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Ensure shared_null(s) are statically initialized on VS 2010

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This removes const qualification on data members of QConst*Data, which
was subjecting QString's and QByteArray's shared_null to the "order of
static initialization fiasco", with up-to-date VS 2010.

Furthermore, the const qualification in the places where it was removed
had little meaning and no value. It was unnecessary. As such, "Const"
was removed from the struct's names and "Static" used in its place, to
imply their usefulness in supporting statically-initialized fixed-size
(string and byte) containers.

A test case was added to QArrayData as that is meant to replace both
QStringData and QByteArrayData in the near future.

VS issue reported at:
https://connect.microsoft.com/VisualStudio/feedback/details/716461

Change-Id: I3d86f2a387a68f359bb3d8f4d10cf3da51c6ecf7
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>
This commit is contained in:
João Abecasis 2012-01-04 14:30:42 +01:00 committed by Qt by Nokia
parent 9a890a519e
commit fed603fde5
6 changed files with 60 additions and 43 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
src/corelib/tools/qbytearray.cpp
View File

@ -614,9 +614,9 @@ static inline char qToLower(char c)
return c;
}
const QConstByteArrayData<1> QByteArray::shared_null = { { Q_REFCOUNT_INITIALIZE_STATIC,
const QStaticByteArrayData<1> QByteArray::shared_null = { { Q_REFCOUNT_INITIALIZE_STATIC,
0, 0, 0, { 0 } }, { 0 } };
const QConstByteArrayData<1> QByteArray::shared_empty = { { Q_REFCOUNT_INITIALIZE_STATIC,
const QStaticByteArrayData<1> QByteArray::shared_empty = { { Q_REFCOUNT_INITIALIZE_STATIC,
0, 0, 0, { 0 } }, { 0 } };
/*!

28
src/corelib/tools/qbytearray.h
View File

@ -133,24 +133,24 @@ struct QByteArrayData
inline const char *data() const { return d + sizeof(qptrdiff) + offset; }
};
template<int N> struct QConstByteArrayData
template<int N> struct QStaticByteArrayData
{
const QByteArrayData ba;
const char data[N + 1];
QByteArrayData ba;
char data[N + 1];
};
template<int N> struct QConstByteArrayDataPtr
template<int N> struct QStaticByteArrayDataPtr
{
const QConstByteArrayData<N> *ptr;
const QStaticByteArrayData<N> *ptr;
};
#if defined(Q_COMPILER_LAMBDA)
# define QByteArrayLiteral(str) ([]() -> QConstByteArrayDataPtr<sizeof(str) - 1> { \
# define QByteArrayLiteral(str) ([]() -> QStaticByteArrayDataPtr<sizeof(str) - 1> { \
enum { Size = sizeof(str) - 1 }; \
static const QConstByteArrayData<Size> qbytearray_literal = \
static const QStaticByteArrayData<Size> qbytearray_literal = \
{ { Q_REFCOUNT_INITIALIZE_STATIC, Size, 0, 0, { 0 } }, str }; \
QConstByteArrayDataPtr<Size> holder = { &qbytearray_literal }; \
QStaticByteArrayDataPtr<Size> holder = { &qbytearray_literal }; \
return holder; }())
#elif defined(Q_CC_GNU)
@ -161,9 +161,9 @@ template<int N> struct QConstByteArrayDataPtr
# define QByteArrayLiteral(str) \
__extension__ ({ \
enum { Size = sizeof(str) - 1 }; \
static const QConstByteArrayData<Size> qbytearray_literal = \
static const QStaticByteArrayData<Size> qbytearray_literal = \
{ { Q_REFCOUNT_INITIALIZE_STATIC, Size, 0, 0, { 0 } }, str }; \
QConstByteArrayDataPtr<Size> holder = { &qbytearray_literal }; \
QStaticByteArrayDataPtr<Size> holder = { &qbytearray_literal }; \
holder; })
#endif
@ -378,16 +378,16 @@ public:
bool isNull() const;
template <int n>
inline QByteArray(const QConstByteArrayData<n> &dd)
inline QByteArray(const QStaticByteArrayData<n> &dd)
: d(const_cast<QByteArrayData *>(&dd.str)) {}
template <int N>
Q_DECL_CONSTEXPR inline QByteArray(QConstByteArrayDataPtr<N> dd)
Q_DECL_CONSTEXPR inline QByteArray(QStaticByteArrayDataPtr<N> dd)
: d(const_cast<QByteArrayData *>(&dd.ptr->ba)) {}
private:
operator QNoImplicitBoolCast() const;
static const QConstByteArrayData<1> shared_null;
static const QConstByteArrayData<1> shared_empty;
static const QStaticByteArrayData<1> shared_null;
static const QStaticByteArrayData<1> shared_empty;
Data *d;
QByteArray(Data *dd, int /*dummy*/, int /*dummy*/) : d(dd) {}
void realloc(int alloc);

4
src/corelib/tools/qstring.cpp
View File

@ -798,8 +798,8 @@ const QString::Null QString::null = { };
\sa split()
*/
const QConstStringData<1> QString::shared_null = { { Q_REFCOUNT_INITIALIZE_STATIC, 0, 0, false, { 0 } }, { 0 } };
const QConstStringData<1> QString::shared_empty = { { Q_REFCOUNT_INITIALIZE_STATIC, 0, 0, false, { 0 } }, { 0 } };
const QStaticStringData<1> QString::shared_null = { { Q_REFCOUNT_INITIALIZE_STATIC, 0, 0, false, { 0 } }, { 0 } };
const QStaticStringData<1> QString::shared_empty = { { Q_REFCOUNT_INITIALIZE_STATIC, 0, 0, false, { 0 } }, { 0 } };
int QString::grow(int size)
{

42
src/corelib/tools/qstring.h
View File

@ -90,27 +90,27 @@ struct QStringData {
inline const ushort *data() const { return d + sizeof(qptrdiff)/sizeof(ushort) + offset; }
};
template<int N> struct QConstStringData;
template<int N> struct QConstStringDataPtr
template<int N> struct QStaticStringData;
template<int N> struct QStaticStringDataPtr
{
const QConstStringData<N> *ptr;
const QStaticStringData<N> *ptr;
};
#if defined(Q_COMPILER_UNICODE_STRINGS)
template<int N> struct QConstStringData
template<int N> struct QStaticStringData
{
const QStringData str;
const char16_t data[N + 1];
QStringData str;
char16_t data[N + 1];
};
#define QT_UNICODE_LITERAL_II(str) u"" str
#elif defined(Q_OS_WIN) || (defined(__SIZEOF_WCHAR_T__) && __SIZEOF_WCHAR_T__ == 2) || defined(WCHAR_MAX) && (WCHAR_MAX - 0 < 65536)
// wchar_t is 2 bytes
template<int N> struct QConstStringData
template<int N> struct QStaticStringData
{
const QStringData str;
const wchar_t data[N + 1];
QStringData str;
wchar_t data[N + 1];
};
#if defined(Q_CC_MSVC)
@ -120,21 +120,21 @@ template<int N> struct QConstStringData
#endif
#else
template<int N> struct QConstStringData
template<int N> struct QStaticStringData
{
const QStringData str;
const ushort data[N + 1];
QStringData str;
ushort data[N + 1];
};
#endif
#if defined(QT_UNICODE_LITERAL_II)
# define QT_UNICODE_LITERAL(str) QT_UNICODE_LITERAL_II(str)
# if defined(Q_COMPILER_LAMBDA)
# define QStringLiteral(str) ([]() -> QConstStringDataPtr<sizeof(QT_UNICODE_LITERAL(str))/2 - 1> { \
# define QStringLiteral(str) ([]() -> QStaticStringDataPtr<sizeof(QT_UNICODE_LITERAL(str))/2 - 1> { \
enum { Size = sizeof(QT_UNICODE_LITERAL(str))/2 - 1 }; \
static const QConstStringData<Size> qstring_literal = \
static const QStaticStringData<Size> qstring_literal = \
{ { Q_REFCOUNT_INITIALIZE_STATIC, Size, 0, 0, { 0 } }, QT_UNICODE_LITERAL(str) }; \
QConstStringDataPtr<Size> holder = { &qstring_literal }; \
QStaticStringDataPtr<Size> holder = { &qstring_literal }; \
return holder; }())
# elif defined(Q_CC_GNU)
@ -145,9 +145,9 @@ template<int N> struct QConstStringData
# define QStringLiteral(str) \
__extension__ ({ \
enum { Size = sizeof(QT_UNICODE_LITERAL(str))/2 - 1 }; \
static const QConstStringData<Size> qstring_literal = \
static const QStaticStringData<Size> qstring_literal = \
{ { Q_REFCOUNT_INITIALIZE_STATIC, Size, 0, 0, { 0 } }, QT_UNICODE_LITERAL(str) }; \
QConstStringDataPtr<Size> holder = { &qstring_literal }; \
QStaticStringDataPtr<Size> holder = { &qstring_literal }; \
holder; })
# endif
#endif
@ -586,9 +586,9 @@ public:
QString(int size, Qt::Initialization);
template <int n>
inline QString(const QConstStringData<n> &dd) : d(const_cast<QStringData *>(&dd.str)) {}
inline QString(const QStaticStringData<n> &dd) : d(const_cast<QStringData *>(&dd.str)) {}
template <int N>
Q_DECL_CONSTEXPR inline QString(QConstStringDataPtr<N> dd) : d(const_cast<QStringData *>(&dd.ptr->str)) {}
Q_DECL_CONSTEXPR inline QString(QStaticStringDataPtr<N> dd) : d(const_cast<QStringData *>(&dd.ptr->str)) {}
private:
#if defined(QT_NO_CAST_FROM_ASCII) && !defined(Q_NO_DECLARED_NOT_DEFINED)
@ -600,8 +600,8 @@ private:
QString &operator=(const QByteArray &a);
#endif
static const QConstStringData<1> shared_null;
static const QConstStringData<1> shared_empty;
static const QStaticStringData<1> shared_null;
static const QStaticStringData<1> shared_empty;
Data *d;
inline QString(Data *dd, int /*dummy*/) : d(dd) {}

8
src/corelib/tools/qstringbuilder.h
View File

@ -249,9 +249,9 @@ template <> struct QConcatenable<QString> : private QAbstractConcatenable
#endif
};
template <int N> struct QConcatenable<QConstStringDataPtr<N> > : private QAbstractConcatenable
template <int N> struct QConcatenable<QStaticStringDataPtr<N> > : private QAbstractConcatenable
{
typedef QConstStringDataPtr<N> type;
typedef QStaticStringDataPtr<N> type;
typedef QString ConvertTo;
enum { ExactSize = true };
static int size(const type &) { return N; }
@ -363,9 +363,9 @@ template <> struct QConcatenable<QByteArray> : private QAbstractConcatenable
}
};
template <int N> struct QConcatenable<QConstByteArrayDataPtr<N> > : private QAbstractConcatenable
template <int N> struct QConcatenable<QStaticByteArrayDataPtr<N> > : private QAbstractConcatenable
{
typedef QConstByteArrayDataPtr<N> type;
typedef QStaticByteArrayDataPtr<N> type;
typedef QByteArray ConvertTo;
enum { ExactSize = false };
static int size(const type &) { return N; }

17
tests/auto/corelib/tools/qarraydata/tst_qarraydata.cpp
View File

@ -46,6 +46,23 @@
#include "simplevector.h"
struct SharedNullVerifier
{
SharedNullVerifier()
{
Q_ASSERT(QArrayData::shared_null.ref.isStatic());
Q_ASSERT(QArrayData::shared_null.ref.isShared());
Q_ASSERT(QArrayData::shared_null.ref.isSharable());
}
};
// This is meant to verify/ensure that shared_null is not being dynamically
// initialized and stays away from the order-of-static-initialization fiasco.
//
// Of course, if this was to fail, qmake and the build should have crashed and
// burned before we ever got to this point :-)
SharedNullVerifier globalInit;
class tst_QArrayData : public QObject
{
Q_OBJECT