Prevent repeated instantiations of some qRegisterNormalizedMetaType<>s [1/N] (QtGui)

Create macros that wrap the magic developed in
7d63efc16f65f98c657caa90e0d7e9b72a879ade and apply it to all
Q_DECLARE_METATYPE invocations that show up in Clang -ftime-trace for
a PCH'ed QtGui build.

Effects on compile times:

Clang 10 -ftme-trace:

  $ ClangBuildAnalyzer --analyze qtgui-before.trace  | head -n6
  Analyzing build trace from 'qtgui-before.trace'...
  **** Time summary:
  Compilation (523 times):
    Parsing (frontend):          628.3 s
    Codegen & opts (backend):    304.5 s

  $ ClangBuildAnalyzer --analyze qtgui-after.trace  | head -n6
  Analyzing build trace from 'qtgui-after.trace'...
  **** Time summary:
  Compilation (523 times):
    Parsing (frontend):          546.0 s
    Codegen & opts (backend):    304.4 s

GCC 11 time (bash builtin):

before:

  $ time for ((i=0; i < 3; ++i)) do touch src/gui/painting/qpolygon.h ; ninja libQt6Gui.so; done

  real    4m13,539s
  user    49m24,416s
  sys     3m18,177s

after:

  $ time for ((i=0; i < 3; ++i)) do touch src/gui/painting/qpolygon.h ; ninja libQt6Gui.so; done

  real    3m55,697s
  user    45m19,941s
  sys     3m7,370s

Task-number: QTBUG-97601
Pick-to: 6.3
Change-Id: Ia8e37a58937568a7ed21cfeb4b27274deca4d53b
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

doc/global/qt-cpp-defines.qdocconf

@@ -177,6 +177,8 @@ Cpp.ignoredirectives    += \
                           Q_CLASSINFO \
                           Q_DECLARE_INTERFACE \
                           Q_DECLARE_METATYPE \
+                          QT_DECL_METATYPE_EXTERN \
+                          QT_IMPL_METATYPE_EXTERN \
                           Q_DECLARE_OPERATORS_FOR_FLAGS \
                           Q_DECLARE_PRIVATE \
                           Q_DECLARE_PRIVATE_D \

src/corelib/global/qfloat16.cpp

@@ -44,6 +44,8 @@
 
 QT_BEGIN_NAMESPACE
 
+QT_IMPL_METATYPE_EXTERN(qfloat16)
+
 /*!
     \class qfloat16
     \keyword 16-bit Floating Point Support

src/corelib/global/qfloat16.h

@@ -367,7 +367,7 @@ inline auto qHypot(qfloat16 x, qfloat16 y, qfloat16 z)
 
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE(qfloat16)
+QT_DECL_METATYPE_EXTERN(qfloat16, Q_CORE_EXPORT)
 
 namespace std {
 template<>

src/corelib/io/qfileinfo.cpp

@@ -46,6 +46,8 @@
 
 QT_BEGIN_NAMESPACE
 
+QT_IMPL_METATYPE_EXTERN(QFileInfo)
+
 QString QFileInfoPrivate::getFileName(QAbstractFileEngine::FileName name) const
 {
     if (cache_enabled && !fileNames[(int)name].isNull())

src/corelib/io/qfileinfo.h

@@ -212,6 +212,6 @@ Q_CORE_EXPORT QDebug operator<<(QDebug, const QFileInfo &);
 
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE(QFileInfo)
+QT_DECL_METATYPE_EXTERN(QFileInfo, Q_CORE_EXPORT)
 
 #endif // QFILEINFO_H

src/corelib/io/qstorageinfo.cpp

@@ -44,6 +44,8 @@
 
 QT_BEGIN_NAMESPACE
 
+QT_IMPL_METATYPE_EXTERN(QStorageInfo)
+
 /*!
     \class QStorageInfo
     \inmodule QtCore

src/corelib/io/qstorageinfo.h

@@ -120,6 +120,6 @@ Q_CORE_EXPORT QDebug operator<<(QDebug debug, const QStorageInfo &);
 
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE(QStorageInfo)
+QT_DECL_METATYPE_EXTERN(QStorageInfo, Q_CORE_EXPORT)
 
 #endif // QSTORAGEINFO_H

src/corelib/itemmodels/qabstractitemmodel.cpp

@@ -60,8 +60,7 @@ QT_BEGIN_NAMESPACE
 
 Q_LOGGING_CATEGORY(lcCheckIndex, "qt.core.qabstractitemmodel.checkindex")
 
-int qRegisterNormalizedMetaType_QList_QModelIndex(const QByteArray &name)
-{ return qRegisterNormalizedMetaTypeImplementation<QList<QModelIndex>>(name); }
+QT_IMPL_METATYPE_EXTERN(QModelIndexList)
 
 QPersistentModelIndexData *QPersistentModelIndexData::create(const QModelIndex &index)
 {

src/corelib/itemmodels/qabstractitemmodel.h

@@ -537,12 +537,8 @@ inline Qt::ItemFlags QModelIndex::flags() const
 inline size_t qHash(const QModelIndex &index, size_t seed = 0) noexcept
 { return size_t((size_t(index.row()) << 4) + size_t(index.column()) + index.internalId()) ^ seed; }
 
-Q_CORE_EXPORT int qRegisterNormalizedMetaType_QList_QModelIndex(const QByteArray &name);
-template <> inline int qRegisterNormalizedMetaType<QList<QModelIndex>>(const QByteArray &name)
-{ return qRegisterNormalizedMetaType_QList_QModelIndex(name); }
-
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE(QModelIndexList)
+QT_DECL_METATYPE_EXTERN(QModelIndexList, Q_CORE_EXPORT)
 
 #endif // QABSTRACTITEMMODEL_H

src/corelib/itemmodels/qitemselectionmodel.cpp

@@ -50,6 +50,9 @@
 
 QT_BEGIN_NAMESPACE
 
+QT_IMPL_METATYPE_EXTERN(QItemSelectionRange)
+QT_IMPL_METATYPE_EXTERN(QItemSelection)
+
 /*!
     \class QItemSelectionRange
     \inmodule QtCore

src/corelib/itemmodels/qitemselectionmodel.h

@@ -238,7 +238,7 @@ Q_CORE_EXPORT QDebug operator<<(QDebug, const QItemSelectionRange &);
 
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE(QItemSelectionRange)
-Q_DECLARE_METATYPE(QItemSelection)
+QT_DECL_METATYPE_EXTERN(QItemSelectionRange, Q_CORE_EXPORT)
+QT_DECL_METATYPE_EXTERN(QItemSelection, Q_CORE_EXPORT)
 
 #endif // QITEMSELECTIONMODEL_H

src/corelib/kernel/qdeadlinetimer.cpp

@@ -43,6 +43,8 @@
 
 QT_BEGIN_NAMESPACE
 
+QT_IMPL_METATYPE_EXTERN(QDeadlineTimer)
+
 namespace {
     class TimeReference
     {

src/corelib/kernel/qdeadlinetimer.h

@@ -224,6 +224,6 @@ Q_DECLARE_SHARED(QDeadlineTimer)
 
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE(QDeadlineTimer)
+QT_DECL_METATYPE_EXTERN(QDeadlineTimer, Q_CORE_EXPORT)
 
 #endif // QDEADLINETIMER_H

src/corelib/kernel/qmetatype.cpp

@@ -97,6 +97,7 @@ QT_BEGIN_NAMESPACE
 
 #define NS(x) QT_PREPEND_NAMESPACE(x)
 
+QT_IMPL_METATYPE_EXTERN_TAGGED(QtMetaTypePrivate::QPairVariantInterfaceImpl, QPairVariantInterfaceImpl)
 
 namespace {
 struct DefinedTypesFilter {

src/corelib/kernel/qmetatype.h

@@ -1257,19 +1257,36 @@ int qRegisterNormalizedMetaTypeImplementation(const QT_PREPEND_NAMESPACE(QByteAr
 // This primary template calls the -Implementation, like all other specialisations should.
 // But the split allows to
 // - in a header:
-//   - declare, but not define, a specialization of this template
-//   - add an explicit instantiation declaration (extern template ...)
+//   - define a specialization of this template calling an out-of-line function
+//     (QT_DECL_METATYPE_EXTERN{,_TAGGED})
 // - in the .cpp file:
-//   - define the specialization to call the -Implementation
-//   - add an explicit instantiation definition
-// This prevents the compiler from taking the leeway for inline functions in
-// [temp.explicit]/13 Note 4
+//   - define the out-of-line wrapper to call the -Implementation
+//     (QT_IMPL_METATYPE_EXTERN{,_TAGGED})
+// The _TAGGED variants let you choose a tag (must be a C identifier) to disambiguate
+// the out-of-line function; the non-_TAGGED variants use the passed class name as tag.
 template <typename T>
 int qRegisterNormalizedMetaType(const QT_PREPEND_NAMESPACE(QByteArray) &normalizedTypeName)
 {
     return qRegisterNormalizedMetaTypeImplementation<T>(normalizedTypeName);
 }
 
+#define QT_DECL_METATYPE_EXTERN_TAGGED(TYPE, TAG, EXPORT) \
+    QT_BEGIN_NAMESPACE \
+    EXPORT int qRegisterNormalizedMetaType_ ## TAG (const QByteArray &); \
+    template <> inline int qRegisterNormalizedMetaType< TYPE >(const QByteArray &name) \
+    { return qRegisterNormalizedMetaType_ ## TAG (name); } \
+    QT_END_NAMESPACE \
+    Q_DECLARE_METATYPE(TYPE) \
+    /* end */
+#define QT_IMPL_METATYPE_EXTERN_TAGGED(TYPE, TAG) \
+    int qRegisterNormalizedMetaType_ ## TAG (const QByteArray &name) \
+    { return qRegisterNormalizedMetaTypeImplementation< TYPE >(name); } \
+    /* end */
+#define QT_DECL_METATYPE_EXTERN(TYPE, EXPORT) \
+    QT_DECL_METATYPE_EXTERN_TAGGED(TYPE, TYPE, EXPORT)
+#define QT_IMPL_METATYPE_EXTERN(TYPE) \
+    QT_IMPL_METATYPE_EXTERN_TAGGED(TYPE, TYPE)
+
 template <typename T>
 int qRegisterMetaType(const char *typeName)
 {
@@ -2521,6 +2538,7 @@ constexpr const QtPrivate::QMetaTypeInterface *const qt_incomplete_metaTypeArray
 
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE(QtMetaTypePrivate::QPairVariantInterfaceImpl)
+QT_DECL_METATYPE_EXTERN_TAGGED(QtMetaTypePrivate::QPairVariantInterfaceImpl,
+                               QPairVariantInterfaceImpl, Q_CORE_EXPORT)
 
 #endif // QMETATYPE_H

src/corelib/kernel/qsocketnotifier.cpp

@@ -58,6 +58,9 @@ QT_BEGIN_NAMESPACE
 Q_DECLARE_LOGGING_CATEGORY(lcSocketNotifierDeprecation)
 Q_LOGGING_CATEGORY(lcSocketNotifierDeprecation, "qt.core.socketnotifier_deprecation");
 
+QT_IMPL_METATYPE_EXTERN_TAGGED(QSocketNotifier::Type, QSocketNotifier_Type)
+QT_IMPL_METATYPE_EXTERN(QSocketDescriptor)
+
 class QSocketNotifierPrivate : public QObjectPrivate
 {
     Q_DECLARE_PUBLIC(QSocketNotifier)

src/corelib/kernel/qsocketnotifier.h

@@ -137,7 +137,8 @@ private:
 };
 
 QT_END_NAMESPACE
-Q_DECLARE_METATYPE(QSocketNotifier::Type)
-Q_DECLARE_METATYPE(QSocketDescriptor)
+
+QT_DECL_METATYPE_EXTERN_TAGGED(QSocketNotifier::Type, QSocketNotifier_Type, Q_CORE_EXPORT)
+QT_DECL_METATYPE_EXTERN(QSocketDescriptor, Q_CORE_EXPORT)
 
 #endif // QSOCKETNOTIFIER_H

src/corelib/serialization/qcborcommon.cpp

@@ -46,6 +46,8 @@
 
 QT_BEGIN_NAMESPACE
 
+QT_IMPL_METATYPE_EXTERN(QCborTag)
+
 #include <cborerrorstrings.c>
 
 /*!

src/corelib/serialization/qcborcommon.h

@@ -151,7 +151,7 @@ enum class QCborNegativeInteger : quint64 {};
 
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE(QCborTag)
+QT_DECL_METATYPE_EXTERN(QCborTag, Q_CORE_EXPORT)
 
 // To avoid changing namespace we need to reinstate defines, even though our .cpp
 // will then have to remove them again.

src/corelib/tools/qversionnumber.cpp

@@ -57,6 +57,9 @@
 
 QT_BEGIN_NAMESPACE
 
+QT_IMPL_METATYPE_EXTERN(QVersionNumber)
+QT_IMPL_METATYPE_EXTERN(QTypeRevision)
+
 /*!
     \class QVersionNumber
     \inmodule QtCore

src/corelib/tools/qversionnumber.h

@@ -494,7 +494,7 @@ Q_CORE_EXPORT QDebug operator<<(QDebug, const QTypeRevision &revision);
 
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE(QVersionNumber)
-Q_DECLARE_METATYPE(QTypeRevision)
+QT_DECL_METATYPE_EXTERN(QVersionNumber, Q_CORE_EXPORT)
+QT_DECL_METATYPE_EXTERN(QTypeRevision, Q_CORE_EXPORT)
 
 #endif // QVERSIONNUMBER_H

src/dbus/qdbuserror.cpp

@@ -53,6 +53,8 @@
 
 QT_BEGIN_NAMESPACE
 
+QT_IMPL_METATYPE_EXTERN(QDBusError)
+
 static constexpr const auto errorMessages = qOffsetStringArray(
     "NoError",
     "other",

src/dbus/qdbuserror.h

@@ -140,7 +140,7 @@ Q_DBUS_EXPORT QDebug operator<<(QDebug, const QDBusError &);
 
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE(QDBusError)
+QT_DECL_METATYPE_EXTERN(QDBusError, Q_DBUS_EXPORT)
 #else
 QT_BEGIN_NAMESPACE
 class Q_DBUS_EXPORT QDBusError {}; // dummy class for moc

src/dbus/qdbusextratypes.cpp

@@ -44,6 +44,10 @@
 
 QT_BEGIN_NAMESPACE
 
+QT_IMPL_METATYPE_EXTERN(QDBusVariant)
+QT_IMPL_METATYPE_EXTERN(QDBusObjectPath)
+QT_IMPL_METATYPE_EXTERN(QDBusSignature)
+
 void QDBusObjectPath::doCheck()
 {
     if (!QDBusUtil::isValidObjectPath(m_path)) {

src/dbus/qdbusextratypes.h

@@ -189,9 +189,9 @@ inline bool operator==(const QDBusVariant &v1, const QDBusVariant &v2)
 
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE(QDBusVariant)
-Q_DECLARE_METATYPE(QDBusObjectPath)
-Q_DECLARE_METATYPE(QDBusSignature)
+QT_DECL_METATYPE_EXTERN(QDBusVariant, Q_DBUS_EXPORT)
+QT_DECL_METATYPE_EXTERN(QDBusObjectPath, Q_DBUS_EXPORT)
+QT_DECL_METATYPE_EXTERN(QDBusSignature, Q_DBUS_EXPORT)
 
 #endif // QT_NO_DBUS
 #endif

src/dbus/qdbusmessage.cpp

@@ -56,6 +56,8 @@
 
 QT_BEGIN_NAMESPACE
 
+QT_IMPL_METATYPE_EXTERN(QDBusMessage)
+
 static_assert(QDBusMessage::InvalidMessage == DBUS_MESSAGE_TYPE_INVALID);
 static_assert(QDBusMessage::MethodCallMessage == DBUS_MESSAGE_TYPE_METHOD_CALL);
 static_assert(QDBusMessage::ReplyMessage == DBUS_MESSAGE_TYPE_METHOD_RETURN);

src/dbus/qdbusmessage.h

@@ -131,7 +131,7 @@ Q_DBUS_EXPORT QDebug operator<<(QDebug, const QDBusMessage &);
 
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE(QDBusMessage)
+QT_DECL_METATYPE_EXTERN(QDBusMessage, Q_DBUS_EXPORT)
 
 #else
 class Q_DBUS_EXPORT QDBusMessage {}; // dummy class for moc

src/dbus/qdbusunixfiledescriptor.cpp

@@ -48,6 +48,8 @@ QT_BEGIN_NAMESPACE
 
 #ifndef QT_NO_DBUS
 
+QT_IMPL_METATYPE_EXTERN(QDBusUnixFileDescriptor)
+
 /*!
     \class QDBusUnixFileDescriptor
     \inmodule QtDBus

src/dbus/qdbusunixfiledescriptor.h

@@ -85,7 +85,7 @@ Q_DECLARE_SHARED(QDBusUnixFileDescriptor)
 
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE(QDBusUnixFileDescriptor)
+QT_DECL_METATYPE_EXTERN(QDBusUnixFileDescriptor, Q_DBUS_EXPORT)
 
 #endif // QT_NO_DBUS
 #endif // QDBUSUNIXFILEDESCRIPTOR_H

src/gui/kernel/qsurface.cpp

@@ -44,6 +44,7 @@
 
 QT_BEGIN_NAMESPACE
 
+QT_IMPL_METATYPE_EXTERN_TAGGED(QSurface*, QSurface_ptr)
 
 /*!
     \class QSurface

src/gui/kernel/qsurface.h

@@ -96,6 +96,6 @@ protected:
 
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE(QSurface*)
+QT_DECL_METATYPE_EXTERN_TAGGED(QSurface*, QSurface_ptr, Q_GUI_EXPORT)
 
 #endif //QSURFACE_H

src/gui/text/qtextoption.cpp

@@ -43,6 +43,8 @@
 
 QT_BEGIN_NAMESPACE
 
+QT_IMPL_METATYPE_EXTERN_TAGGED(QTextOption::Tab, QTextOption_Tab)
+
 struct QTextOptionPrivate
 {
     QList<QTextOption::Tab> tabStops;

src/gui/text/qtextoption.h

@@ -151,6 +151,6 @@ inline void QTextOption::setTabStopDistance(qreal atabStop)
 
 QT_END_NAMESPACE
 
-Q_DECLARE_METATYPE( QTextOption::Tab )
+QT_DECL_METATYPE_EXTERN_TAGGED(QTextOption::Tab, QTextOption_Tab, Q_GUI_EXPORT)
 
 #endif // QTEXTOPTION_H