QEvent: start to de-inline copy ctor and clone() of all subclasses

There's no advantage to them being inline: Absent de-virtualisation,
clone() is only supposed to be called through the vtable, and the copy
ctor is only supposed to be used in the implementation of clone().

And when the compiler de-virtualises, we don't want the code
duplication associated with inlining.

Enforce this by introducing new macros to hide the boilerplate.

This fixes missing out-of-line dtors in:
- QSinglePointEvent
- QApplicationStateChangeEvent
- QFutureCallOutEvent

Wrong covariant return in:
- QFutureCallOutEvent

And missing clone() reimplementations in:
- QCloseEvent
- QIconDragEvent
- QShowEvent
- QHideEvent
- QDragEnterEvent
- QDragLeaveEvent

While these don't carry extra data or members, a dynamic_cast of the
result of clone() as well as using the expected covariant return value
would fail:

   QShowEvent *e = ~~~;
   QShowEvent *e2 = e->clone(); // ERROR: converting QEvent* to QShowEvent*

Check that reimplementing clone() is binary compatible (covariant
returns may change the numerical pointer value returned, cf.
https://community.kde.org/Policies/Binary_Compatibility_Issues_With_C%2B%2B).

The copy-assignment operator stays inline for the time being, as the
goal is to = delete it in the future.

This patch covers, roughly, QtCore and QtGui.

[ChangeLog][QtGui][QEvent subclasses] Fixed missing clone()
reimplementations on QCloseEvent, QIconDragEvent, QShowEvent,
QHideEvent, QDragEnterEvent, and QDragLeaveEvent.

Task-number: QTBUG-45582
Task-number: QTBUG-97601
Change-Id: Ib8a0519dbe85a7a8da61050d48be338004dfa69a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/corelib/thread/qfutureinterface.cpp b/src/corelib/thread/qfutureinterface.cpp
index 0fde190bc0..71d6670538 100644
--- a/src/corelib/thread/qfutureinterface.cpp
+++ b/src/corelib/thread/qfutureinterface.cpp
@@ -74,6 +74,8 @@ const auto suspendingOrSuspended =
 QFutureCallOutInterface::~QFutureCallOutInterface()
     = default;
 
+Q_IMPL_EVENT_COMMON(QFutureCallOutEvent)
+
 QFutureInterfaceBase::QFutureInterfaceBase(State initialState)
     : d(new QFutureInterfaceBasePrivate(initialState))
 { }