QSP/QWP: introduce owner_before, owner_equal, owner_hash

While at the moment we don't have aliasing support in QSharedPointer,
introduce owner-based comparisons and hashing. This also fulfills some
use cases in lieu of operator== for QWeakPointer (which got deprecated
by bb23a05905d7dc0e416a646e40592436daa939f2).

I'm using C++26/P1901's spelling of owner_equal, instead of
Boost.SmartPtr's spelling (owner_equal*s*). Given the niche use case,
the lack of interoperability with Qt's own containers, as well as the
Standard comparison objects' semantics (std::owner_less,
std::owner_equal), I don't think we should be giving these a Qt-ish name
as it would be pretty useless.

[ChangeLog][QtCore][QSharedPointer] Added owner_before, owner_equal,
owner_hash.
[ChangeLog][QtCore][QWeakPointer] Added owner_before, owner_equal,
owner_hash.

Done-with: Fabian Kosmale <fabian.kosmale@qt.io>
Change-Id: I8b792ae79f14cd518ba4a006edaa17786a8352a0
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 136 insertions, 0 deletions

diff --git a/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp b/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
index 5c4514eeb4..93cab2f4d9 100644
--- a/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
+++ b/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
@@ -91,6 +91,7 @@ private slots:
     void invalidConstructs_data();
     void invalidConstructs();
 #endif
+    void ownerComparisons();
 
     // let invalidConstructs be the last test, because it's the slowest;
     // add new tests above this block
@@ -2841,5 +2842,140 @@ void tst_QSharedPointer::overloads()
     weakOverloaded.test();
 }
 
+void tst_QSharedPointer::ownerComparisons()
+{
+    using SP = QSharedPointer<int>;
+    using WP = QWeakPointer<int>;
+
+#define CHECK_EQ(a, b) \
+    do { \
+        QVERIFY(a.owner_equal(b)); \
+        QVERIFY(b.owner_equal(a)); \
+        QVERIFY(!a.owner_before(b)); \
+        QVERIFY(!b.owner_before(a)); \
+        QVERIFY(a.owner_hash() == b.owner_hash()); \
+    } while (false)
+
+#define CHECK_NOT_EQ(a, b) \
+    do { \
+        QVERIFY(!a.owner_equal(b)); \
+        QVERIFY(!b.owner_equal(a)); \
+        QVERIFY(a.owner_before(b) || b.owner_before(a)); \
+    } while (false)
+
+    // null
+    {
+        SP sp1;
+        SP sp2;
+        WP wp1 = sp1;
+        WP wp2;
+
+        CHECK_EQ(sp1, sp1);
+        CHECK_EQ(sp1, sp2);
+        CHECK_EQ(sp1, wp1);
+        CHECK_EQ(sp2, wp2);
+        CHECK_EQ(wp1, wp1);
+        CHECK_EQ(wp1, wp2);
+        CHECK_EQ(wp2, wp2);
+    }
+
+    // same owner
+    {
+        SP sp1 = SP::create(123);
+        SP sp2 = sp1;
+        WP wp1 = sp1;
+        SP wp2 = sp2;
+
+        CHECK_EQ(sp1, sp1);
+        CHECK_EQ(sp1, sp2);
+        CHECK_EQ(sp1, wp1);
+        CHECK_EQ(sp2, wp2);
+        CHECK_EQ(wp1, wp1);
+        CHECK_EQ(wp1, wp2);
+    }
+
+    // owning vs null
+    {
+        SP sp1 = SP::create(123);
+        SP sp2;
+        WP wp1 = sp1;
+        WP wp2 = sp2;
+
+        CHECK_EQ(sp1, sp1);
+        CHECK_NOT_EQ(sp1, sp2);
+        CHECK_EQ(sp1, wp1);
+        CHECK_EQ(sp2, wp2);
+        CHECK_EQ(wp1, wp1);
+        CHECK_NOT_EQ(wp1, wp2);
+    }
+
+    // different owners
+    {
+        SP sp1 = SP::create(123);
+        SP sp2 = SP::create(456);
+        WP wp1 = sp1;
+        WP wp2 = sp2;
+
+        CHECK_EQ(sp1, sp1);
+        CHECK_NOT_EQ(sp1, sp2);
+        CHECK_EQ(sp1, wp1);
+        CHECK_EQ(sp2, wp2);
+        CHECK_EQ(wp1, wp1);
+        CHECK_NOT_EQ(wp1, wp2);
+    }
+
+    // reset vs. null
+    {
+        SP sp1 = SP::create(123);
+        SP sp2;
+        WP wp1 = sp1;
+        WP wp2;
+
+        CHECK_EQ(sp1, sp1);
+        CHECK_NOT_EQ(sp1, sp2);
+        CHECK_EQ(sp1, wp1);
+        CHECK_NOT_EQ(sp1, wp2);
+        CHECK_EQ(wp1, wp1);
+        CHECK_NOT_EQ(wp1, wp2);
+
+        sp1.reset();
+
+        CHECK_EQ(sp1, sp1);
+        CHECK_EQ(sp1, sp2);
+        CHECK_NOT_EQ(sp1, wp1);
+        CHECK_EQ(sp2, wp2);
+        CHECK_EQ(wp1, wp1);
+        CHECK_NOT_EQ(wp1, wp2);
+    }
+
+    // expired weak pointers
+    {
+        WP wp1 = SP::create(123);
+        WP wp2;
+
+        CHECK_EQ(wp1, wp1);
+        CHECK_NOT_EQ(wp1, wp2);
+    }
+
+    {
+        WP wp1 = SP::create(123);
+        WP wp2 = wp1;
+
+        CHECK_EQ(wp1, wp1);
+        CHECK_EQ(wp1, wp2);
+    }
+
+    {
+        WP wp1 = SP::create(123);
+        WP wp2 = SP::create(456);
+
+        CHECK_EQ(wp1, wp1);
+        CHECK_EQ(wp2, wp2);
+        CHECK_NOT_EQ(wp1, wp2);
+    }
+#undef CHECK_EQ
+#undef CHECK_NOT_EQ
+}
+
 QTEST_MAIN(tst_QSharedPointer)
 #include "tst_qsharedpointer.moc"