Add support for converting from std::variant

Adds inline handling of the C++17 type std::variant, so the type will
be resolved if converted into a QVariant.

Change-Id: I31809d70d7f347277389d42a3695836ec7a32d02
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 41 insertions, 1 deletions

diff --git a/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp b/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp
index 5d19cb8428..9eb8071ff3 100644
--- a/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp
+++ b/tests/auto/corelib/kernel/qvariant/tst_qvariant.cpp
@@ -45,7 +45,9 @@
 #include <limits.h>
 #include <float.h>
 #include <cmath>
-
+#if QT_HAS_INCLUDE(<variant>) && __cplusplus >= 201703L
+#include <variant>
+#endif
 #include <QLinkedList>
 #include <QRegularExpression>
 #include <QDir>
@@ -281,6 +283,8 @@ private slots:
 
     void accessSequentialContainerKey();
 
+    void fromStdVariant();
+
 private:
     void dataStream_data(QDataStream::Version version);
     void loadQVariantFromDataStream(QDataStream::Version version);
@@ -4944,5 +4948,41 @@ void tst_QVariant::accessSequentialContainerKey()
     QCOMPARE(nameResult, QStringLiteral("Seven"));
 }
 
+void tst_QVariant::fromStdVariant()
+{
+#if QT_HAS_INCLUDE(<variant>) && __cplusplus >= 201703L
+    {
+        typedef std::variant<int, bool> intorbool_t;
+        intorbool_t stdvar = 5;
+        QVariant qvar = QVariant::fromStdVariant(stdvar);
+        QVERIFY(!qvar.isNull());
+        QCOMPARE(qvar.type(), QVariant::Int);
+        QCOMPARE(qvar.value<int>(), std::get<int>(stdvar));
+        stdvar = true;
+        qvar = QVariant::fromStdVariant(stdvar);
+        QVERIFY(!qvar.isNull());
+        QCOMPARE(qvar.type(), QVariant::Bool);
+        QCOMPARE(qvar.value<bool>(), std::get<bool>(stdvar));
+    }
+    {
+        std::variant<std::monostate, int> stdvar;
+        QVariant qvar = QVariant::fromStdVariant(stdvar);
+        QVERIFY(!qvar.isValid());
+        stdvar = -4;
+        qvar = QVariant::fromStdVariant(stdvar);
+        QVERIFY(!qvar.isNull());
+        QCOMPARE(qvar.type(), QVariant::Int);
+        QCOMPARE(qvar.value<int>(), std::get<int>(stdvar));
+    }
+    {
+        std::variant<int, bool, QChar> stdvar = QChar::fromLatin1(' ');
+        QVariant qvar = QVariant::fromStdVariant(stdvar);
+        QVERIFY(!qvar.isNull());
+        QCOMPARE(qvar.type(), QVariant::Char);
+        QCOMPARE(qvar.value<QChar>(), std::get<QChar>(stdvar));
+    }
+#endif
+}
+
 QTEST_MAIN(tst_QVariant)
 #include "tst_qvariant.moc"