Add a runtime warning when dummy QtBluetooth backend is running

There have been plenty of bugs where QtBluetooth was compiled
with the dummy backend and the API user reported bugs against it. So far
debug output was not able to identify the dummy backend which made
debugging of customer code more difficult.

This patch prints the name of the backend once shortly after the
application startup. The other backends like Bluez do that already.

Change-Id: I86353ef3c9c99cafac38805f253e20a3ad3e10a5
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@theqtcompany.com>

12 files changed, 134 insertions, 1 deletions

diff --git a/src/bluetooth/bluetooth.pro b/src/bluetooth/bluetooth.pro
index 359ecf4a..89839be1 100644
--- a/src/bluetooth/bluetooth.pro
+++ b/src/bluetooth/bluetooth.pro
@@ -182,7 +182,8 @@ config_bluez:qtHaveModule(dbus) {
     SOURCES -= qlowenergycontroller.cpp
 } else {
     message("Unsupported Bluetooth platform, will not build a working QtBluetooth library.")
-    message("Either no Qt D-Bus found or no BlueZ headers.")
+    message("Either no Qt D-Bus found or no BlueZ headers available.")
+    include(dummy/dummy.pri)
     SOURCES += \
         qbluetoothdevicediscoveryagent_p.cpp \
         qbluetoothlocaldevice_p.cpp \
diff --git a/src/bluetooth/dummy/dummy.pri b/src/bluetooth/dummy/dummy.pri
new file mode 100644
index 00000000..49aa076c
--- /dev/null
+++ b/src/bluetooth/dummy/dummy.pri
@@ -0,0 +1,2 @@
+HEADERS += dummy/dummy_helper_p.h
+SOURCES += dummy/dummy_helper.cpp
diff --git a/src/bluetooth/dummy/dummy_helper.cpp b/src/bluetooth/dummy/dummy_helper.cpp
new file mode 100644
index 00000000..fc78ea2f
--- /dev/null
+++ b/src/bluetooth/dummy/dummy_helper.cpp
@@ -0,0 +1,53 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the QtBluetooth module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtCore/QGlobalStatic>
+#include <QtCore/QLoggingCategory>
+
+#include "dummy_helper_p.h"
+
+QT_BEGIN_NAMESPACE
+
+Q_DECLARE_LOGGING_CATEGORY(QT_BT)
+
+Q_GLOBAL_STATIC_WITH_ARGS(bool, dummyWarningPrinted, (false))
+
+void printDummyWarning()
+{
+    if (!*dummyWarningPrinted()) {
+        qCWarning(QT_BT) << "Dummy backend running. Qt Bluetooth module is non-functional.";
+        *dummyWarningPrinted() = true;
+    }
+}
+
+QT_END_NAMESPACE
diff --git a/src/bluetooth/dummy/dummy_helper_p.h b/src/bluetooth/dummy/dummy_helper_p.h
new file mode 100644
index 00000000..f548ac36
--- /dev/null
+++ b/src/bluetooth/dummy/dummy_helper_p.h
@@ -0,0 +1,56 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the QtBluetooth module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef DUMMY_HELPER_H
+#define DUMMY_HELPER_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include "QtCore/qglobal.h"
+
+QT_BEGIN_NAMESPACE
+
+void printDummyWarning();
+
+QT_END_NAMESPACE
+
+#endif // DUMMY_HELPER_H
diff --git a/src/bluetooth/qbluetoothdevicediscoveryagent_p.cpp b/src/bluetooth/qbluetoothdevicediscoveryagent_p.cpp
index 26052a52..963eb368 100644
--- a/src/bluetooth/qbluetoothdevicediscoveryagent_p.cpp
+++ b/src/bluetooth/qbluetoothdevicediscoveryagent_p.cpp
@@ -36,6 +36,8 @@
 #include "qbluetoothaddress.h"
 #include "qbluetoothuuid.h"
 
+#include "dummy/dummy_helper_p.h"
+
 #define QT_DEVICEDISCOVERY_DEBUG
 
 QT_BEGIN_NAMESPACE
@@ -48,6 +50,7 @@ QBluetoothDeviceDiscoveryAgentPrivate::QBluetoothDeviceDiscoveryAgentPrivate(
         q_ptr(parent)
 {
     Q_UNUSED(deviceAdapter);
+    printDummyWarning();
 }
 
 QBluetoothDeviceDiscoveryAgentPrivate::~QBluetoothDeviceDiscoveryAgentPrivate()
diff --git a/src/bluetooth/qbluetoothlocaldevice_p.cpp b/src/bluetooth/qbluetoothlocaldevice_p.cpp
index 0b7c5c44..20c02558 100644
--- a/src/bluetooth/qbluetoothlocaldevice_p.cpp
+++ b/src/bluetooth/qbluetoothlocaldevice_p.cpp
@@ -35,6 +35,7 @@
 #include "qbluetoothaddress.h"
 
 #include "qbluetoothlocaldevice_p.h"
+#include "dummy/dummy_helper_p.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -42,6 +43,7 @@ QBluetoothLocalDevice::QBluetoothLocalDevice(QObject *parent) :
     QObject(parent),
     d_ptr(0)
 {
+    printDummyWarning();
     registerQBluetoothLocalDeviceMetaType();
 }
 
diff --git a/src/bluetooth/qbluetoothserver_p.cpp b/src/bluetooth/qbluetoothserver_p.cpp
index 86b520d6..4f9ce433 100644
--- a/src/bluetooth/qbluetoothserver_p.cpp
+++ b/src/bluetooth/qbluetoothserver_p.cpp
@@ -34,12 +34,14 @@
 #include "qbluetoothserver.h"
 #include "qbluetoothserver_p.h"
 #include "qbluetoothsocket.h"
+#include "dummy/dummy_helper_p.h"
 
 QT_BEGIN_NAMESPACE
 
 QBluetoothServerPrivate::QBluetoothServerPrivate(QBluetoothServiceInfo::Protocol sType)
     : maxPendingConnections(1), serverType(sType), m_lastError(QBluetoothServer::NoError)
 {
+    printDummyWarning();
     if (sType == QBluetoothServiceInfo::RfcommProtocol)
         socket = new QBluetoothSocket(QBluetoothServiceInfo::RfcommProtocol);
     else
diff --git a/src/bluetooth/qbluetoothservicediscoveryagent_p.cpp b/src/bluetooth/qbluetoothservicediscoveryagent_p.cpp
index 738fe739..263e9018 100644
--- a/src/bluetooth/qbluetoothservicediscoveryagent_p.cpp
+++ b/src/bluetooth/qbluetoothservicediscoveryagent_p.cpp
@@ -33,6 +33,7 @@
 
 #include "qbluetoothservicediscoveryagent.h"
 #include "qbluetoothservicediscoveryagent_p.h"
+#include "dummy/dummy_helper_p.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -41,6 +42,7 @@ QBluetoothServiceDiscoveryAgentPrivate::QBluetoothServiceDiscoveryAgentPrivate(c
        deviceDiscoveryAgent(0), mode(QBluetoothServiceDiscoveryAgent::MinimalDiscovery),
        singleDevice(false)
 {
+    printDummyWarning();
     Q_UNUSED(deviceAdapter);
 }
 
diff --git a/src/bluetooth/qbluetoothserviceinfo_p.cpp b/src/bluetooth/qbluetoothserviceinfo_p.cpp
index 8942149a..dbf3abfc 100644
--- a/src/bluetooth/qbluetoothserviceinfo_p.cpp
+++ b/src/bluetooth/qbluetoothserviceinfo_p.cpp
@@ -33,11 +33,13 @@
 
 #include "qbluetoothserviceinfo.h"
 #include "qbluetoothserviceinfo_p.h"
+#include "dummy/dummy_helper_p.h"
 
 QT_BEGIN_NAMESPACE
 
 QBluetoothServiceInfoPrivate::QBluetoothServiceInfoPrivate()
 {
+    printDummyWarning();
 }
 
 QBluetoothServiceInfoPrivate::~QBluetoothServiceInfoPrivate()
diff --git a/src/bluetooth/qbluetoothsocket_p.cpp b/src/bluetooth/qbluetoothsocket_p.cpp
index 13b32045..6b196a81 100644
--- a/src/bluetooth/qbluetoothsocket_p.cpp
+++ b/src/bluetooth/qbluetoothsocket_p.cpp
@@ -33,6 +33,7 @@
 
 #include "qbluetoothsocket.h"
 #include "qbluetoothsocket_p.h"
+#include "dummy/dummy_helper_p.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -43,6 +44,7 @@ QBluetoothSocketPrivate::QBluetoothSocketPrivate()
       socketError(QBluetoothSocket::NoSocketError),
       secFlags(QBluetooth::NoSecurity)
 {
+    printDummyWarning();
 }
 
 QBluetoothSocketPrivate::~QBluetoothSocketPrivate()
diff --git a/src/bluetooth/qbluetoothtransfermanager.cpp b/src/bluetooth/qbluetoothtransfermanager.cpp
index de7693d7..52cefdf8 100644
--- a/src/bluetooth/qbluetoothtransfermanager.cpp
+++ b/src/bluetooth/qbluetoothtransfermanager.cpp
@@ -38,6 +38,8 @@
 #include "qbluetoothtransferreply_bluez_p.h"
 #elif QT_OSX_BLUETOOTH
 #include "qbluetoothtransferreply_osx_p.h"
+#else
+#include "dummy/dummy_helper_p.h"
 #endif
 
 QT_BEGIN_NAMESPACE
@@ -111,6 +113,10 @@ QBluetoothTransferReply *QBluetoothTransferManager::put(const QBluetoothTransfer
     connect(reply, SIGNAL(finished(QBluetoothTransferReply*)), this, SIGNAL(finished(QBluetoothTransferReply*)));
     return reply;
 #else
+    // Android and iOS have no implementation
+#if !defined(QT_ANDROID_BLUETOOTH) && !defined(QT_IOS_BLUETOOTH)
+    printDummyWarning();
+#endif
     Q_UNUSED(request);
     Q_UNUSED(data);
     return 0;
diff --git a/src/bluetooth/qlowenergycontroller_p.cpp b/src/bluetooth/qlowenergycontroller_p.cpp
index c16e2733..9cbc6633 100644
--- a/src/bluetooth/qlowenergycontroller_p.cpp
+++ b/src/bluetooth/qlowenergycontroller_p.cpp
@@ -32,6 +32,7 @@
 ****************************************************************************/
 
 #include "qlowenergycontroller_p.h"
+#include "dummy/dummy_helper_p.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -40,6 +41,7 @@ QLowEnergyControllerPrivate::QLowEnergyControllerPrivate()
       state(QLowEnergyController::UnconnectedState),
       error(QLowEnergyController::NoError)
 {
+    printDummyWarning();
     registerQLowEnergyControllerMetaType();
 }