1 files changed, 27 insertions, 10 deletions
diff --git a/src/corelib/kernel/qvariant.h b/src/corelib/kernel/qvariant.h
index a2c5711993..fe1ef1bdfc 100644
--- a/src/corelib/kernel/qvariant.h
+++ b/src/corelib/kernel/qvariant.h
@@ -53,6 +53,10 @@
 #include <QtCore/qbytearraylist.h>
 #endif
 
+#if QT_HAS_INCLUDE(<variant>) && __cplusplus >= 201703L
+#include <variant>
+#endif
+
 QT_BEGIN_NAMESPACE
 
 
@@ -284,14 +288,14 @@ class Q_CORE_EXPORT QVariant
     void detach();
     inline bool isDetached() const;
 
-    int toInt(bool *ok = Q_NULLPTR) const;
-    uint toUInt(bool *ok = Q_NULLPTR) const;
-    qlonglong toLongLong(bool *ok = Q_NULLPTR) const;
-    qulonglong toULongLong(bool *ok = Q_NULLPTR) const;
+    int toInt(bool *ok = nullptr) const;
+    uint toUInt(bool *ok = nullptr) const;
+    qlonglong toLongLong(bool *ok = nullptr) const;
+    qulonglong toULongLong(bool *ok = nullptr) const;
     bool toBool() const;
-    double toDouble(bool *ok = Q_NULLPTR) const;
-    float toFloat(bool *ok = Q_NULLPTR) const;
-    qreal toReal(bool *ok = Q_NULLPTR) const;
+    double toDouble(bool *ok = nullptr) const;
+    float toFloat(bool *ok = nullptr) const;
+    qreal toReal(bool *ok = nullptr) const;
     QByteArray toByteArray() const;
     QBitArray toBitArray() const;
     QString toString() const;
@@ -355,12 +359,21 @@ class Q_CORE_EXPORT QVariant
     static inline QVariant fromValue(const T &value)
     { return qVariantFromValue(value); }
 
+#if QT_HAS_INCLUDE(<variant>) && __cplusplus >= 201703L
+    template<typename... Types>
+    static inline QVariant fromStdVariant(const std::variant<Types...> &value)
+    {
+        if (value.valueless_by_exception())
+            return QVariant();
+        return std::visit([](const auto &arg) { return fromValue(arg); }, value);
+    }
+#endif
+
     template<typename T>
     bool canConvert() const
     { return canConvert(qMetaTypeId<T>()); }
 
  public:
-#ifndef Q_QDOC
     struct PrivateShared
     {
         inline PrivateShared(void *v) : ptr(v), ref(1) { }
@@ -370,7 +383,7 @@ class Q_CORE_EXPORT QVariant
     struct Private
     {
         inline Private() Q_DECL_NOTHROW : type(Invalid), is_shared(false), is_null(true)
-        { data.ptr = Q_NULLPTR; }
+        { data.ptr = nullptr; }
 
         // Internal constructor for initialized variants.
         explicit inline Private(uint variantType) Q_DECL_NOTHROW
@@ -431,7 +444,6 @@ class Q_CORE_EXPORT QVariant
         f_canConvert canConvert;
         f_debugStream debugStream;
     };
-#endif
 
     inline bool operator==(const QVariant &v) const
     { return cmp(v); }
@@ -505,6 +517,11 @@ inline QVariant qVariantFromValue(const T &t)
 template <>
 inline QVariant qVariantFromValue(const QVariant &t) { return t; }
 
+#if QT_HAS_INCLUDE(<variant>) && __cplusplus >= 201703L
+template <>
+inline QVariant qVariantFromValue(const std::monostate &) { return QVariant(); }
+#endif
+
 template <typename T>
 inline void qVariantSetValue(QVariant &v, const T &t)
 {