tst_QGlobal: add a check for Q_DECLARE_SHARED

Check that it marks types are Q_RELOCATABLE_TYPE and adds the ADL
swap().

Pick-to: 6.7 6.5
Change-Id: Ibde0f4ad594e4a6b3636357da2fd211507293b60
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
(cherry picked from commit 91a96ea8fb100fca08b37eb3ba644083b3316e6d)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

tests/auto/corelib/global/qglobal/tst_qglobal.cpp

@@ -14,7 +14,37 @@
 
 #include <cmath>
 #include <limits>
-#include <type_traits>
+#include <QtCore/qxptype_traits.h>
+
+template <typename T>
+using AdlSwappableTest = decltype(swap(std::declval<T&>(), std::declval<T&>()));
+
+template <typename T>
+constexpr bool q_is_adl_swappable_v = qxp::is_detected_v<AdlSwappableTest, T>;
+
+QT_BEGIN_NAMESPACE
+
+//
+// Check Q_DECLARE_SHARED
+//
+#define MAKE_CLASS(C) \
+    struct C \
+    { \
+        std::string s; \
+        explicit C(std::string s = {}) : s{std::move(s)} {} \
+        void swap(C &other) noexcept { std::swap(s, other.s); } \
+    } \
+    /* end */
+
+MAKE_CLASS(NotQDeclareShared);
+static_assert(!q_is_adl_swappable_v<NotQDeclareShared>);
+
+MAKE_CLASS(Terry); // R.I.P.
+Q_DECLARE_SHARED(Terry)
+
+#undef MAKE_CLASS
+
+QT_END_NAMESPACE
 
 class tst_QGlobal: public QObject
 {
@@ -31,6 +61,8 @@ private slots:
     void qConstructorFunction();
     void qCoreAppStartupFunction();
     void qCoreAppStartupFunctionRestart();
+    void qDeclareSharedMarksTheTypeRelocatable();
+    void qDeclareSharedMakesTheTypeAdlSwappable();
     void integerForSize();
     void int128Literals();
     void buildAbiEndianness();
@@ -395,6 +427,32 @@ void tst_QGlobal::qCoreAppStartupFunctionRestart()
     qCoreAppStartupFunction();
 }
 
+void tst_QGlobal::qDeclareSharedMarksTheTypeRelocatable()
+{
+    static_assert(!QTypeInfo<QT_PREPEND_NAMESPACE(NotQDeclareShared)>::isRelocatable);
+    static_assert( QTypeInfo<QT_PREPEND_NAMESPACE(Terry)>::isRelocatable);
+}
+
+void tst_QGlobal::qDeclareSharedMakesTheTypeAdlSwappable()
+{
+    static_assert(!q_is_adl_swappable_v<QT_PREPEND_NAMESPACE(NotQDeclareShared)>);
+    static_assert( q_is_adl_swappable_v<QT_PREPEND_NAMESPACE(Terry)>);
+
+    #define CHECK(Class) do { \
+        using C = QT_PREPEND_NAMESPACE(Class); \
+        C lhs("lhs"); \
+        C rhs("rhs"); \
+        QCOMPARE_EQ(lhs.s, "lhs"); \
+        QCOMPARE_EQ(rhs.s, "rhs"); \
+        /* no using std::swap - we're checking whether the ADL swap works */ \
+        swap(lhs, rhs); \
+        QCOMPARE_EQ(lhs.s, "rhs"); \
+        QCOMPARE_EQ(rhs.s, "lhs"); \
+    } while (false)
+    CHECK(Terry);
+    #undef CHECK
+}
+
 struct isEnum_A {
     int n_;
 };