Fix ubsan warning in byteio_unittest

webrtc/modules/rtp_rtcp/source/byte_io_unittest.cc

Index: webrtc/modules/rtp_rtcp/source/byte_io_unittest.cc
diff --git a/webrtc/modules/rtp_rtcp/source/byte_io_unittest.cc b/webrtc/modules/rtp_rtcp/source/byte_io_unittest.cc
index fbc6bf8469f3c7c3d26b1988da4df4c9bae6c0ed..80a6800258c9002636cd73b1e29c2f8dfcc859f8 100644
--- a/webrtc/modules/rtp_rtcp/source/byte_io_unittest.cc
+++ b/webrtc/modules/rtp_rtcp/source/byte_io_unittest.cc
@@ -31,7 +31,12 @@ class ByteIoTest : public ::testing::Test {
       val = (val << 8) + (negative ? (0xFF - i) : (i + 1));
     }
     if (negative && std::numeric_limits<T>::is_signed) {
-      val |= static_cast<T>(-1) << (8 * num_bytes);
+      T mask = static_cast<T>(-1);
+      const T neg_byte = static_cast<T>(0xFF);
+      for (int i = 0; i < num_bytes; ++i) {
+        mask &= ~(neg_byte << i);
+      }

[stefan-webrtc, 2016/02/26 09:30:34]

Add a comment about what the mask you are constructing looks like.

[sprang_webrtc, 2016/02/26 10:08:25]

Done.

+      val |= mask;
     }
     return val;
   }
@@ -140,26 +145,14 @@ TEST_F(ByteIoTest, Test24SBitBigEndian) {
   TestWrite<int32_t, ByteWriter<int32_t, 3>::WriteBigEndian, 3>(true);
 }
 
-// Disabled for UBSan: https://bugs.chromium.org/p/webrtc/issues/detail?id=5490
-#ifdef UNDEFINED_SANITIZER
-#define MAYBE_Test32SBitBigEndian DISABLED_Test32SBitBigEndian
-#else
-#define MAYBE_Test32SBitBigEndian Test32SBitBigEndian
-#endif
-TEST_F(ByteIoTest, MAYBE_Test32SBitBigEndian) {
+TEST_F(ByteIoTest, Test32SBitBigEndian) {
   TestRead<int32_t, ByteReader<int32_t>::ReadBigEndian,
       sizeof(int32_t)>(true);
   TestWrite<int32_t, ByteWriter<int32_t>::WriteBigEndian,
       sizeof(int32_t)>(true);
 }
 
-// Disabled for UBSan: https://bugs.chromium.org/p/webrtc/issues/detail?id=5490
-#ifdef UNDEFINED_SANITIZER
-#define MAYBE_Test64SBitBigEndian DISABLED_Test64SBitBigEndian
-#else
-#define MAYBE_Test64SBitBigEndian Test64SBitBigEndian
-#endif
-TEST_F(ByteIoTest, MAYBE_Test64SBitBigEndian) {
+TEST_F(ByteIoTest, Test64SBitBigEndian) {
   TestRead<int64_t, ByteReader<int64_t>::ReadBigEndian,
       sizeof(int64_t)>(true);
   TestWrite<int64_t, ByteWriter<int64_t>::WriteBigEndian,
@@ -204,26 +197,14 @@ TEST_F(ByteIoTest, Test24SBitLittleEndian) {
   TestWrite<int32_t, ByteWriter<int32_t, 3>::WriteLittleEndian, 3>(false);
 }
 
-// Disabled for UBSan: https://bugs.chromium.org/p/webrtc/issues/detail?id=5490
-#ifdef UNDEFINED_SANITIZER
-#define MAYBE_Test32SBitLittleEndian DISABLED_Test32SBitLittleEndian
-#else
-#define MAYBE_Test32SBitLittleEndian Test32SBitLittleEndian
-#endif
-TEST_F(ByteIoTest, MAYBE_Test32SBitLittleEndian) {
+TEST_F(ByteIoTest, Test32SBitLittleEndian) {
   TestRead<int32_t, ByteReader<int32_t>::ReadLittleEndian,
       sizeof(int32_t)>(false);
   TestWrite<int32_t, ByteWriter<int32_t>::WriteLittleEndian,
       sizeof(int32_t)>(false);
 }
 
-// Disabled for UBSan: https://bugs.chromium.org/p/webrtc/issues/detail?id=5490
-#ifdef UNDEFINED_SANITIZER
-#define MAYBE_Test64SBitLittleEndian DISABLED_Test64SBitLittleEndian
-#else
-#define MAYBE_Test64SBitLittleEndian Test64SBitLittleEndian
-#endif
-TEST_F(ByteIoTest, MAYBE_Test64SBitLittleEndian) {
+TEST_F(ByteIoTest, Test64SBitLittleEndian) {
   TestRead<int64_t, ByteReader<int64_t>::ReadLittleEndian,
       sizeof(int64_t)>(false);
   TestWrite<int64_t, ByteWriter<int64_t>::WriteLittleEndian,