Improve Cocoa platform plugin loading.

Loading both the debug and release version of the cocoa
plugins causes the objective-c runtime to print "duplicate
class definitions" warnings.

Fix this by directing the plugin loader to only load
one of the cocoa plugins if both are available. Implement
this as a special case directly in QFactoryLoader.

Define QT_NO_DEBUG_PLUGIN_CHECK to allow mixing
debug and release builds.

Task-number: QTBUG-28155

Change-Id: Ie1927b219cc501a821f91b7e4b56f0589e0acbf5
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/src/corelib/plugin/qfactoryloader.cpp b/src/corelib/plugin/qfactoryloader.cpp
index 75652b0902..aeb78e88b4 100644
--- a/src/corelib/plugin/qfactoryloader.cpp
+++ b/src/corelib/plugin/qfactoryloader.cpp
@@ -126,9 +126,30 @@ void QFactoryLoader::update()
 
         QStringList plugins = QDir(path).entryList(QDir::Files);
         QLibraryPrivate *library = 0;
+
+#ifdef Q_OS_MAC
+        // Loading both the debug and release version of the cocoa plugins causes the objective-c runtime
+        // to print "duplicate class definitions" warnings. Detect if QFactoryLoader is about to load both,
+        // skip one of them (below).
+        //
+        // ### FIXME find a proper solution
+        //
+        const bool isLoadingDebugAndReleaseCocoa = plugins.contains("libqcocoa_debug.dylib") && plugins.contains("libqcocoa.dylib");
+#endif
         for (int j = 0; j < plugins.count(); ++j) {
             QString fileName = QDir::cleanPath(path + QLatin1Char('/') + plugins.at(j));
 
+#ifdef Q_OS_MAC
+            if (isLoadingDebugAndReleaseCocoa) {
+#ifdef QT_DEBUG
+               if (fileName.contains(QStringLiteral("libqcocoa.dylib")))
+                   continue;    // Skip release plugin in debug mode
+#else
+               if (fileName.contains(QStringLiteral("libqcocoa_debug.dylib")))
+                   continue;    // Skip debug plugin in release mode
+#endif
+            }
+#endif
             if (qt_debug_component()) {
                 qDebug() << "QFactoryLoader::QFactoryLoader() looking at" << fileName;
             }