QMetaType: Track whether type is QML list type

This information is required in the QML engine to handle list properties
(instances of QQmlListproperty<T> and list<T> types from QML).

Change-Id: I1e30572f1c91f58b290cb9b4b07433af99a1db6f
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
(cherry picked from commit 5806ecf5cb24cf39ea2608d42246eafbaa817582)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

2 files changed, 6 insertions, 0 deletions

diff --git a/src/corelib/kernel/qmetatype.cpp b/src/corelib/kernel/qmetatype.cpp
index d4ab51d323..ab3e47d4b1 100644
--- a/src/corelib/kernel/qmetatype.cpp
+++ b/src/corelib/kernel/qmetatype.cpp
@@ -420,6 +420,7 @@ Q_GLOBAL_STATIC(QMetaTypeCustomRegistry, customTypeRegistry)
     \omitvalue TrackingPointerToQObject
     \omitvalue IsGadget \omit This type is a Q_GADGET and it's corresponding QMetaObject can be accessed with QMetaType::metaObject Since 5.5. \endomit
     \omitvalue PointerToGadget
+    \omitvalue IsQmlListType
 */
 
 /*!
diff --git a/src/corelib/kernel/qmetatype.h b/src/corelib/kernel/qmetatype.h
index 8ef1bb8faa..e453c61d77 100644
--- a/src/corelib/kernel/qmetatype.h
+++ b/src/corelib/kernel/qmetatype.h
@@ -362,6 +362,7 @@ public:
         IsGadget = 0x200,
         PointerToGadget = 0x400,
         IsPointer = 0x800,
+        IsQmlList =0x1000, // used in the QML engine to recognize QQmlListProperty<T> and list<T>
     };
     Q_DECLARE_FLAGS(TypeFlags, TypeFlag)
 
@@ -1070,6 +1071,9 @@ namespace QtPrivate {
     template <typename Result, typename... Args>
     struct IsPointerToTypeDerivedFromQObject<Result(*)(Args...)> { enum { Value = false }; };
 
+    template<typename T>
+    inline constexpr bool IsQmlListType = false;
+
     template<typename T, bool = std::is_enum<T>::value>
     constexpr bool IsUnsignedEnum = false;
     template<typename T>
@@ -1090,6 +1094,7 @@ namespace QtPrivate {
                      | (IsPointerToGadgetHelper<T>::IsGadgetOrDerivedFrom ? QMetaType::PointerToGadget : 0)
                      | (QTypeInfo<T>::isPointer ? QMetaType::IsPointer : 0)
                      | (IsUnsignedEnum<T> ? QMetaType::IsUnsignedEnumeration : 0)
+                     | (IsQmlListType<T> ? QMetaType::IsQmlList : 0)
              };
     };