From 2cfabed1ff9c822458c467ff072e7a3a6c0fbf3d Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Fri, 1 Jul 2022 17:05:36 +0200
Subject: [PATCH] Long live QDebug op<< QMetaType!

It's needed in QtHttpServer.

[ChangeLog][QtCore][QDebug] Can now stream QMetaType.

[ChangeLog][QtCore][QMetaType] Can now be streamed through QDebug.

Change-Id: I974d77d678137715472a3907ab1e50ba2dbaa087
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/kernel/qmetatype.cpp            | 11 ++++++++++
 src/corelib/kernel/qmetatype.h              |  3 +++
 tests/auto/corelib/io/qdebug/tst_qdebug.cpp | 24 +++++++++++++++++++++
 3 files changed, 38 insertions(+)

diff --git a/src/corelib/kernel/qmetatype.cpp b/src/corelib/kernel/qmetatype.cpp
index 780ae10396..2760a67e8a 100644
--- a/src/corelib/kernel/qmetatype.cpp
+++ b/src/corelib/kernel/qmetatype.cpp
@@ -1703,6 +1703,17 @@ void QMetaType::unregisterConverterFunction(QMetaType from, QMetaType to)
 
 #ifndef QT_NO_DEBUG_STREAM
 
+/*!
+    \fn QDebug QMetaType::operator<<(QDebug d, QMetaType m)
+    \since 6.5
+    Writes the QMetaType \a m to the stream \a d, and returns the stream.
+*/
+QDebug operator<<(QDebug d, QMetaType m)
+{
+    const QDebugStateSaver saver(d);
+    return d.nospace() << "QMetaType(" << m.name() << ")";
+}
+
 /*!
     Streams the object at \a rhs to the debug stream \a dbg. Returns \c true
     on success, otherwise false.
diff --git a/src/corelib/kernel/qmetatype.h b/src/corelib/kernel/qmetatype.h
index 71153c3e8f..2e97e1892d 100644
--- a/src/corelib/kernel/qmetatype.h
+++ b/src/corelib/kernel/qmetatype.h
@@ -491,6 +491,9 @@ public:
     friend bool operator!=(QMetaType a, QMetaType b) { return !(a == b); }
 
 #ifndef QT_NO_DEBUG_STREAM
+private:
+    friend Q_CORE_EXPORT QDebug operator<<(QDebug d, QMetaType m);
+public:
     bool debugStream(QDebug& dbg, const void *rhs);
     bool hasRegisteredDebugStreamOperator() const;
 
diff --git a/tests/auto/corelib/io/qdebug/tst_qdebug.cpp b/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
index 400625ba7d..7be4c92002 100644
--- a/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
+++ b/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
@@ -14,8 +14,12 @@
 #include <QLine>
 #include <QMimeType>
 #include <QMimeDatabase>
+#include <QMetaType>
+
+using namespace Qt::StringLiterals;
 
 static_assert(QTypeTraits::has_ostream_operator_v<QDebug, int>);
+static_assert(QTypeTraits::has_ostream_operator_v<QDebug, QMetaType>);
 static_assert(QTypeTraits::has_ostream_operator_v<QDebug, QList<int>>);
 static_assert(QTypeTraits::has_ostream_operator_v<QDebug, QMap<int, QString>>);
 struct NonStreamable {};
@@ -54,6 +58,7 @@ private slots:
     void stateSaver() const;
     void veryLongWarningMessage() const;
     void qDebugQChar() const;
+    void qDebugQMetaType() const;
     void qDebugQString() const;
     void qDebugQStringView() const;
     void qDebugQUtf8StringView() const;
@@ -428,6 +433,25 @@ void tst_QDebug::qDebugQChar() const
 
 }
 
+void tst_QDebug::qDebugQMetaType() const
+{
+    QString file, function;
+    int line = 0;
+    MessageHandlerSetter mhs(myMessageHandler);
+    {
+        QDebug d = qDebug();
+        d << QMetaType::fromType<int>() << QMetaType::fromType<QString>();
+    }
+#ifndef QT_NO_MESSAGELOGCONTEXT
+    file = __FILE__; line = __LINE__ - 4; function = Q_FUNC_INFO;
+#endif
+    QCOMPARE(s_msgType, QtDebugMsg);
+    QCOMPARE(s_msg, R"(QMetaType(int) QMetaType(QString))"_L1);
+    QCOMPARE(QString::fromLatin1(s_file), file);
+    QCOMPARE(s_line, line);
+    QCOMPARE(QString::fromLatin1(s_function), function);
+}
+
 void tst_QDebug::qDebugQString() const
 {
     /* Use a basic string. */