Fix potential symbol clash in the IIOF helpers

Since the IIOF helpers are compiled multiple times into different
handler binaries, there is a potential for symbol clash when they are
linked into the same app. Solve by enclosing the IIOF helper class in
a namespace specific to each handler.

Fixes: QTBUG-113349
Pick-to: 6.5
Change-Id: I9784d5f76d990222dba0ba12e3ca30bfaa9945cc
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
(cherry picked from commit 34282d8cef)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/plugins/imageformats/macheif/CMakeLists.txt

@@ -19,6 +19,8 @@ qt_internal_add_plugin(QMacHeifPlugin
         qmacheifhandler.cpp qmacheifhandler.h
     INCLUDE_DIRECTORIES
         ../shared
+    DEFINES
+        NS_IIOF_HELPERS=QMacHeif
     LIBRARIES
         ${FWCoreFoundation}
         ${FWCoreGraphics}

src/plugins/imageformats/macheif/main.cpp

@@ -4,7 +4,6 @@
 #ifndef QT_NO_IMAGEFORMATPLUGIN
 
 #include <qmacheifhandler.h>
-#include <qiiofhelpers_p.h>
 
 QT_BEGIN_NAMESPACE
 

src/plugins/imageformats/macheif/qmacheifhandler.cpp

@@ -2,7 +2,6 @@
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
 #include "qmacheifhandler.h"
-#include "qiiofhelpers_p.h"
 #include <QVariant>
 
 QT_BEGIN_NAMESPACE

src/plugins/imageformats/macheif/qmacheifhandler.h

@@ -6,14 +6,16 @@
 
 #include <QScopedPointer>
 #include <QImageIOHandler>
+#include "qiiofhelpers_p.h"
 
 QT_BEGIN_NAMESPACE
 
+using namespace NS_IIOF_HELPERS;
+
 class QImage;
 class QByteArray;
 class QIODevice;
 class QVariant;
-class QIIOFHelper;
 
 class QMacHeifHandler : public QImageIOHandler
 {

src/plugins/imageformats/macjp2/CMakeLists.txt

@@ -14,6 +14,8 @@ qt_internal_add_plugin(QMacJp2Plugin
         qmacjp2handler.cpp qmacjp2handler.h
     INCLUDE_DIRECTORIES
         ../shared
+    DEFINES
+        NS_IIOF_HELPERS=QMacJp2
     LIBRARIES
         ${FWCoreFoundation}
         ${FWCoreGraphics}

src/plugins/imageformats/macjp2/qmacjp2handler.cpp

@@ -7,6 +7,8 @@
 
 QT_BEGIN_NAMESPACE
 
+using namespace NS_IIOF_HELPERS;
+
 class QMacJp2HandlerPrivate
 {
     Q_DECLARE_PUBLIC(QMacJp2Handler)

src/plugins/imageformats/shared/qiiofhelpers.cpp

@@ -11,6 +11,12 @@
 
 QT_BEGIN_NAMESPACE
 
+// QImage <-> CGImage conversion functions from QtGui on darwin
+CGImageRef qt_mac_toCGImage(const QImage &qImage);
+QImage qt_mac_toQImage(CGImageRef image);
+
+namespace NS_IIOF_HELPERS {
+
 // Callbacks for sequential data provider & consumer:
 
 static size_t cbGetBytes(void *info, void *buffer, size_t count)
@@ -55,10 +61,6 @@ static size_t cbPutBytes(void *info, const void *buffer, size_t count)
 }
 
 
-// QImage <-> CGImage conversion functions from QtGui on darwin
-CGImageRef qt_mac_toCGImage(const QImage &qImage);
-QImage qt_mac_toQImage(CGImageRef image);
-
 QImageIOPlugin::Capabilities QIIOFHelpers::systemCapabilities(const QString &uti)
 {
     QImageIOPlugin::Capabilities res;
@@ -286,4 +288,6 @@ bool QIIOFHelper::writeImage(const QImage &in, const QString &uti)
     return CGImageDestinationFinalize(cgImageDest);
 }
 
+}
+
 QT_END_NAMESPACE

src/plugins/imageformats/shared/qiiofhelpers_p.h

@@ -22,6 +22,8 @@
 
 QT_BEGIN_NAMESPACE
 
+namespace NS_IIOF_HELPERS {
+
 /*
 Functions to utilize the native ImageIO Framework in OS X and iOS
 */
@@ -55,6 +57,8 @@ protected:
     QCFType<CFDictionaryRef> cfImageDict = nullptr;
 };
 
+}
+
 QT_END_NAMESPACE
 
 #endif