Prevent sign extension for pointer trace values

base/trace_event/trace_event_impl.cc

Index: base/trace_event/trace_event_impl.cc
diff --git a/base/trace_event/trace_event_impl.cc b/base/trace_event/trace_event_impl.cc
index e2e250ed567ed6385a8ff9072f2a452bd5f0f4be..f469f2f6bcbaa650c7a3263699a22729d742ece1 100644
--- a/base/trace_event/trace_event_impl.cc
+++ b/base/trace_event/trace_event_impl.cc
@@ -261,7 +261,7 @@ void TraceEvent::AppendValueAsJSON(unsigned char type,
       // So as not to lose bits from a 64-bit pointer, output as a hex string.
       StringAppendF(
           out, "\"0x%" PRIx64 "\"",
-          static_cast<uint64_t>(reinterpret_cast<intptr_t>(value.as_pointer)));
+          static_cast<uint64_t>(reinterpret_cast<uintptr_t>(value.as_pointer)));

[caseq, 2016/06/09 16:59:13]

can we drop the inner one and do a reinterpret_cast<uint64_t>(value.as_pointer)
straight away?

[Kunihiko Sakamoto, 2016/06/10 05:19:24]

Unfortunately, that doesn't prevent sign extension.
http://stackoverflow.com/questions/22239752/convert-32-bit-pointer-to-64-bit-...
Looks like 2-step conversion is necessary.

       break;
     case TRACE_VALUE_TYPE_STRING:
     case TRACE_VALUE_TYPE_COPY_STRING: