dst>(1) % CheckedNumeric<Dst>(1));
   TEST_EXPECTED_VALUE(0, 1 % CheckedNumeric<Dst>(1));
   TEST_EXPECTED_VALUE(0, CheckedNumeric<Dst>(1) % 1);
   CheckedNumeric<Dst> checked_dst = 1;
   TEST_EXPECTED_VALUE(0, checked_dst %= 1);
   // Test that div by 0 is avoided but returns invalid result.
   TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(1) % 0);
+  // Test bit shifts.
+  volatile Dst negative_one = -1;
+  TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(1) << negative_one);
+  TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(1) << (sizeof(Dst) * CHAR_BIT - 1));
+  TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(0) << (sizeof(Dst) * CHAR_BIT));
+  TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(DstLimits::max()) << 1);
+  TEST_EXPECTED_VALUE(static_cast<Dst>(1) << (sizeof(Dst) * CHAR_BIT - 2),
+                      CheckedNumeric<Dst>(1) << (sizeof(Dst) * CHAR_BIT - 2));
+  TEST_EXPECTED_VALUE(0, CheckedNumeric<Dst>(0)
+                             << (sizeof(Dst) * CHAR_BIT - 1));
+  TEST_EXPECTED_VALUE(1, CheckedNumeric<Dst>(1) << 0);
+  TEST_EXPECTED_VALUE(2, CheckedNumeric<Dst>(1) << 1);
+  TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(1) >> (sizeof(Dst) * CHAR_BIT));
+  TEST_EXPECTED_VALUE(0,
+                      CheckedNumeric<Dst>(1) >> (sizeof(Dst) * CHAR_BIT - 1));
+  TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(1) >> negative_one);
 }
 
 // Unsigned integer arithmetic.
 template <typename Dst>
 static void TestSpecializedArithmetic(
     const char* dst,
     int line,
     typename std::enable_if<numeric_limits<Dst>::is_integer &&
                                 !numeric_limits<Dst>::is_signed,
                             int>::type = 0) {
@@ skipping 17 matching lines @@
   TEST_EXPECTED_VALUE(0, CheckedNumeric<Dst>(DstLimits::min()) % 2);
   TEST_EXPECTED_VALUE(1, CheckedNumeric<Dst>(DstLimits::max()) % 2);
   // Test all the different modulus combinations.
   TEST_EXPECTED_VALUE(0, CheckedNumeric<Dst>(1) % CheckedNumeric<Dst>(1));
   TEST_EXPECTED_VALUE(0, 1 % CheckedNumeric<Dst>(1));
   TEST_EXPECTED_VALUE(0, CheckedNumeric<Dst>(1) % 1);
   CheckedNumeric<Dst> checked_dst = 1;
   TEST_EXPECTED_VALUE(0, checked_dst %= 1);
   // Test that div by 0 is avoided but returns invalid result.
   TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(1) % 0);
+  TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(1) << (sizeof(Dst) * CHAR_BIT));
+  // Test bit shifts.
+  volatile int negative_one = -1;
+  TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(1) << negative_one);
+  TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(1) << (sizeof(Dst) * CHAR_BIT));
+  TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(0) << (sizeof(Dst) * CHAR_BIT));
+  TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(DstLimits::max()) << 1);
+  TEST_EXPECTED_VALUE(static_cast<Dst>(1) << (sizeof(Dst) * CHAR_BIT - 1),
+                      CheckedNumeric<Dst>(1) << (sizeof(Dst) * CHAR_BIT - 1));
+  TEST_EXPECTED_VALUE(1, CheckedNumeric<Dst>(1) << 0);
+  TEST_EXPECTED_VALUE(2, CheckedNumeric<Dst>(1) << 1);
+  TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(1) >> (sizeof(Dst) * CHAR_BIT));
+  TEST_EXPECTED_VALUE(0,
+                      CheckedNumeric<Dst>(1) >> (sizeof(Dst) * CHAR_BIT - 1));
+  TEST_EXPECTED_FAILURE(CheckedNumeric<Dst>(1) >> negative_one);
 }
 
 // Floating point arithmetic.
 template <typename Dst>
 void TestSpecializedArithmetic(
     const char* dst,
     int line,
     typename std::enable_if<numeric_limits<Dst>::is_iec559, int>::type = 0) {
   typedef numeric_limits<Dst> DstLimits;
   TEST_EXPECTED_SUCCESS(-CheckedNumeric<Dst>(DstLimits::min()));
@@ skipping 596 matching lines @@
 
   CheckedNumeric<int> too_large = std::numeric_limits<int>::max();
   EXPECT_TRUE(too_large.IsValid());
   too_large += d;
   EXPECT_FALSE(too_large.IsValid());
   too_large -= d;
   EXPECT_FALSE(too_large.IsValid());
   too_large /= d;
   EXPECT_FALSE(too_large.IsValid());
 }