From d18a9dd977a59bf735ed3b6a19e101d4b26a1cef Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Mon, 3 Jul 2023 07:43:28 +0200
Subject: [PATCH] QEventLoopLocker: use visit() to DRY ctors

Collapse all three Private ctors into one (void*, Type) one.

Task-number: QTBUG-114793
Pick-to: 6.6
Change-Id: Ia5c67c0ffdcddfdecb38fe3e095d60f6761f1160
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
---
 src/corelib/kernel/qeventloop.cpp | 50 ++++++++++++++-----------------
 src/corelib/kernel/qeventloop.h   |  7 +++++
 2 files changed, 29 insertions(+), 28 deletions(-)

diff --git a/src/corelib/kernel/qeventloop.cpp b/src/corelib/kernel/qeventloop.cpp
index f3ddc84758..768175257f 100644
--- a/src/corelib/kernel/qeventloop.cpp
+++ b/src/corelib/kernel/qeventloop.cpp
@@ -312,35 +312,11 @@ void QEventLoop::quit()
 
 class QEventLoopLockerPrivate
 {
-    friend class QEventLoopLocker;
 public:
-    explicit QEventLoopLockerPrivate(QEventLoopPrivate *loop)
-      : QEventLoopLockerPrivate(loop, EventLoop)
-    {
-        loop->ref();
-    }
-
-    explicit QEventLoopLockerPrivate(QThreadPrivate *thread)
-      : QEventLoopLockerPrivate(thread, Thread)
-    {
-        thread->ref();
-    }
-
-    explicit QEventLoopLockerPrivate(QCoreApplicationPrivate *app)
-      : QEventLoopLockerPrivate(app, Application)
-    {
-        app->ref();
-    }
-
-private:
+    using Type = QEventLoopLocker::Type;
     QEventLoopPrivate *loop() const { return static_cast<QEventLoopPrivate *>(pointer()); }
     QThreadPrivate *thread() const { return static_cast<QThreadPrivate *>(pointer()); }
     QCoreApplicationPrivate *app() const { return static_cast<QCoreApplicationPrivate *>(pointer()); }
-    enum Type {
-        EventLoop,
-        Thread,
-        Application
-    };
     explicit QEventLoopLockerPrivate(void *ptr, Type t) noexcept
         : p{quintptr(ptr) | quintptr(t)} {}
     quintptr p;
@@ -348,11 +324,19 @@ private:
     Type type() const { return Type(p & TypeMask); }
     void *pointer() const { return reinterpret_cast<void *>(p & ~TypeMask); }
 };
+namespace {
 // If any of these trigger, the Type bits will interfere with the pointer values:
 static_assert(alignof(QEventLoopPrivate) >= 4);
 static_assert(alignof(QThreadPrivate) >= 4);
 static_assert(alignof(QCoreApplicationPrivate) >= 4);
 
+template <typename Private>
+Private *o2p(QObject *o)
+{
+    return static_cast<Private*>(QObjectPrivate::get(o));
+}
+} // unnamed namespace
+
 /*!
     \class QEventLoopLocker
     \inmodule QtCore
@@ -381,7 +365,8 @@ static_assert(alignof(QCoreApplicationPrivate) >= 4);
     \sa QCoreApplication::quit(), QCoreApplication::isQuitLockEnabled()
  */
 QEventLoopLocker::QEventLoopLocker()
-  : d_ptr(new QEventLoopLockerPrivate(static_cast<QCoreApplicationPrivate*>(QObjectPrivate::get(QCoreApplication::instance()))))
+    : QEventLoopLocker{o2p<QCoreApplicationPrivate>(QCoreApplication::instance()),
+                       Type::Application}
 {
 
 }
@@ -394,7 +379,7 @@ QEventLoopLocker::QEventLoopLocker()
     \sa QEventLoop::quit()
  */
 QEventLoopLocker::QEventLoopLocker(QEventLoop *loop)
-  : d_ptr(new QEventLoopLockerPrivate(static_cast<QEventLoopPrivate*>(QObjectPrivate::get(loop))))
+    : QEventLoopLocker{o2p<QEventLoopPrivate>(loop), Type::EventLoop}
 {
 
 }
@@ -407,7 +392,7 @@ QEventLoopLocker::QEventLoopLocker(QEventLoop *loop)
     \sa QThread::quit()
  */
 QEventLoopLocker::QEventLoopLocker(QThread *thread)
-  : d_ptr(new QEventLoopLockerPrivate(static_cast<QThreadPrivate*>(QObjectPrivate::get(thread))))
+    : QEventLoopLocker{o2p<QThreadPrivate>(thread), Type::Thread}
 {
 
 }
@@ -421,6 +406,15 @@ QEventLoopLocker::~QEventLoopLocker()
     delete d_ptr;
 }
 
+/*!
+    \internal
+*/
+QEventLoopLocker::QEventLoopLocker(void *ptr, Type t) noexcept
+    : d_ptr(new QEventLoopLockerPrivate{ptr, t})
+{
+    visit([](auto p) { p->ref(); });
+}
+
 /*!
     \internal
 */
diff --git a/src/corelib/kernel/qeventloop.h b/src/corelib/kernel/qeventloop.h
index 265ec76047..becabe2b14 100644
--- a/src/corelib/kernel/qeventloop.h
+++ b/src/corelib/kernel/qeventloop.h
@@ -63,11 +63,18 @@ public:
 
 private:
     Q_DISABLE_COPY(QEventLoopLocker)
+    friend class QEventLoopLockerPrivate;
 
     //
     // Private implementation details.
     // Do not call from public inline API!
     //
+    enum class Type : quintptr {
+        EventLoop,
+        Thread,
+        Application,
+    };
+    explicit QEventLoopLocker(void *ptr, Type t) noexcept;
     QEventLoopLockerPrivate *d_ptr;
     template <typename Func>
     void visit(Func func) const;