fix bug for static init

Ugh! Static initialization of instance variables is a very bad idea.

This fix is taken from the Chromium code-base. It includes their
double-fix for ARM.

* https://codereview.chromium.org/24984004
* https://src.chromium.org/viewvc/chrome?revision=226099&view=revision
* https://code.google.com/p/webrtc/issues/detail?id=1777
This commit is contained in:
Christopher Dunn 2014-07-05 13:52:19 -07:00
parent 47f1577fd3
commit 28836b8acc
2 changed files with 12 additions and 2 deletions

View File

@ -133,7 +133,7 @@ public:
typedef Json::LargestUInt LargestUInt;
typedef Json::ArrayIndex ArrayIndex;
static const Value null;
static const Value& null;
/// Minimum signed integer value that can be stored in a Json::Value.
static const LargestInt minLargestInt;
/// Maximum signed integer value that can be stored in a Json::Value.

View File

@ -25,7 +25,17 @@
namespace Json {
const Value Value::null;
// This is a walkaround to avoid the static initialization of Value::null.
// kNull must be word-aligned to avoid crashing on ARM. We use an alignment of
// 8 (instead of 4) as a bit of future-proofing.
#if defined(__ARMEL__)
#define ALIGNAS(byte_alignment) __attribute__((aligned(byte_alignment)))
#else
#define ALIGNAS(byte_alignment)
#endif
static const unsigned char ALIGNAS(8) kNull[sizeof(Value)] = {0};
const Value& Value::null = reinterpret_cast<const Value&>(kNull);
const Int Value::minInt = Int(~(UInt(-1) / 2));
const Int Value::maxInt = Int(UInt(-1) / 2);
const UInt Value::maxUInt = UInt(-1);