diff options
author | Fabian Kosmale <fabian.kosmale@qt.io> | 2020-10-26 14:30:08 +0100 |
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committer | Fabian Kosmale <fabian.kosmale@qt.io> | 2020-10-27 16:43:12 +0100 |
commit | 331a200b9746177d84deb06675be5f31bd1ae079 (patch) | |
tree | 3bac94216d2086e029b1b16eecc027b2b810815d /src/corelib/kernel/qobject_impl.h | |
parent | c293ab71bd45b36870aa016663b6f340aa1d4a8e (diff) |
Revert "QObject: simplify part of connection logic"
This reverts commit 1918c689d78b0f6a718343e7ebceb387acc32a97.
The template gets always instantiated in QObjectPrivate::connect, even
if the connection types is not Qt::(Blocking)QueuedConnection. For
non-queued connections we however support using incomplete types in
connect. The only way to fix this would be to make the connection type a
template parameter of QObjectPrivate::connect (or at lesat pass some
compile time constant indicating "blocking"-ness) along, so that we can
use if constexpr instead of if. As all involved classes are private, we
can postpone investigating this solution to 6.1
Change-Id: Ieffaf015f8e60ca6ac6f85eb9e2756e480060b4f
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Diffstat (limited to 'src/corelib/kernel/qobject_impl.h')
-rw-r--r-- | src/corelib/kernel/qobject_impl.h | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/src/corelib/kernel/qobject_impl.h b/src/corelib/kernel/qobject_impl.h index 722ebec847..0c36417a24 100644 --- a/src/corelib/kernel/qobject_impl.h +++ b/src/corelib/kernel/qobject_impl.h @@ -56,10 +56,23 @@ namespace QtPrivate { Logic to statically generate the array of qMetaTypeId ConnectionTypes<FunctionPointer<Signal>::Arguments>::types() returns an array of int that is suitable for the types arguments of the connection functions. + + The array only exist of all the types are declared as a metatype + (detected using the TypesAreDeclaredMetaType helper struct) + If one of the type is not declared, the function return 0 and the signal + cannot be used in queued connection. */ - template <typename T> struct ConnectionTypes; - template <typename... Args> struct ConnectionTypes<List<Args...>> - { static const int *types() { static const int t[sizeof...(Args) + 1] = { QMetaType::fromType<Args>().id()..., 0 }; return t; } }; + template <typename ArgList> struct TypesAreDeclaredMetaType { enum { Value = false }; }; + template <> struct TypesAreDeclaredMetaType<List<>> { enum { Value = true }; }; + template <typename Arg, typename... Tail> struct TypesAreDeclaredMetaType<List<Arg, Tail...> > + { enum { Value = QMetaTypeId2<Arg>::Defined && TypesAreDeclaredMetaType<List<Tail...>>::Value }; }; + + template <typename ArgList, bool Declared = TypesAreDeclaredMetaType<ArgList>::Value > struct ConnectionTypes + { static const int *types() { return nullptr; } }; + template <> struct ConnectionTypes<List<>, true> + { static const int *types() { return nullptr; } }; + template <typename... Args> struct ConnectionTypes<List<Args...>, true> + { static const int *types() { static const int t[sizeof...(Args) + 1] = { (QtPrivate::QMetaTypeIdHelper<Args>::qt_metatype_id())..., 0 }; return t; } }; // implementation of QSlotObjectBase for which the slot is a static function // Args and R are the List of arguments and the return type of the signal to which the slot is connected. |