QV4::Heap::SharedArrayBuffer: avoid std::aligned_storage (deprecated in C++23)

... by rolling our own.

Qt 5.15 uses a pointer (additional indirection), not aligned_storage,
so isn't affected.

References:
- https://github.com/cplusplus/papers/issues/197
- https://wg21.link/p1413

Manual conflict resolutions:
- adapted to different member names and private/public access in the
  6.2 class vis-a-vis the 6.4+ version.

Task-number: QTBUG-99122
Change-Id: Ia116dc11336901a19fc227fb68ac266c1bfbbcb1
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit 6e9a9ed121ce101d19e015de03b8f1d37fa84041)
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/qml/jsruntime/qv4arraybuffer_p.h b/src/qml/jsruntime/qv4arraybuffer_p.h
index 4b2c1b83da..7e0d642116 100644
--- a/src/qml/jsruntime/qv4arraybuffer_p.h
+++ b/src/qml/jsruntime/qv4arraybuffer_p.h
@@ -72,7 +72,7 @@ struct Q_QML_PRIVATE_EXPORT SharedArrayBuffer : Object {
     void init(size_t length);
     void init(const QByteArray& array);
     void destroy();
-    std::aligned_storage_t<sizeof(QArrayDataPointer<char>), alignof(QArrayDataPointer<char>)> d;
+    struct { alignas(QArrayDataPointer<char>) unsigned char data[sizeof(QArrayDataPointer<char>)]; } d;
     const QArrayDataPointer<char> &data() const { return *reinterpret_cast<const QArrayDataPointer<char> *>(&d); }
     QArrayDataPointer<char> &data()  { return *reinterpret_cast<QArrayDataPointer<char> *>(&d); }
     bool isShared;