moc: Support signals that return movable-only type

By adding std::move where it makes sense.
This is not only good for move-only types, but for any type which
can be moved as it saves copies of the return value in any case.

[ChangeLog][moc] Move-only types are now supported as return types
of signals and slots.

Change-Id: Idc9453af993e7574a6bddd4a87210eddd3da48a9
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

1 files changed, 1 insertions, 6 deletions

diff --git a/src/corelib/kernel/qobjectdefs_impl.h b/src/corelib/kernel/qobjectdefs_impl.h
index bd08ca1763..3f5f2e78bb 100644
--- a/src/corelib/kernel/qobjectdefs_impl.h
+++ b/src/corelib/kernel/qobjectdefs_impl.h
@@ -90,14 +90,9 @@ namespace QtPrivate {
         explicit ApplyReturnValue(void *data_) : data(data_) {}
     };
     template<typename T, typename U>
-    void operator,(const T &value, const ApplyReturnValue<U> &container) {
-        if (container.data)
-            *reinterpret_cast<U*>(container.data) = value;
-    }
-    template<typename T, typename U>
     void operator,(T &&value, const ApplyReturnValue<U> &container) {
         if (container.data)
-            *reinterpret_cast<U*>(container.data) = value;
+            *reinterpret_cast<U *>(container.data) = std::forward<T>(value);
     }
     template<typename T>
     void operator,(T, const ApplyReturnValue<void> &) {}