Reenable SecurityTest.NewOverflow on Windows, with clang fix

base/security_unittest.cc

Index: base/security_unittest.cc
diff --git a/base/security_unittest.cc b/base/security_unittest.cc
index af9d2bf19d3a52b15a53fdbd1032afe639336fac..17457d18681aa8f6ef59f085443ccf1ceb9eccee 100644
--- a/base/security_unittest.cc
+++ b/base/security_unittest.cc
@@ -87,14 +87,13 @@ void OverflowTestsSoftExpectTrue(bool overflow_detected) {
   }
 }
 
-#if defined(OS_IOS) || defined(OS_WIN) || defined(OS_LINUX)
+#if defined(OS_IOS) || defined(OS_LINUX)
 #define MAYBE_NewOverflow DISABLED_NewOverflow
 #else
 #define MAYBE_NewOverflow NewOverflow
 #endif
 // Test array[TooBig][X] and array[X][TooBig] allocations for int overflows.
 // IOS doesn't honor nothrow, so disable the test there.
-// Crashes on Windows Dbg builds, disable there as well.
 // Disabled on Linux because failing Linux Valgrind bot, and Valgrind exclusions
 // are not currently read. See http://crbug.com/582398
 TEST(SecurityTest, MAYBE_NewOverflow) {
@@ -102,16 +101,15 @@ TEST(SecurityTest, MAYBE_NewOverflow) {
   // We want something "dynamic" here, so that the compiler doesn't
   // immediately reject crazy arrays.
   const size_t kDynamicArraySize = HideValueFromCompiler(kArraySize);
-  // numeric_limits are still not constexpr until we switch to C++11, so we
-  // use an ugly cast.

[Nico, 2017/02/13 19:00:15]

unrelated, but while here i did this too

-  const size_t kMaxSizeT = ~static_cast<size_t>(0);
-  ASSERT_EQ(numeric_limits<size_t>::max(), kMaxSizeT);
+  const size_t kMaxSizeT = std::numeric_limits<size_t>::max();
   const size_t kArraySize2 = kMaxSizeT / kArraySize + 10;
   const size_t kDynamicArraySize2 = HideValueFromCompiler(kArraySize2);
   {
     std::unique_ptr<char[][kArraySize]> array_pointer(
         new (nothrow) char[kDynamicArraySize2][kArraySize]);
-    OverflowTestsSoftExpectTrue(!array_pointer);
+    // Prevent clang from optimizing away the whole test.
+    char* volatile p = reinterpret_cast<char*>(array_pointer.get());

[Sigurður Ásgeirsson, 2017/02/13 19:14:34]

Ah - that's where the volatile applies. In stolen moments on Friday I tried
making the integers volatile :/.
So casting an allocated pointer to volatile works around the the
malloc()-eliding?

+    OverflowTestsSoftExpectTrue(!p);
   }
   // On windows, the compiler prevents static array sizes of more than
   // 0x7fffffff (error C2148).
@@ -121,7 +119,9 @@ TEST(SecurityTest, MAYBE_NewOverflow) {
   {
     std::unique_ptr<char[][kArraySize2]> array_pointer(
         new (nothrow) char[kDynamicArraySize][kArraySize2]);
-    OverflowTestsSoftExpectTrue(!array_pointer);
+    // Prevent clang from optimizing away the whole test.
+    char* volatile p = array_pointer.get();
+    OverflowTestsSoftExpectTrue(!p);
   }
 #endif  // !defined(OS_WIN) || !defined(ARCH_CPU_64_BITS)
 }