Long live QKeyCombination!

C++20 via P1120 is deprecating arithmetic operations between
unrelated enumeration types, and GCC 10 is already complaining.
Hence, these operations might become illegal in C++23 or C++26 at
the latest.

A case of this that affects Qt is in key combinations: a
QKeySequence can be constructed by summing / ORing modifiers and a
key, for instance:

  Qt::CTRL + Qt::Key_A
  Qt::SHIFT | Qt::CTRL | Qt::Key_G (recommended, see below)

The problem is that the modifiers and the key belong to different
enumerations (and there's 2 enumerations for the modifier, and one
for the key).

To solve this: add a dedicated class to represent a combination of
keys, and operators between those enumerations to build instances
of this class.

I would've simply defined operator|, but again docs and pre-existing
code use operator+ as well, so added both to at least tackle simple
cases (modifier + key).

Multiple modifiers create a problem: operator+ between them yields
int, not the corresponding flags type (because operator+ is not
overloaded for this use case):

  Qt::CTRL + Qt::SHIFT + Qt::Key_A
  \__________________/      /
          int              /
           \______________/
                  int

Not only this loses track of the datatypes involved, but it would
also then "add" the key (with NO warnings, now its int + enum, so
it's not mixing enums!) and yielding int again.

I don't want to special-case this; the point of the class is
that int is the wrong datatype. Everything works just fine when
using operator| instead:

  Qt::CTRL | Qt::SHIFT | Qt::Key_A
  \__________________/      /
      Qt::Modifiers        /
           \______________/
            QKeyCombination

So I'm defining operator+ so that the simple cases still work,
but also deprecating it.

Port some code around Qt to the new class. In certain cases,
it's a huge win for clarity. In some others, I've just added
the necessary casts to make it still compile without warnings,
without attempting refactorings.

[ChangeLog][QtCore][QKeyCombination] New class to represent
a combination of a key and zero or more modifiers, to be used
when defining shortcuts or similar.

[ChangeLog][Potentially Source-Incompatible Changes] A keyboard
modifier (such as Qt::CTRL, Qt::AltModifier, etc.) should be
combined with a key (such as Qt::Key_A, Qt::Key_F1, etc.) by using
operator|, not operator+.  The result is now an object of type
QKeyCombination, that stores the key and the modifiers.

Change-Id: I657a3a328232f059023fff69c5031ee31cc91dd6
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

35 files changed, 813 insertions, 67 deletions

diff --git a/examples/widgets/desktop/screenshot/screenshot.cpp b/examples/widgets/desktop/screenshot/screenshot.cpp
index af344db1d2..522b1123b5 100644
--- a/examples/widgets/desktop/screenshot/screenshot.cpp
+++ b/examples/widgets/desktop/screenshot/screenshot.cpp
@@ -90,7 +90,7 @@ Screenshot::Screenshot()
     connect(saveScreenshotButton, &QPushButton::clicked, this, &Screenshot::saveScreenshot);
     buttonsLayout->addWidget(saveScreenshotButton);
     QPushButton *quitScreenshotButton = new QPushButton(tr("Quit"), this);
-    quitScreenshotButton->setShortcut(Qt::CTRL + Qt::Key_Q);
+    quitScreenshotButton->setShortcut(Qt::CTRL | Qt::Key_Q);
     connect(quitScreenshotButton, &QPushButton::clicked, this, &QWidget::close);
     buttonsLayout->addWidget(quitScreenshotButton);
     buttonsLayout->addStretch();
diff --git a/examples/widgets/itemviews/storageview/main.cpp b/examples/widgets/itemviews/storageview/main.cpp
index 8f23a4820a..fe916b039d 100644
--- a/examples/widgets/itemviews/storageview/main.cpp
+++ b/examples/widgets/itemviews/storageview/main.cpp
@@ -66,7 +66,7 @@ int main(int argc, char *argv[])
 
     StorageModel *model = new StorageModel(&view);
     model->refresh();
-    QShortcut *refreshShortcut = new QShortcut(Qt::CTRL + Qt::Key_R, &view);
+    QShortcut *refreshShortcut = new QShortcut(Qt::CTRL | Qt::Key_R, &view);
     QObject::connect(refreshShortcut, &QShortcut::activated, model, &StorageModel::refresh);
     view.setModel(model);
 
diff --git a/examples/widgets/richtext/textedit/textedit.cpp b/examples/widgets/richtext/textedit/textedit.cpp
index 9504c8769d..74b8e1c2b4 100644
--- a/examples/widgets/richtext/textedit/textedit.cpp
+++ b/examples/widgets/richtext/textedit/textedit.cpp
@@ -209,14 +209,14 @@ void TextEdit::setupFileActions()
     const QIcon exportPdfIcon = QIcon::fromTheme("exportpdf", QIcon(rsrcPath + "/exportpdf.png"));
     a = menu->addAction(exportPdfIcon, tr("&Export PDF..."), this, &TextEdit::filePrintPdf);
     a->setPriority(QAction::LowPriority);
-    a->setShortcut(Qt::CTRL + Qt::Key_D);
+    a->setShortcut(Qt::CTRL | Qt::Key_D);
     tb->addAction(a);
 
     menu->addSeparator();
 #endif
 
     a = menu->addAction(tr("&Quit"), this, &QWidget::close);
-    a->setShortcut(Qt::CTRL + Qt::Key_Q);
+    a->setShortcut(Qt::CTRL | Qt::Key_Q);
 }
 
 void TextEdit::setupEditActions()
@@ -266,7 +266,7 @@ void TextEdit::setupTextActions()
 
     const QIcon boldIcon = QIcon::fromTheme("format-text-bold", QIcon(rsrcPath + "/textbold.png"));
     actionTextBold = menu->addAction(boldIcon, tr("&Bold"), this, &TextEdit::textBold);
-    actionTextBold->setShortcut(Qt::CTRL + Qt::Key_B);
+    actionTextBold->setShortcut(Qt::CTRL | Qt::Key_B);
     actionTextBold->setPriority(QAction::LowPriority);
     QFont bold;
     bold.setBold(true);
@@ -277,7 +277,7 @@ void TextEdit::setupTextActions()
     const QIcon italicIcon = QIcon::fromTheme("format-text-italic", QIcon(rsrcPath + "/textitalic.png"));
     actionTextItalic = menu->addAction(italicIcon, tr("&Italic"), this, &TextEdit::textItalic);
     actionTextItalic->setPriority(QAction::LowPriority);
-    actionTextItalic->setShortcut(Qt::CTRL + Qt::Key_I);
+    actionTextItalic->setShortcut(Qt::CTRL | Qt::Key_I);
     QFont italic;
     italic.setItalic(true);
     actionTextItalic->setFont(italic);
@@ -286,7 +286,7 @@ void TextEdit::setupTextActions()
 
     const QIcon underlineIcon = QIcon::fromTheme("format-text-underline", QIcon(rsrcPath + "/textunder.png"));
     actionTextUnderline = menu->addAction(underlineIcon, tr("&Underline"), this, &TextEdit::textUnderline);
-    actionTextUnderline->setShortcut(Qt::CTRL + Qt::Key_U);
+    actionTextUnderline->setShortcut(Qt::CTRL | Qt::Key_U);
     actionTextUnderline->setPriority(QAction::LowPriority);
     QFont underline;
     underline.setUnderline(true);
@@ -298,31 +298,31 @@ void TextEdit::setupTextActions()
 
     const QIcon leftIcon = QIcon::fromTheme("format-justify-left", QIcon(rsrcPath + "/textleft.png"));
     actionAlignLeft = new QAction(leftIcon, tr("&Left"), this);
-    actionAlignLeft->setShortcut(Qt::CTRL + Qt::Key_L);
+    actionAlignLeft->setShortcut(Qt::CTRL | Qt::Key_L);
     actionAlignLeft->setCheckable(true);
     actionAlignLeft->setPriority(QAction::LowPriority);
     const QIcon centerIcon = QIcon::fromTheme("format-justify-center", QIcon(rsrcPath + "/textcenter.png"));
     actionAlignCenter = new QAction(centerIcon, tr("C&enter"), this);
-    actionAlignCenter->setShortcut(Qt::CTRL + Qt::Key_E);
+    actionAlignCenter->setShortcut(Qt::CTRL | Qt::Key_E);
     actionAlignCenter->setCheckable(true);
     actionAlignCenter->setPriority(QAction::LowPriority);
     const QIcon rightIcon = QIcon::fromTheme("format-justify-right", QIcon(rsrcPath + "/textright.png"));
     actionAlignRight = new QAction(rightIcon, tr("&Right"), this);
-    actionAlignRight->setShortcut(Qt::CTRL + Qt::Key_R);
+    actionAlignRight->setShortcut(Qt::CTRL | Qt::Key_R);
     actionAlignRight->setCheckable(true);
     actionAlignRight->setPriority(QAction::LowPriority);
     const QIcon fillIcon = QIcon::fromTheme("format-justify-fill", QIcon(rsrcPath + "/textjustify.png"));
     actionAlignJustify = new QAction(fillIcon, tr("&Justify"), this);
-    actionAlignJustify->setShortcut(Qt::CTRL + Qt::Key_J);
+    actionAlignJustify->setShortcut(Qt::CTRL | Qt::Key_J);
     actionAlignJustify->setCheckable(true);
     actionAlignJustify->setPriority(QAction::LowPriority);
     const QIcon indentMoreIcon = QIcon::fromTheme("format-indent-more", QIcon(rsrcPath + "/format-indent-more.png"));
     actionIndentMore = menu->addAction(indentMoreIcon, tr("&Indent"), this, &TextEdit::indent);
-    actionIndentMore->setShortcut(Qt::CTRL + Qt::Key_BracketRight);
+    actionIndentMore->setShortcut(Qt::CTRL | Qt::Key_BracketRight);
     actionIndentMore->setPriority(QAction::LowPriority);
     const QIcon indentLessIcon = QIcon::fromTheme("format-indent-less", QIcon(rsrcPath + "/format-indent-less.png"));
     actionIndentLess = menu->addAction(indentLessIcon, tr("&Unindent"), this, &TextEdit::unindent);
-    actionIndentLess->setShortcut(Qt::CTRL + Qt::Key_BracketLeft);
+    actionIndentLess->setShortcut(Qt::CTRL | Qt::Key_BracketLeft);
     actionIndentLess->setPriority(QAction::LowPriority);
 
     // Make sure the alignLeft  is always left of the alignRight
@@ -358,7 +358,7 @@ void TextEdit::setupTextActions()
 
     const QIcon checkboxIcon = QIcon::fromTheme("status-checkbox-checked", QIcon(rsrcPath + "/checkbox-checked.png"));
     actionToggleCheckState = menu->addAction(checkboxIcon, tr("Chec&ked"), this, &TextEdit::setChecked);
-    actionToggleCheckState->setShortcut(Qt::CTRL + Qt::Key_K);
+    actionToggleCheckState->setShortcut(Qt::CTRL | Qt::Key_K);
     actionToggleCheckState->setCheckable(true);
     actionToggleCheckState->setPriority(QAction::LowPriority);
     tb->addAction(actionToggleCheckState);
diff --git a/src/corelib/global/qnamespace.h b/src/corelib/global/qnamespace.h
index a531bc627b..0c4b4fc8bf 100644
--- a/src/corelib/global/qnamespace.h
+++ b/src/corelib/global/qnamespace.h
@@ -1,6 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2020 The Qt Company Ltd.
+** Copyright (C) 2020 Klaralvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -1094,6 +1095,8 @@ namespace Qt {
         ALT           = Qt::AltModifier,
         MODIFIER_MASK = KeyboardModifierMask,
     };
+    Q_DECLARE_FLAGS(Modifiers, Modifier)
+    Q_DECLARE_OPERATORS_FOR_FLAGS(Modifiers)
 
     enum ArrowType {
         NoArrow,
@@ -1785,6 +1788,9 @@ namespace Qt {
     Q_ENUM_NS(SortOrder)
     Q_ENUM_NS(CaseSensitivity)
     Q_FLAG_NS(MatchFlags)
+    Q_ENUM_NS(Modifier)
+    Q_FLAG_NS(Modifiers)
+    Q_ENUM_NS(KeyboardModifier)
     Q_FLAG_NS(KeyboardModifiers)
     Q_FLAG_NS(MouseButtons)
     Q_ENUM_NS(WindowType)
@@ -1863,6 +1869,156 @@ public:
     static bool activateCallbacks(Callback, void **);
 };
 
+class QKeyCombination
+{
+    int combination;
+
+public:
+    constexpr /* implicit */ QKeyCombination(Qt::Key key = Qt::Key_unknown) noexcept
+        : combination(int(key))
+    {}
+
+    constexpr explicit QKeyCombination(Qt::Modifiers modifiers, Qt::Key key = Qt::Key_unknown) noexcept
+        : combination(int(modifiers) | int(key))
+    {}
+
+    constexpr explicit QKeyCombination(Qt::KeyboardModifiers modifiers, Qt::Key key = Qt::Key_unknown) noexcept
+        : combination(int(modifiers) | int(key))
+    {}
+
+    constexpr Qt::KeyboardModifiers keyboardModifiers() const noexcept
+    {
+        return Qt::KeyboardModifiers(combination & Qt::KeyboardModifierMask);
+    }
+
+    constexpr Qt::Key key() const noexcept
+    {
+        return Qt::Key(combination & ~Qt::KeyboardModifierMask);
+    }
+
+    static constexpr QKeyCombination fromCombined(int combined)
+    {
+        QKeyCombination result;
+        result.combination = combined;
+        return result;
+    }
+
+    constexpr int toCombined() const noexcept
+    {
+        return combination;
+    }
+
+#if QT_DEPRECATED_SINCE(6, 0)
+    QT_DEPRECATED_VERSION_X(6, 0, "Use QKeyCombination instead of int")
+    constexpr /* implicit */ operator int() const noexcept
+    {
+        return combination;
+    }
+#endif
+
+    friend constexpr bool operator==(QKeyCombination lhs, QKeyCombination rhs) noexcept
+    {
+        return lhs.combination == rhs.combination;
+    }
+
+    friend constexpr bool operator!=(QKeyCombination lhs, QKeyCombination rhs) noexcept
+    {
+        return lhs.combination != rhs.combination;
+    }
+};
+
+Q_DECLARE_TYPEINFO(QKeyCombination, Q_MOVABLE_TYPE);
+
+constexpr QKeyCombination operator|(Qt::Modifier modifier, Qt::Key key) noexcept
+{
+    return QKeyCombination(modifier, key);
+}
+
+constexpr QKeyCombination operator|(Qt::Modifiers modifiers, Qt::Key key) noexcept
+{
+    return QKeyCombination(modifiers, key);
+}
+
+constexpr QKeyCombination operator|(Qt::KeyboardModifier modifier, Qt::Key key) noexcept
+{
+    return QKeyCombination(modifier, key);
+}
+
+constexpr QKeyCombination operator|(Qt::KeyboardModifiers modifiers, Qt::Key key) noexcept
+{
+    return QKeyCombination(modifiers, key);
+}
+
+constexpr QKeyCombination operator|(Qt::Key key, Qt::Modifier modifier) noexcept
+{
+    return QKeyCombination(modifier, key);
+}
+
+constexpr QKeyCombination operator|(Qt::Key key, Qt::Modifiers modifiers) noexcept
+{
+    return QKeyCombination(modifiers, key);
+}
+
+constexpr QKeyCombination operator|(Qt::Key key, Qt::KeyboardModifier modifier) noexcept
+{
+    return QKeyCombination(modifier, key);
+}
+
+constexpr QKeyCombination operator|(Qt::Key key, Qt::KeyboardModifiers modifiers) noexcept
+{
+    return QKeyCombination(modifiers, key);
+}
+
+#if QT_DEPRECATED_SINCE(6, 0)
+QT_DEPRECATED_VERSION_X(6, 0, "Use operator| instead")
+constexpr QKeyCombination operator+(Qt::Modifier modifier, Qt::Key key) noexcept
+{
+    return QKeyCombination(modifier, key);
+}
+
+QT_DEPRECATED_VERSION_X(6, 0, "Use operator| instead")
+constexpr QKeyCombination operator+(Qt::Modifiers modifiers, Qt::Key key) noexcept
+{
+    return QKeyCombination(modifiers, key);
+}
+
+QT_DEPRECATED_VERSION_X(6, 0, "Use operator| instead")
+constexpr QKeyCombination operator+(Qt::KeyboardModifier modifier, Qt::Key key) noexcept
+{
+    return QKeyCombination(modifier, key);
+}
+
+QT_DEPRECATED_VERSION_X(6, 0, "Use operator| instead")
+constexpr QKeyCombination operator+(Qt::KeyboardModifiers modifiers, Qt::Key key) noexcept
+{
+    return QKeyCombination(modifiers, key);
+}
+
+QT_DEPRECATED_VERSION_X(6, 0, "Use operator| instead")
+constexpr QKeyCombination operator+(Qt::Key key, Qt::Modifier modifier) noexcept
+{
+    return QKeyCombination(modifier, key);
+}
+
+QT_DEPRECATED_VERSION_X(6, 0, "Use operator| instead")
+constexpr QKeyCombination operator+(Qt::Key key, Qt::Modifiers modifiers) noexcept
+{
+    return QKeyCombination(modifiers, key);
+}
+
+QT_DEPRECATED_VERSION_X(6, 0, "Use operator| instead")
+constexpr QKeyCombination operator+(Qt::Key key, Qt::KeyboardModifier modifier) noexcept
+{
+    return QKeyCombination(modifier, key);
+}
+
+QT_DEPRECATED_VERSION_X(6, 0, "Use operator| instead")
+constexpr QKeyCombination operator+(Qt::Key key, Qt::KeyboardModifiers modifiers) noexcept
+{
+    return QKeyCombination(modifiers, key);
+}
+#endif
+
 QT_END_NAMESPACE
 
 #endif // QNAMESPACE_H
diff --git a/src/corelib/global/qnamespace.qdoc b/src/corelib/global/qnamespace.qdoc
index 95a73c4439..b5d44cb1cb 100644
--- a/src/corelib/global/qnamespace.qdoc
+++ b/src/corelib/global/qnamespace.qdoc
@@ -1,6 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2020 The Qt Company Ltd.
+** Copyright (C) 2020 Klaralvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the documentation of the Qt Toolkit.
@@ -3246,3 +3247,201 @@
   \sa QLabel::picture()
   \sa QLabel::pixmap()
 */
+
+/*!
+  \class QKeyCombination
+  \inmodule QtCore
+  \since 6.0
+  \brief The QKeyCombination class stores a combination of a key with optional modifiers.
+
+  The QKeyCombination class can be used to represent a combination of a key
+  with zero or more keyboard modifiers.
+
+  \sa QKeySequence
+*/
+
+/*!
+  \fn QKeyCombination::QKeyCombination(Qt::Key key = Qt::Key_unknown) noexcept
+
+  Constructs a QKeyCombination object that represents the key \a key
+  and no modifiers.
+
+  \sa key()
+*/
+
+/*!
+  \fn QKeyCombination::QKeyCombination(Qt::Modifiers modifiers, Qt::Key key = Qt::Key_unknown) noexcept
+
+  Constructs a QKeyCombination object that represents the combination
+  of \a key with the modifiers \a modifiers.
+
+  \sa key(), keyboardModifiers()
+*/
+
+/*!
+  \fn QKeyCombination::QKeyCombination(Qt::KeyboardModifiers modifiers, Qt::Key key = Qt::Key_unknown) noexcept
+
+  Constructs a QKeyCombination object that represents the combination
+  of \a key with the modifiers \a modifiers.
+
+  \sa key(), keyboardModifiers()
+*/
+
+/*!
+  \fn Qt::KeyboardModifiers QKeyCombination::keyboardModifiers() const noexcept
+
+  Returns the keyboard modifiers represented by this QKeyCombination object.
+
+  \sa key()
+*/
+
+/*!
+  \fn Qt::Key QKeyCombination::key() const noexcept
+
+  Returns the key represented by this QKeyCombination object.
+
+  \sa keyboardModifiers()
+*/
+
+/*!
+  \fn QKeyCombination QKeyCombination::fromCombined(int combined)
+
+  Constructs a QKeyCombination object by extracting the key and the
+  modifiers out of \a combined, which must be the result of a bitwise
+  OR between a value of type Qt::Key and value of type
+  Qt::KeyboardModifiers. toCombined() can be used in order to produce
+  valid values for \a combined.
+
+  \sa toCombined()
+*/
+
+/*!
+  \fn int QKeyCombination::toCombined() const noexcept
+
+  Returns an integer value obtained by applying a bitwise OR between
+  the values of key() and keyboardModifiers() represented
+  by this object. A QKeyCombination object can be created from the
+  returned integer value by using fromCombined().
+
+  \sa fromCombined(), key(), keyboardModifiers()
+*/
+
+#if QT_DEPRECATED_SINCE(6, 0)
+/*!
+  \fn QKeyCombination::operator int() const noexcept
+  \obsolete
+
+  Use toCombined() instead.
+*/
+#endif
+
+/*!
+  \fn bool operator==(QKeyCombination lhs, QKeyCombination rhs) noexcept
+  \relates QKeyCombination
+
+  Returns \c true if \a lhs and \a rhs have the same combination
+  of key and modifiers, and \c false otherwise.
+*/
+
+/*!
+  \fn bool operator!=(QKeyCombination lhs, QKeyCombination rhs) noexcept
+  \relates QKeyCombination
+
+  Returns \c true if \a lhs and \a rhs have different combinations
+  of key and modifiers, otherwise \c false.
+*/
+
+/*!
+  \fn QKeyCombination operator|(Qt::Modifier modifier, Qt::Key key) noexcept
+  \fn QKeyCombination operator|(Qt::KeyboardModifier modifier, Qt::Key key) noexcept
+  \fn QKeyCombination operator|(Qt::Key key, Qt::Modifier modifier) noexcept
+  \fn QKeyCombination operator|(Qt::Key key, Qt::KeyboardModifier modifier) noexcept
+
+  \relates QKeyCombination
+
+  Returns a QKeyCombination object that represents the combination
+  of \a key with the modifier \a modifier.
+*/
+
+/*!
+  \fn QKeyCombination operator|(Qt::Modifiers modifiers, Qt::Key key) noexcept
+  \fn QKeyCombination operator|(Qt::KeyboardModifiers modifiers, Qt::Key key) noexcept
+  \fn QKeyCombination operator|(Qt::Key key, Qt::Modifiers modifiers) noexcept
+  \fn QKeyCombination operator|(Qt::Key key, Qt::KeyboardModifiers modifiers) noexcept
+
+  \relates QKeyCombination
+
+  Returns a QKeyCombination object that represents the combination
+  of \a key with the modifiers \a modifiers.
+*/
+
+/*!
+  \fn QKeyCombination operator+(Qt::Modifier modifier, Qt::Key key) noexcept
+  \fn QKeyCombination operator+(Qt::KeyboardModifier modifier, Qt::Key key) noexcept
+  \fn QKeyCombination operator+(Qt::Key key, Qt::Modifier modifier) noexcept
+  \fn QKeyCombination operator+(Qt::Key key, Qt::KeyboardModifier modifier) noexcept
+
+  \relates QKeyCombination
+  \obsolete
+
+  Use operator| instead.
+
+  Returns a QKeyCombination object that represents the combination
+  of \a key with the modifier \a modifier.
+*/
+
+/*!
+  \fn QKeyCombination operator+(Qt::Modifiers modifiers, Qt::Key key) noexcept
+  \fn QKeyCombination operator+(Qt::KeyboardModifiers modifiers, Qt::Key key) noexcept
+  \fn QKeyCombination operator+(Qt::Key key, Qt::Modifiers modifiers) noexcept
+  \fn QKeyCombination operator+(Qt::Key key, Qt::KeyboardModifiers modifiers) noexcept
+
+  \relates QKeyCombination
+  \obsolete
+
+  Use operator| instead.
+
+  Returns a QKeyCombination object that represents the combination
+  of \a key with the modifiers \a modifiers.
+*/
+
+/*!
+  \fn size_t qHash(QKeyCombination key, size_t seed = 0) noexcept
+  \relates QKeyCombination
+
+  Returns the hash value for the \a key, using \a seed to seed the calculation.
+*/
+
+#ifndef QT_NO_DEBUG_STREAM
+/*!
+  \fn QDebug operator<<(QDebug debug, QKeyCombination combination)
+  \relates QKeyCombination
+
+  Writes the combination \a combination into the debug object \a debug for
+  debugging purposes.
+
+  \sa {Debugging Techniques}
+*/
+#endif
+
+#ifndef QT_NO_DATASTREAM
+/*!
+  \fn QDataStream &operator<<(QDataStream &out, QKeyCombination combination)
+  \relates QKeyCombination
+
+  Writes the combination \a combination into the stream \a out.
+  Returns \a out.
+
+  \sa {Serializing Qt Data Types}
+*/
+
+/*!
+  \fn QDataStream &operator>>(QDataStream &in, QKeyCombination &combination)
+  \relates QKeyCombination
+
+  Reads the combination \a combination from the stream \a in.
+  Returns \a in.
+
+  \sa {Serializing Qt Data Types}
+*/
+#endif
diff --git a/src/corelib/io/qdebug.h b/src/corelib/io/qdebug.h
index 2463095743..b3787f9e78 100644
--- a/src/corelib/io/qdebug.h
+++ b/src/corelib/io/qdebug.h
@@ -446,6 +446,17 @@ inline QDebug operator<<(QDebug debug, const QFlags<T> &flags)
     return qt_QMetaEnum_flagDebugOperator_helper(debug, flags);
 }
 
+inline QDebug operator<<(QDebug debug, QKeyCombination combination)
+{
+    QDebugStateSaver saver(debug);
+    debug.nospace() << "QKeyCombination("
+                    << combination.keyboardModifiers()
+                    << ", "
+                    << combination.key()
+                    << ")";
+    return debug;
+}
+
 #ifdef Q_OS_MAC
 
 // We provide QDebug stream operators for commonly used Core Foundation
diff --git a/src/corelib/serialization/qdatastream.h b/src/corelib/serialization/qdatastream.h
index 19188c3d91..32ccf7d6cc 100644
--- a/src/corelib/serialization/qdatastream.h
+++ b/src/corelib/serialization/qdatastream.h
@@ -43,6 +43,7 @@
 #include <QtCore/qscopedpointer.h>
 #include <QtCore/qiodevicebase.h>
 #include <QtCore/qcontainerfwd.h>
+#include <QtCore/qnamespace.h>
 
 #ifdef Status
 #error qdatastream.h must be included before any header file that defines Status
@@ -510,6 +511,19 @@ inline QDataStreamIfHasOStreamOperators<T1, T2> operator<<(QDataStream& s, const
 }
 #endif
 
+inline QDataStream &operator>>(QDataStream &s, QKeyCombination &combination)
+{
+    int combined;
+    s >> combined;
+    combination = QKeyCombination::fromCombined(combined);
+    return s;
+}
+
+inline QDataStream &operator<<(QDataStream &s, QKeyCombination combination)
+{
+    return s << combination.toCombined();
+}
+
 #endif // QT_NO_DATASTREAM
 
 QT_END_NAMESPACE
diff --git a/src/corelib/tools/qhashfunctions.h b/src/corelib/tools/qhashfunctions.h
index 716b81e186..94c6e13b1c 100644
--- a/src/corelib/tools/qhashfunctions.h
+++ b/src/corelib/tools/qhashfunctions.h
@@ -162,6 +162,8 @@ inline Q_DECL_PURE_FUNCTION size_t qHash(const QString &key, size_t seed = 0) no
 #endif
 Q_CORE_EXPORT Q_DECL_PURE_FUNCTION size_t qHash(const QBitArray &key, size_t seed = 0) noexcept;
 Q_CORE_EXPORT Q_DECL_PURE_FUNCTION size_t qHash(QLatin1String key, size_t seed = 0) noexcept;
+Q_DECL_CONST_FUNCTION constexpr inline size_t qHash(QKeyCombination key, size_t seed = 0) noexcept
+{ return qHash(key.toCombined(), seed); }
 Q_CORE_EXPORT Q_DECL_PURE_FUNCTION uint qt_hash(QStringView key, uint chained = 0) noexcept;
 
 template<typename T> inline size_t qHash(const T &t, size_t seed)
diff --git a/src/gui/doc/snippets/code/src_gui_kernel_qkeysequence.cpp b/src/gui/doc/snippets/code/src_gui_kernel_qkeysequence.cpp
index 2994bb60cf..4be214ad64 100644
--- a/src/gui/doc/snippets/code/src_gui_kernel_qkeysequence.cpp
+++ b/src/gui/doc/snippets/code/src_gui_kernel_qkeysequence.cpp
@@ -62,13 +62,15 @@ struct Wrapper : public QWidget
 QKeySequence(QKeySequence::Print);
 QKeySequence(tr("Ctrl+P"));
 QKeySequence(tr("Ctrl+p"));
-QKeySequence(Qt::CTRL + Qt::Key_P);
+QKeySequence(Qt::CTRL | Qt::Key_P);
+QKeySequence(Qt::CTRL + Qt::Key_P); // deprecated
 //! [0]
 
 
 //! [1]
 QKeySequence(tr("Ctrl+X, Ctrl+C"));
-QKeySequence(Qt::CTRL + Qt::Key_X, Qt::CTRL + Qt::Key_C);
+QKeySequence(Qt::CTRL | Qt::Key_X, Qt::CTRL | Qt::Key_C);
+QKeySequence(Qt::CTRL + Qt::Key_X, Qt::CTRL + Qt::Key_C); // deprecated
 //! [1]
 
 */ // Wrap non-compilable code snippet
diff --git a/src/gui/doc/snippets/code/src_gui_kernel_qshortcut.cpp b/src/gui/doc/snippets/code/src_gui_kernel_qshortcut.cpp
index bac264fcfc..370afd0679 100644
--- a/src/gui/doc/snippets/code/src_gui_kernel_qshortcut.cpp
+++ b/src/gui/doc/snippets/code/src_gui_kernel_qshortcut.cpp
@@ -60,6 +60,6 @@ setKey(QKeySequence());     // no signal emitted
 setKey(0x3b1);              // Greek letter alpha
 setKey(Qt::Key_D);              // 'd', e.g. to delete
 setKey('q');                // 'q', e.g. to quit
-setKey(Qt::CTRL + Qt::Key_P);       // Ctrl+P, e.g. to print document
+setKey(Qt::CTRL | Qt::Key_P);       // Ctrl+P, e.g. to print document
 setKey("Ctrl+P");           // Ctrl+P, e.g. to print document
 //! [1]
diff --git a/src/gui/kernel/qevent.cpp b/src/gui/kernel/qevent.cpp
index 1a6a43a4cb..b4880eff53 100644
--- a/src/gui/kernel/qevent.cpp
+++ b/src/gui/kernel/qevent.cpp
@@ -1285,6 +1285,15 @@ Qt::KeyboardModifiers QKeyEvent::modifiers() const
     return QInputEvent::modifiers();
 }
 
+/*!
+    \fn QKeyCombination QKeyEvent::keyCombination() const
+
+    Returns a QKeyCombination object containing both the key() and
+    the modifiers() carried by this event.
+
+    \since 6.0
+*/
+
 #if QT_CONFIG(shortcut)
 /*!
     \fn bool QKeyEvent::matches(QKeySequence::StandardKey key) const
diff --git a/src/gui/kernel/qevent.h b/src/gui/kernel/qevent.h
index 2c0325296d..c8402b6632 100644
--- a/src/gui/kernel/qevent.h
+++ b/src/gui/kernel/qevent.h
@@ -480,6 +480,10 @@ public:
     bool matches(QKeySequence::StandardKey key) const;
 #endif
     Qt::KeyboardModifiers modifiers() const;
+    QKeyCombination keyCombination() const
+    {
+        return QKeyCombination(modifiers(), Qt::Key(m_key));
+    }
     inline QString text() const { return m_text; }
     inline bool isAutoRepeat() const { return m_autoRepeat; }
     inline int count() const { return int(m_count); }
diff --git a/src/gui/kernel/qguivariant.cpp b/src/gui/kernel/qguivariant.cpp
index ebb180dc8e..1af0692173 100644
--- a/src/gui/kernel/qguivariant.cpp
+++ b/src/gui/kernel/qguivariant.cpp
@@ -99,7 +99,6 @@ struct GuiTypesFilter {
     };
 };
 
-
 static const struct : QMetaTypeModuleHelper
 {
 #define QT_IMPL_METATYPEINTERFACE_GUI_TYPES(MetaTypeName, MetaTypeId, RealName) \
@@ -146,7 +145,7 @@ static const struct : QMetaTypeModuleHelper
         );
         QMETATYPE_CONVERTER(QKeySequence, QString, result = source; return true;);
         QMETATYPE_CONVERTER(Int, QKeySequence,
-            result = source.isEmpty() ? 0 : source[0];
+            result = source.isEmpty() ? 0 : source[0].toCombined();
             return true;
         );
         QMETATYPE_CONVERTER(QKeySequence, Int, result = source; return true;);
diff --git a/src/gui/kernel/qkeymapper.cpp b/src/gui/kernel/qkeymapper.cpp
index f0ea66dc79..89eacc944a 100644
--- a/src/gui/kernel/qkeymapper.cpp
+++ b/src/gui/kernel/qkeymapper.cpp
@@ -71,17 +71,20 @@ QKeyMapper::~QKeyMapper()
 {
 }
 
-QList<int> QKeyMapper::possibleKeys(QKeyEvent *e)
+static QList<int> extractKeyFromEvent(QKeyEvent *e)
 {
     QList<int> result;
+    if (e->key() && (e->key() != Qt::Key_unknown))
+        result << e->keyCombination().toCombined();
+    else if (!e->text().isEmpty())
+        result << int(e->text().at(0).unicode() + (int)e->modifiers());
+    return result;
+}
 
-    if (!e->nativeScanCode()) {
-        if (e->key() && (e->key() != Qt::Key_unknown))
-            result << int(e->key() + e->modifiers());
-        else if (!e->text().isEmpty())
-            result << int(e->text().at(0).unicode() + e->modifiers());
-        return result;
-    }
+QList<int> QKeyMapper::possibleKeys(QKeyEvent *e)
+{
+    if (!e->nativeScanCode())
+        return extractKeyFromEvent(e);
 
     return instance()->d_func()->possibleKeys(e);
 }
@@ -132,11 +135,7 @@ QList<int> QKeyMapperPrivate::possibleKeys(QKeyEvent *e)
     if (!result.isEmpty())
         return result;
 
-    if (e->key() && (e->key() != Qt::Key_unknown))
-        result << int(e->key() + e->modifiers());
-    else if (!e->text().isEmpty())
-        result << int(e->text().at(0).unicode() + e->modifiers());
-    return result;
+    return extractKeyFromEvent(e);
 }
 
 QT_END_NAMESPACE
diff --git a/src/gui/kernel/qkeysequence.cpp b/src/gui/kernel/qkeysequence.cpp
index 13e6a058cb..5d52ba139d 100644
--- a/src/gui/kernel/qkeysequence.cpp
+++ b/src/gui/kernel/qkeysequence.cpp
@@ -870,6 +870,17 @@ QKeySequence::QKeySequence(int k1, int k2, int k3, int k4)
 }
 
 /*!
+    Constructs a key sequence with up to 4 keys \a k1, \a k2,
+    \a k3 and \a k4.
+
+    \sa QKeyCombination
+*/
+QKeySequence::QKeySequence(QKeyCombination k1, QKeyCombination k2, QKeyCombination k3, QKeyCombination k4)
+    : QKeySequence(k1.toCombined(), k2.toCombined(), k3.toCombined(), k4.toCombined())
+{
+}
+
+/*!
     Copy constructor. Makes a copy of \a keysequence.
  */
 QKeySequence::QKeySequence(const QKeySequence& keysequence)
@@ -908,11 +919,11 @@ QKeySequence::~QKeySequence()
     delivery.
 */
 
-void QKeySequence::setKey(int key, int index)
+void QKeySequence::setKey(QKeyCombination key, int index)
 {
     Q_ASSERT_X(index >= 0 && index < QKeySequencePrivate::MaxKeyCount, "QKeySequence::setKey", "index out of range");
     qAtomicDetach(d);
-    d->key[index] = key;
+    d->key[index] = key.toCombined();
 }
 
 static_assert(QKeySequencePrivate::MaxKeyCount == 4, "Change docs below");
@@ -967,7 +978,7 @@ QKeySequence QKeySequence::mnemonic(const QString &text)
             if (c.isPrint()) {
                 if (!found) {
                     c = c.toUpper();
-                    ret = QKeySequence(c.unicode() + Qt::ALT);
+                    ret = QKeySequence(QKeyCombination(Qt::ALT, Qt::Key(c.unicode())));
 #ifdef QT_NO_DEBUG
                     return ret;
 #else
@@ -1377,8 +1388,8 @@ QKeySequence::SequenceMatch QKeySequence::matches(const QKeySequence &seq) const
     SequenceMatch match = (userN == seqN ? ExactMatch : PartialMatch);
 
     for (uint i = 0; i < userN; ++i) {
-        int userKey = (*this)[i],
-            sequenceKey = seq[i];
+        QKeyCombination userKey = (*this)[i],
+                    sequenceKey = seq[i];
         if (userKey != sequenceKey)
             return NoMatch;
     }
@@ -1397,10 +1408,10 @@ QKeySequence::operator QVariant() const
     Returns a reference to the element at position \a index in the key
     sequence. This can only be used to read an element.
  */
-int QKeySequence::operator[](uint index) const
+QKeyCombination QKeySequence::operator[](uint index) const
 {
     Q_ASSERT_X(index < QKeySequencePrivate::MaxKeyCount, "QKeySequence::operator[]", "index out of range");
-    return d->key[index];
+    return QKeyCombination::fromCombined(d->key[index]);
 }
 
 
diff --git a/src/gui/kernel/qkeysequence.h b/src/gui/kernel/qkeysequence.h
index 8b7ff12bed..880d0a581a 100644
--- a/src/gui/kernel/qkeysequence.h
+++ b/src/gui/kernel/qkeysequence.h
@@ -155,6 +155,10 @@ public:
     QKeySequence();
     QKeySequence(const QString &key, SequenceFormat format = NativeText);
     QKeySequence(int k1, int k2 = 0, int k3 = 0, int k4 = 0);
+    QKeySequence(QKeyCombination k1,
+                 QKeyCombination k2 = QKeyCombination::fromCombined(0),
+                 QKeyCombination k3 = QKeyCombination::fromCombined(0),
+                 QKeyCombination k4 = QKeyCombination::fromCombined(0));
     QKeySequence(const QKeySequence &ks);
     QKeySequence(StandardKey key);
     ~QKeySequence();
@@ -179,7 +183,7 @@ public:
     static QList<QKeySequence> keyBindings(StandardKey key);
 
     operator QVariant() const;
-    int operator[](uint i) const;
+    QKeyCombination operator[](uint i) const;
     QKeySequence &operator=(const QKeySequence &other);
     QKeySequence &operator=(QKeySequence &&other) noexcept { swap(other); return *this; }
     void swap(QKeySequence &other) noexcept { qSwap(d, other.d); }
@@ -201,7 +205,7 @@ private:
     static QString encodeString(int key);
     int assign(const QString &str);
     int assign(const QString &str, SequenceFormat format);
-    void setKey(int key, int index);
+    void setKey(QKeyCombination key, int index);
 
     QKeySequencePrivate *d;
 
diff --git a/src/gui/kernel/qkeysequence_p.h b/src/gui/kernel/qkeysequence_p.h
index 8c59505561..99d17e98d1 100644
--- a/src/gui/kernel/qkeysequence_p.h
+++ b/src/gui/kernel/qkeysequence_p.h
@@ -64,7 +64,7 @@ struct QKeyBinding
 {
     QKeySequence::StandardKey standardKey;
     uchar priority;
-    uint shortcut;
+    QKeyCombination shortcut;
     uint platform;
 };
 
diff --git a/src/gui/kernel/qplatformtheme.cpp b/src/gui/kernel/qplatformtheme.cpp
index 81c897def7..5de1c98127 100644
--- a/src/gui/kernel/qplatformtheme.cpp
+++ b/src/gui/kernel/qplatformtheme.cpp
@@ -645,7 +645,7 @@ QList<QKeySequence> QPlatformTheme::keyBindings(QKeySequence::StandardKey key) c
         if (!(it->platform & platform))
             continue;
 
-        uint shortcut = it->shortcut;
+        uint shortcut = it->shortcut.toCombined();
 
         if (it->priority > 0)
             list.prepend(QKeySequence(shortcut));
diff --git a/src/gui/kernel/qshortcutmap.cpp b/src/gui/kernel/qshortcutmap.cpp
index 4b6368a749..e79aaacd1a 100644
--- a/src/gui/kernel/qshortcutmap.cpp
+++ b/src/gui/kernel/qshortcutmap.cpp
@@ -543,12 +543,12 @@ void QShortcutMap::createNewSequences(QKeyEvent *e, QList<QKeySequence> &ksl, in
                 curKsl.setKey(curSeq[2], 2);
                 curKsl.setKey(curSeq[3], 3);
             } else {
-                curKsl.setKey(0, 0);
-                curKsl.setKey(0, 1);
-                curKsl.setKey(0, 2);
-                curKsl.setKey(0, 3);
+                curKsl.setKey(QKeyCombination::fromCombined(0), 0);
+                curKsl.setKey(QKeyCombination::fromCombined(0), 1);
+                curKsl.setKey(QKeyCombination::fromCombined(0), 2);
+                curKsl.setKey(QKeyCombination::fromCombined(0), 3);
             }
-            curKsl.setKey(possibleKeys.at(pkNum) & ~ignoredModifiers, index);
+            curKsl.setKey(QKeyCombination::fromCombined(possibleKeys.at(pkNum) & ~ignoredModifiers), index);
         }
     }
 }
@@ -574,8 +574,8 @@ QKeySequence::SequenceMatch QShortcutMap::matches(const QKeySequence &seq1,
                                             : QKeySequence::PartialMatch);
 
     for (uint i = 0; i < userN; ++i) {
-        int userKey = seq1[i],
-            sequenceKey = seq2[i];
+        int userKey = seq1[i].toCombined(),
+            sequenceKey = seq2[i].toCombined();
         if ((userKey & Qt::Key_unknown) == Qt::Key_hyphen)
             userKey = (userKey & Qt::KeyboardModifierMask) | Qt::Key_Minus;
         if ((sequenceKey & Qt::Key_unknown) == Qt::Key_hyphen)
diff --git a/src/gui/platform/unix/dbusmenu/qdbusmenutypes.cpp b/src/gui/platform/unix/dbusmenu/qdbusmenutypes.cpp
index 73ff0aee69..c5bc4a1889 100644
--- a/src/gui/platform/unix/dbusmenu/qdbusmenutypes.cpp
+++ b/src/gui/platform/unix/dbusmenu/qdbusmenutypes.cpp
@@ -241,7 +241,7 @@ QDBusMenuShortcut QDBusMenuItem::convertKeySequence(const QKeySequence &sequence
     QDBusMenuShortcut shortcut;
     for (int i = 0; i < sequence.count(); ++i) {
         QStringList tokens;
-        int key = sequence[i];
+        int key = sequence[i].toCombined();
         if (key & Qt::MetaModifier)
             tokens << QStringLiteral("Super");
         if (key & Qt::ControlModifier)
diff --git a/src/gui/platform/unix/qxkbcommon.cpp b/src/gui/platform/unix/qxkbcommon.cpp
index ff19ebd5d5..71f1cfd24a 100644
--- a/src/gui/platform/unix/qxkbcommon.cpp
+++ b/src/gui/platform/unix/qxkbcommon.cpp
@@ -656,7 +656,7 @@ QList<int> QXkbCommon::possibleKeys(xkb_state *state, const QKeyEvent *event,
 
     int baseQtKey = keysymToQtKey_internal(sym, modifiers, queryState, keycode, superAsMeta, hyperAsMeta);
     if (baseQtKey)
-        result += (baseQtKey + modifiers);
+        result += (baseQtKey + int(modifiers));
 
     xkb_mod_index_t shiftMod = xkb_keymap_mod_get_index(keymap, "Shift");
     xkb_mod_index_t altMod = xkb_keymap_mod_get_index(keymap, "Alt");
@@ -711,7 +711,7 @@ QList<int> QXkbCommon::possibleKeys(xkb_state *state, const QKeyEvent *event,
             if (ambiguous)
                 continue;
 
-            result += (qtKey + mods);
+            result += (qtKey + int(mods));
         }
     }
 
diff --git a/src/testlib/qtestkeyboard.h b/src/testlib/qtestkeyboard.h
index 1882c858c1..deee6da753 100644
--- a/src/testlib/qtestkeyboard.h
+++ b/src/testlib/qtestkeyboard.h
@@ -172,8 +172,8 @@ namespace QTest
     Q_DECL_UNUSED inline static void keySequence(QWindow *window, const QKeySequence &keySequence)
     {
         for (int i = 0; i < keySequence.count(); ++i) {
-            const Qt::Key key = Qt::Key(keySequence[i] & ~Qt::KeyboardModifierMask);
-            const Qt::KeyboardModifiers modifiers = Qt::KeyboardModifiers(keySequence[i] & Qt::KeyboardModifierMask);
+            const Qt::Key key = keySequence[i].key();
+            const Qt::KeyboardModifiers modifiers = keySequence[i].keyboardModifiers();
             keyClick(window, key, modifiers);
         }
     }
@@ -313,8 +313,8 @@ namespace QTest
     inline static void keySequence(QWidget *widget, const QKeySequence &keySequence)
     {
         for (int i = 0; i < keySequence.count(); ++i) {
-            const Qt::Key key = Qt::Key(keySequence[i] & ~Qt::KeyboardModifierMask);
-            const Qt::KeyboardModifiers modifiers = Qt::KeyboardModifiers(keySequence[i] & Qt::KeyboardModifierMask);
+            const Qt::Key key = keySequence[i].key();
+            const Qt::KeyboardModifiers modifiers = keySequence[i].keyboardModifiers();
             keyClick(widget, key, modifiers);
         }
     }
diff --git a/src/widgets/dialogs/qfiledialog.cpp b/src/widgets/dialogs/qfiledialog.cpp
index 81e182c352..c4df58b6aa 100644
--- a/src/widgets/dialogs/qfiledialog.cpp
+++ b/src/widgets/dialogs/qfiledialog.cpp
@@ -3287,7 +3287,7 @@ void QFileDialogPrivate::createMenuActions()
 
     QAction *goHomeAction =  new QAction(q);
 #ifndef QT_NO_SHORTCUT
-    goHomeAction->setShortcut(Qt::CTRL + Qt::Key_H + Qt::SHIFT);
+    goHomeAction->setShortcut(Qt::CTRL | Qt::SHIFT | Qt::Key_H);
 #endif
     QObject::connect(goHomeAction, SIGNAL(triggered()), q, SLOT(_q_goHome()));
     q->addAction(goHomeAction);
diff --git a/src/widgets/dialogs/qmessagebox.cpp b/src/widgets/dialogs/qmessagebox.cpp
index 4183098274..566263f1e0 100644
--- a/src/widgets/dialogs/qmessagebox.cpp
+++ b/src/widgets/dialogs/qmessagebox.cpp
@@ -1522,7 +1522,7 @@ void QMessageBox::keyPressEvent(QKeyEvent *e)
             const QList<QAbstractButton *> buttons = d->buttonBox->buttons();
             for (auto *pb : buttons) {
                 QKeySequence shortcut = pb->shortcut();
-                if (!shortcut.isEmpty() && key == int(shortcut[0] & ~Qt::MODIFIER_MASK)) {
+                if (!shortcut.isEmpty() && key == shortcut[0].key()) {
                     pb->animateClick();
                     return;
                 }
diff --git a/src/widgets/kernel/qwhatsthis.cpp b/src/widgets/kernel/qwhatsthis.cpp
index 7ca50f9dab..b483655a71 100644
--- a/src/widgets/kernel/qwhatsthis.cpp
+++ b/src/widgets/kernel/qwhatsthis.cpp
@@ -510,7 +510,7 @@ QWhatsThisAction::QWhatsThisAction(QObject *parent) : QAction(tr("What's This?")
     setCheckable(true);
     connect(this, SIGNAL(triggered()), this, SLOT(actionTriggered()));
 #ifndef QT_NO_SHORTCUT
-    setShortcut(Qt::ShiftModifier + Qt::Key_F1);
+    setShortcut(Qt::ShiftModifier | Qt::Key_F1);
 #endif
 }
 
diff --git a/src/widgets/widgets/qkeysequenceedit.cpp b/src/widgets/widgets/qkeysequenceedit.cpp
index a38250c195..97ee915037 100644
--- a/src/widgets/widgets/qkeysequenceedit.cpp
+++ b/src/widgets/widgets/qkeysequenceedit.cpp
@@ -63,7 +63,7 @@ void QKeySequenceEditPrivate::init()
     layout->setContentsMargins(0, 0, 0, 0);
     layout->addWidget(lineEdit);
 
-    key[0] = key[1] = key[2] = key[3] = 0;
+    std::fill_n(key, QKeySequencePrivate::MaxKeyCount, QKeyCombination::fromCombined(0));
 
     lineEdit->setFocusProxy(q);
     lineEdit->installEventFilter(q);
@@ -186,7 +186,7 @@ void QKeySequenceEdit::setKeySequence(const QKeySequence &keySequence)
 
     d->keySequence = keySequence;
 
-    d->key[0] = d->key[1] = d->key[2] = d->key[3] = 0;
+    d->key[0] = d->key[1] = d->key[2] = d->key[3] = QKeyCombination::fromCombined(0);
     d->keyNum = keySequence.count();
     for (int i = 0; i < d->keyNum; ++i)
         d->key[i] = keySequence[i];
@@ -286,7 +286,7 @@ void QKeySequenceEdit::keyPressEvent(QKeyEvent *e)
     }
 
 
-    d->key[d->keyNum] = nextKey;
+    d->key[d->keyNum] = QKeyCombination::fromCombined(nextKey);
     d->keyNum++;
 
     QKeySequence key(d->key[0], d->key[1], d->key[2], d->key[3]);
diff --git a/src/widgets/widgets/qkeysequenceedit_p.h b/src/widgets/widgets/qkeysequenceedit_p.h
index 7af034e735..8cd58de68f 100644
--- a/src/widgets/widgets/qkeysequenceedit_p.h
+++ b/src/widgets/widgets/qkeysequenceedit_p.h
@@ -76,7 +76,7 @@ public:
     QLineEdit *lineEdit;
     QKeySequence keySequence;
     int keyNum;
-    int key[QKeySequencePrivate::MaxKeyCount];
+    QKeyCombination key[QKeySequencePrivate::MaxKeyCount];
     int prevKey;
     int releaseTimer;
 };
diff --git a/src/widgets/widgets/qmenu.cpp b/src/widgets/widgets/qmenu.cpp
index c2ef383d28..9007d2af78 100644
--- a/src/widgets/widgets/qmenu.cpp
+++ b/src/widgets/widgets/qmenu.cpp
@@ -3406,7 +3406,7 @@ void QMenu::keyPressEvent(QKeyEvent *e)
                         continue;
                     QAction *act = d->actions.at(i);
                     QKeySequence sequence = QKeySequence::mnemonic(act->text());
-                    int key = sequence[0] & 0xffff;
+                    int key = sequence[0].toCombined() & 0xffff; // suspicious
                     if (key == c.unicode()) {
                         clashCount++;
                         if (!first)
diff --git a/tests/auto/corelib/global/CMakeLists.txt b/tests/auto/corelib/global/CMakeLists.txt
index 29c696e121..4dab15eaab 100644
--- a/tests/auto/corelib/global/CMakeLists.txt
+++ b/tests/auto/corelib/global/CMakeLists.txt
@@ -11,6 +11,7 @@ add_subdirectory(qlogging)
 add_subdirectory(qtendian)
 add_subdirectory(qglobalstatic)
 add_subdirectory(qhooks)
+add_subdirectory(qkeycombination)
 if(WIN32)
     add_subdirectory(qwinregistry)
 endif()
diff --git a/tests/auto/corelib/global/global.pro b/tests/auto/corelib/global/global.pro
index 8af353728d..f3d1bbaaf5 100644
--- a/tests/auto/corelib/global/global.pro
+++ b/tests/auto/corelib/global/global.pro
@@ -6,6 +6,7 @@ SUBDIRS=\
     qglobal \
     qnumeric \
     qfloat16 \
+    qkeycombination \
     qrandomgenerator \
     qlogging \
     qtendian \
diff --git a/tests/auto/corelib/global/qkeycombination/.gitignore b/tests/auto/corelib/global/qkeycombination/.gitignore
new file mode 100644
index 0000000000..9ce23dd85c
--- /dev/null
+++ b/tests/auto/corelib/global/qkeycombination/.gitignore
@@ -0,0 +1 @@
+tst_qkeycombination
diff --git a/tests/auto/corelib/global/qkeycombination/CMakeLists.txt b/tests/auto/corelib/global/qkeycombination/CMakeLists.txt
new file mode 100644
index 0000000000..894e1e973f
--- /dev/null
+++ b/tests/auto/corelib/global/qkeycombination/CMakeLists.txt
@@ -0,0 +1,10 @@
+# Generated from qkeycombination.pro.
+
+#####################################################################
+## tst_qkeycombination Test:
+#####################################################################
+
+qt_add_test(tst_qkeycombination
+    SOURCES
+        tst_qkeycombination.cpp
+)
diff --git a/tests/auto/corelib/global/qkeycombination/qkeycombination.pro b/tests/auto/corelib/global/qkeycombination/qkeycombination.pro
new file mode 100644
index 0000000000..e2dd431055
--- /dev/null
+++ b/tests/auto/corelib/global/qkeycombination/qkeycombination.pro
@@ -0,0 +1,5 @@
+CONFIG += testcase
+TARGET = tst_qkeycombination
+QT = core testlib
+SOURCES = tst_qkeycombination.cpp
+
diff --git a/tests/auto/corelib/global/qkeycombination/tst_qkeycombination.cpp b/tests/auto/corelib/global/qkeycombination/tst_qkeycombination.cpp
new file mode 100644
index 0000000000..7e70cdb70f
--- /dev/null
+++ b/tests/auto/corelib/global/qkeycombination/tst_qkeycombination.cpp
@@ -0,0 +1,317 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QObject>
+#include <QTest>
+
+class tst_QKeyCombination : public QObject
+{
+    Q_OBJECT
+private slots:
+    void construction();
+    void operator_eq();
+    void operator_or();
+};
+
+constexpr int bitwiseOr()
+{
+    return 0;
+}
+
+template <typename ...T>
+constexpr auto bitwiseOr(T ... args)
+{
+    return (... | ((int)args));
+}
+
+void tst_QKeyCombination::construction()
+{
+    {
+        QKeyCombination combination;
+        QCOMPARE(combination.key(), Qt::Key_unknown);
+        QCOMPARE(combination.keyboardModifiers(), Qt::KeyboardModifiers{});
+        QCOMPARE(combination.toCombined(), bitwiseOr(Qt::Key_unknown));
+    }
+
+    {
+        QKeyCombination combination(Qt::CTRL); // explicit
+        QCOMPARE(combination.key(), Qt::Key_unknown);
+        QCOMPARE(combination.keyboardModifiers(), Qt::KeyboardModifiers(Qt::ControlModifier));
+        QCOMPARE(combination.toCombined(), bitwiseOr(Qt::ControlModifier, Qt::Key_unknown));
+    }
+
+    {
+        QKeyCombination combination(Qt::SHIFT); // explicit
+        QCOMPARE(combination.key(), Qt::Key_unknown);
+        QCOMPARE(combination.keyboardModifiers(), Qt::KeyboardModifiers(Qt::ShiftModifier));
+        QCOMPARE(combination.toCombined(), bitwiseOr(Qt::ShiftModifier, Qt::Key_unknown));
+    }
+
+    {
+        QKeyCombination combination(Qt::AltModifier); // explicit
+        QCOMPARE(combination.key(), Qt::Key_unknown);
+        QCOMPARE(combination.keyboardModifiers(), Qt::KeyboardModifiers(Qt::AltModifier));
+        QCOMPARE(combination.toCombined(), bitwiseOr(Qt::AltModifier, Qt::Key_unknown));
+    }
+
+    {
+        QKeyCombination combination(Qt::AltModifier | Qt::ControlModifier); // explicit
+        QCOMPARE(combination.key(), Qt::Key_unknown);
+        QCOMPARE(combination.keyboardModifiers(), Qt::KeyboardModifiers(Qt::AltModifier | Qt::ControlModifier));
+        QCOMPARE(combination.toCombined(), bitwiseOr(Qt::AltModifier, Qt::ControlModifier, Qt::Key_unknown));
+    }
+
+    {
+        QKeyCombination combination = Qt::Key_A; // implicit
+        QCOMPARE(combination.key(), Qt::Key_A);
+        QCOMPARE(combination.keyboardModifiers(), Qt::KeyboardModifiers{});
+        QCOMPARE(combination.toCombined(), bitwiseOr(Qt::Key_A));
+    }
+
+    {
+        QKeyCombination combination = Qt::Key_F1; // implicit
+        QCOMPARE(combination.key(), Qt::Key_F1);
+        QCOMPARE(combination.keyboardModifiers(), Qt::KeyboardModifiers{});
+        QCOMPARE(combination.toCombined(), bitwiseOr(Qt::Key_F1));
+    }
+
+    {
+        QKeyCombination combination(Qt::SHIFT, Qt::Key_F1);
+        QCOMPARE(combination.key(), Qt::Key_F1);
+        QCOMPARE(combination.keyboardModifiers(), Qt::KeyboardModifiers(Qt::ShiftModifier));
+        QCOMPARE(combination.toCombined(), bitwiseOr(Qt::SHIFT, Qt::Key_F1));
+    }
+
+    {
+        QKeyCombination combination(Qt::SHIFT | Qt::CTRL, Qt::Key_F1);
+        QCOMPARE(combination.key(), Qt::Key_F1);
+        QCOMPARE(combination.keyboardModifiers(), Qt::KeyboardModifiers(Qt::ShiftModifier | Qt::ControlModifier));
+        QCOMPARE(combination.toCombined(), bitwiseOr(Qt::SHIFT, Qt::CTRL, Qt::Key_F1));
+    }
+
+    {
+        QKeyCombination combination(Qt::AltModifier, Qt::Key_F1);
+        QCOMPARE(combination.key(), Qt::Key_F1);
+        QCOMPARE(combination.keyboardModifiers(), Qt::KeyboardModifiers(Qt::AltModifier));
+        QCOMPARE(combination.toCombined(), bitwiseOr(Qt::AltModifier, Qt::Key_F1));
+    }
+
+    // corner cases
+    {
+        QKeyCombination combination = Qt::Key_Alt;
+        QCOMPARE(combination.key(), Qt::Key_Alt);
+        QCOMPARE(combination.keyboardModifiers(), Qt::KeyboardModifiers{});
+        QCOMPARE(combination.toCombined(), bitwiseOr(Qt::Key_Alt));
+    }
+
+    {
+        QKeyCombination combination(Qt::ALT, Qt::Key_Alt);
+        QCOMPARE(combination.key(), Qt::Key_Alt);
+        QCOMPARE(combination.keyboardModifiers(), Qt::KeyboardModifiers(Qt::AltModifier));
+        QCOMPARE(combination.toCombined(), bitwiseOr(Qt::ALT, Qt::Key_Alt));
+    }
+
+    {
+        QKeyCombination combination(Qt::Key_unknown);
+        QCOMPARE(combination.key(), Qt::Key_unknown);
+        QCOMPARE(combination.keyboardModifiers(), Qt::KeyboardModifiers{});
+        QCOMPARE(combination.toCombined(), bitwiseOr(Qt::Key_unknown));
+    }
+
+    {
+        QKeyCombination combination(Qt::CTRL | Qt::SHIFT, Qt::Key_unknown);
+        QCOMPARE(combination.key(), Qt::Key_unknown);
+        QCOMPARE(combination.keyboardModifiers(), Qt::KeyboardModifiers(Qt::ControlModifier | Qt::ShiftModifier));
+        QCOMPARE(combination.toCombined(), bitwiseOr(Qt::CTRL, Qt::SHIFT, Qt::Key_unknown));
+    }
+}
+
+void tst_QKeyCombination::operator_eq()
+{
+    // default
+    {
+        QKeyCombination a, b;
+        QVERIFY(a == b);
+        QVERIFY(!(a != b));
+    }
+
+    // key only
+    {
+        QKeyCombination a;
+        QKeyCombination b(Qt::Key_X);
+        QVERIFY(a != b);
+        QVERIFY(!(a == b));
+    }
+
+    {
+        QKeyCombination a(Qt::Key_Y);
+        QKeyCombination b;
+        QVERIFY(a != b);
+        QVERIFY(!(a == b));
+    }
+
+    {
+        QKeyCombination a(Qt::Key_Y);
+        QKeyCombination b(Qt::Key_X);
+        QVERIFY(a != b);
+        QVERIFY(!(a == b));
+    }
+
+    {
+        QKeyCombination a(Qt::Key_F1);
+        QKeyCombination b(Qt::Key_F1);
+        QVERIFY(a == b);
+        QVERIFY(!(a != b));
+    }
+
+    // modifier only
+    {
+        QKeyCombination a;
+        QKeyCombination b(Qt::CTRL);
+        QVERIFY(a != b);
+        QVERIFY(!(a == b));
+    }
+
+    {
+        QKeyCombination a(Qt::CTRL);
+        QKeyCombination b;
+        QVERIFY(a != b);
+        QVERIFY(!(a == b));
+    }
+
+    {
+        QKeyCombination a(Qt::CTRL);
+        QKeyCombination b(Qt::SHIFT);
+        QVERIFY(a != b);
+        QVERIFY(!(a == b));
+    }
+
+    {
+        QKeyCombination a(Qt::CTRL);
+        QKeyCombination b(Qt::CTRL);
+        QVERIFY(a == b);
+        QVERIFY(!(a != b));
+    }
+
+    {
+        QKeyCombination a(Qt::CTRL);
+        QKeyCombination b(Qt::ControlModifier);
+        QVERIFY(a == b);
+        QVERIFY(!(a != b));
+    }
+
+    {
+        QKeyCombination a(Qt::ControlModifier);
+        QKeyCombination b(Qt::CTRL);
+        QVERIFY(a == b);
+        QVERIFY(!(a != b));
+    }
+
+    {
+        QKeyCombination a(Qt::ControlModifier);
+        QKeyCombination b(Qt::ControlModifier);
+        QVERIFY(a == b);
+        QVERIFY(!(a != b));
+    }
+
+    // key and modifier
+    {
+        QKeyCombination a(Qt::Key_A);
+        QKeyCombination b(Qt::SHIFT, Qt::Key_A);
+        QVERIFY(a != b);
+        QVERIFY(!(a == b));
+    }
+
+    {
+        QKeyCombination a(Qt::CTRL, Qt::Key_A);
+        QKeyCombination b(Qt::SHIFT, Qt::Key_A);
+        QVERIFY(a != b);
+        QVERIFY(!(a == b));
+    }
+
+    {
+        QKeyCombination a(Qt::SHIFT, Qt::Key_A);
+        QKeyCombination b(Qt::SHIFT, Qt::Key_A);
+        QVERIFY(a == b);
+        QVERIFY(!(a != b));
+    }
+
+    {
+        QKeyCombination a(Qt::SHIFT, Qt::Key_A);
+        QKeyCombination b(Qt::SHIFT, Qt::Key_Escape);
+        QVERIFY(a != b);
+        QVERIFY(!(a == b));
+    }
+
+    {
+        QKeyCombination a(Qt::SHIFT, Qt::Key_A);
+        QKeyCombination b(Qt::ShiftModifier, Qt::Key_A);
+        QVERIFY(a == b);
+        QVERIFY(!(a != b));
+    }
+
+    {
+        QKeyCombination a(Qt::SHIFT | Qt::CTRL, Qt::Key_A);
+        QKeyCombination b(Qt::ControlModifier | Qt::ShiftModifier, Qt::Key_A);
+        QVERIFY(a == b);
+        QVERIFY(!(a != b));
+    }
+
+    // corner cases
+    {
+        QKeyCombination a(Qt::CTRL);
+        QKeyCombination b(Qt::Key_Control);
+        QVERIFY(a != b);
+        QVERIFY(!(a == b));
+    }
+
+    {
+        QKeyCombination a(Qt::ALT);
+        QKeyCombination b(Qt::Key_Alt);
+        QVERIFY(a != b);
+        QVERIFY(!(a == b));
+    }
+}
+
+void tst_QKeyCombination::operator_or()
+{
+    // note tha operator+ between enumerators of the same enumeration
+    // yields int, so one can't do
+    //    Qt::SHIFT + Qt::CTRL + Qt::Key_A
+    // but one can do
+    //    Qt::SHIFT | Qt::CTRL | Qt::Key_A
+
+    QCOMPARE(Qt::SHIFT | Qt::Key_A, QKeyCombination(Qt::SHIFT, Qt::Key_A));
+    QCOMPARE(Qt::AltModifier | Qt::Key_F1, QKeyCombination(Qt::AltModifier, Qt::Key_F1));
+    QCOMPARE(Qt::SHIFT | Qt::ALT | Qt::Key_F1, QKeyCombination(Qt::SHIFT | Qt::ALT, Qt::Key_F1));
+    QCOMPARE(Qt::ControlModifier | Qt::Key_Escape, QKeyCombination(Qt::ControlModifier, Qt::Key_Escape));
+}
+
+QTEST_APPLESS_MAIN(tst_QKeyCombination)
+
+#include "tst_qkeycombination.moc"
diff --git a/tests/auto/gui/kernel/qkeysequence/tst_qkeysequence.cpp b/tests/auto/gui/kernel/qkeysequence/tst_qkeysequence.cpp
index c1272dc4cf..107c91507b 100644
--- a/tests/auto/gui/kernel/qkeysequence/tst_qkeysequence.cpp
+++ b/tests/auto/gui/kernel/qkeysequence/tst_qkeysequence.cpp
@@ -181,8 +181,9 @@ void tst_QKeySequence::swap()
     QKeySequence ks1(Qt::CTRL+Qt::Key_O);
     QKeySequence ks2(Qt::CTRL+Qt::Key_L);
     ks1.swap(ks2);
-    QCOMPARE(ks1[0], int(Qt::CTRL+Qt::Key_L));
-    QCOMPARE(ks2[0], int(Qt::CTRL+Qt::Key_O));
+
+    QCOMPARE(ks1[0], Qt::CTRL+Qt::Key_L);
+    QCOMPARE(ks2[0], Qt::CTRL+Qt::Key_O);
 }
 
 void tst_QKeySequence::operatorQString_data()