QT_SPECIALIZE_STD_HASH_TO_CALL_QHASH: use unqualified qHash() lookup

... instead of QT_PREPEND_NAMESPACE(qHash), which is qualified (prepends at least '::'), and therefore disables ADL.

This is not a problem as long as we wrote our qHash() overloads as free functions (incl. non-hidden friends), but it should™ fail for hidden friends, so use the old using-std::swap() trick to bring QT_PREPEND_NAMESPACE(qHash) into scope, proceeding with an unqualified lookup.

Pick-to: 6.2
Change-Id: I00860b2313699849f86bfe3dd9f41db4ce993cd3
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 26 insertions, 0 deletions

diff --git a/tests/auto/corelib/tools/qhashfunctions/tst_qhashfunctions.cpp b/tests/auto/corelib/tools/qhashfunctions/tst_qhashfunctions.cpp
index 86305b101f..3281c4cefd 100644
--- a/tests/auto/corelib/tools/qhashfunctions/tst_qhashfunctions.cpp
+++ b/tests/auto/corelib/tools/qhashfunctions/tst_qhashfunctions.cpp
@@ -303,9 +303,35 @@ void tst_QHashFunctions::rangeCommutative()
     }
 }
 
+// QVarLengthArray these days has a qHash() as a hidden friend.
+// This checks that QT_SPECIALIZE_STD_HASH_TO_CALL_QHASH can deal with that:
+
+QT_BEGIN_NAMESPACE
+QT_SPECIALIZE_STD_HASH_TO_CALL_QHASH_BY_CREF(QVarLengthArray<QVector<int>>)
+QT_END_NAMESPACE
+
 void tst_QHashFunctions::stdHash()
 {
     {
+        std::unordered_set<QVarLengthArray<QVector<int>>> s = {
+            {
+                {0, 1, 2},
+                {42, 43, 44},
+                {},
+            }, {
+                {11, 12, 13},
+                {},
+            },
+        };
+        QCOMPARE(s.size(), 2UL);
+        s.insert({
+                     {11, 12, 13},
+                     {},
+                 });
+        QCOMPARE(s.size(), 2UL);
+    }
+
+    {
         std::unordered_set<QString> s = {QStringLiteral("Hello"), QStringLiteral("World")};
         QCOMPARE(s.size(), 2UL);
         s.insert(QStringLiteral("Hello"));