qvolatile_p.h

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// Copyright (C) 2021 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com>
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#ifndef QVOLATILE_P_H
#define QVOLATILE_P_H
 
//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists for the convenience
// of a number of Qt sources files.  This header file may change from
// version to version without notice, or even be removed.
//
// We mean it.
//
 
#include <QtCore/private/qglobal_p.h>
 
QT_BEGIN_NAMESPACE
 
namespace QtPrivate {
template <typename T>
using if_volatile = std::enable_if_t<std::is_volatile_v<T>, bool>;
 
//
// C++20-deprecated volatile compound operations, rewritten as separated operations
//
 
// these functions return `auto`, not `T`, to strip cv-qualifiers without having
// to mention the `volatile` keyword
 
template <typename T, QtPrivate::if_volatile<T> = true>
auto volatilePreIncrement(T &x) {
    auto y = x;
    ++y;
    x = y;
    return y;
}
 
template <typename T, QtPrivate::if_volatile<T> = true>
auto volatilePreDecrement(T &x)
{
    auto y = x;
    --y;
    x = y;
    return y;
}
} // namespace QtPrivate
 
QT_END_NAMESPACE
 
#endif // QVOLATILE_H