Prevent clang from optimizing away a malloc in a test.

base/security_unittest.cc

Index: base/security_unittest.cc
diff --git a/base/security_unittest.cc b/base/security_unittest.cc
index a7e3bc4bd6e72e95097fa198702337a7664fc7ac..5625129730e62d63c07c0870b0cd349028c3a939 100644
--- a/base/security_unittest.cc
+++ b/base/security_unittest.cc
@@ -42,7 +42,8 @@ int OnNoMemory(size_t) {
 
 void ExhaustMemoryWithMalloc() {
   for (;;) {
-    void* buf = malloc(kLargePermittedAllocation);
+    // Without the |volatile|, clang optimizez away the allocation.

[scottmg, 2015/01/22 19:46:21]

optimizes

[Will Harris, 2015/01/22 19:46:45]

ah. interesting.  We actually have HideValueFromCompiler below whose purpose is
to solve this generically.  Perhaps HideValueFromCompiler could be changed to
understand clang, and then used here instead?

[Nico, 2015/01/22 19:48:31]

What's wrong with volatile? That's kind of the language-supported way of doing
this (and also what we use in other files doing similar things, see links to
other cls in the cl description.)

[Nico, 2015/01/22 19:48:31]

Done.

+    void* volatile buf = malloc(kLargePermittedAllocation);
     if (!buf)
       break;
   }