Fix build error with Qt >= 6.5 (fixes #128)

thp · Dec 2, 2023 · 4504425 · 4504425
1 parent 63eb529
commit 4504425
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diff --git a/docs/index.rst b/docs/index.rst
@@ -1196,9 +1196,14 @@ flags for compiling and linking against Python on your system.
 ChangeLog
 =========
 
-Version 1.6.0 (2022-08-05)
+Version UNRELEASED (YYYY-MM-DD)
 -------------------------------
 
+* Support for Qt 6.5 and newer (backwards-incompatible ``Q_RETURN_ARG()`` change) (fixes #128)
+
+Version 1.6.0 (2022-08-05)
+--------------------------
+
 * Support for **Qt 6** (Qt 5 is still supported for now)
 * Use ``PyUnicode_AsUTF8`` from Python 3.3 when converting strings; strings returned
   from the converter are now valid as long as the ``PyObject`` is alive (previously

diff --git a/src/qpython_priv.cpp b/src/qpython_priv.cpp
@@ -405,8 +405,25 @@ pyotherside_QObjectMethod_call(PyObject *callable_object, PyObject *args, PyObje
             }
 
             QVariant result;
+#if QT_VERSION < QT_VERSION_CHECK(6, 5, 0)
+            QGenericReturnArgument returnArg = Q_RETURN_ARG(QVariant, result);
+#else
+            /**
+             * Starting with Qt 6.5, Q_RETURN_ARG() expands to a QMetaMethodReturnArgument,
+             * whereas previously it returned a QGenericReturnArgument. Since we are using
+             * the old, deprecated QMetaMethod::invoke() functions, and those take a
+             * QGenericReturnArgument and not a QMetaMethodReturnArgument, we need to
+             * create the QGenericReturnArgument ourselves by emulating what Q_RETURN_ARG()
+             * does in old Qt versions before 6.5.
+             *
+             * See also:
+             * https://bugreports.qt.io/browse/QTBUG-113147
+             * https://github.com/thp/pyotherside/issues/128
+             **/
+            QGenericReturnArgument returnArg {QT_STRINGIFY(QVariant), &result};
+#endif
             if (method.invoke(o, Qt::DirectConnection,
-                    Q_RETURN_ARG(QVariant, result), genericArguments.value(0),
+                    returnArg, genericArguments.value(0),
                     genericArguments.value(1), genericArguments.value(2),
                     genericArguments.value(3), genericArguments.value(4),
                     genericArguments.value(5), genericArguments.value(6),