Provide option to skip registration of enum classes unscoped

Enums classes are registered unscoped which leads to clashes in the following
cases:

1. Two different enums contain the same values
2. The name of an enum class is the same as an enum value

In the 2nd case you can not even access the scoped enum at all because it
will be overwritten by the primitive type.

Users can now add a class info to the meta type to disable the unscoped
registration which solves all clashes. The default is kept as is.

class MyClass : public QObject
{
    Q_OBJECT
    Q_CLASSINFO("RegisterEnumClassesUnscoped", "false")

public:
    ...
};

[ChangeLog][QtQml] Added option to disable unscoped registration of enum classes.

Change-Id: Ifa4197a14a252575e8a25ae56fb6ee479addf80b
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 41 insertions, 0 deletions

diff --git a/src/qml/doc/src/cppintegration/data.qdoc b/src/qml/doc/src/cppintegration/data.qdoc
index 7fb4724f73..6159ffe20b 100644
--- a/src/qml/doc/src/cppintegration/data.qdoc
+++ b/src/qml/doc/src/cppintegration/data.qdoc
@@ -420,6 +420,47 @@ To use an enum as a \l {QFlags}{flags} type in QML, see \l Q_FLAG().
 \note The names of enum values must begin with a capital letter in order to
 be accessible from QML.
 
+\code
+...
+enum class Status {
+          Ready,
+          Loading,
+          Error
+}
+Q_ENUM(Status)
+...
+\endcode
+
+Enum classes are registered in QML as scoped and unscoped properties.
+The \c Ready value will be registered at \c Message.Status.Ready and \c Message.Ready .
+
+When using enum classes, there can be multiple enums using the same identifiers.
+The unscoped registration will be overwriten by the last registered enum. For classes
+that contain such name conficts it is possible to disable the unscoped registration by
+annotating your class with a special Q_CLASSINFO macro.
+Use the name \c RegisterEnumClassesUnscoped with the value \c false to prevent scoped
+enums from being merged into the same name space.
+
+\code
+class Message : public QObject
+    {
+        Q_OBJECT
+        Q_CLASSINFO("RegisterEnumClassesUnscoped", "false")
+        Q_ENUM(ScopedEnum)
+        Q_ENUM(OtherValue)
+
+    public:
+        enum class ScopedEnum {
+              Value1,
+              Value2,
+              OtherValue
+        };
+        enum class OtherValue {
+              Value1,
+              Value2
+        };
+    };
+\endcode
 
 \section2 Enumeration Types as Signal and Method Parameters