BASE: Remove bad casts between incompatible Plugin types

Previously, a C-style cast was used to convert a
Common::Array<Plugin *>, populated with pointers to StaticPlugin
and DynamicPlugin instances, to a
Common::Array<PluginSubclass<T> *>, but PluginSubclass<T> is a
*sibling* class to StaticPlugin/DynamicPlugin, so this cast was
invalid and the results undefined. The methods for retrieving
subclasses of plugins can't be easily changed to just generate an
array of temporary wrapper objects that expose an identical API
which dereferences to the preferred PluginObject subclass because
pointers to these objects are retained by other parts of ScummVM,
so the wrappers would needed to be persisted or they would need to
just re-expose the underlying Plugin object again. This indicated
that a way to solve this problem is to have the callers receive
Plugin objects and get the PluginObject from the Plugin by
explicitly stating their desired type, in a similar manner to
std::get(std::variant), so that the pattern used by this patch to
solve the problem.

Closes gh-1051.

17 files changed, 117 insertions, 132 deletions

diff --git a/audio/mididrv.cpp b/audio/mididrv.cpp
index f053ec8440..2b7463e553 100644
--- a/audio/mididrv.cpp
+++ b/audio/mididrv.cpp
@@ -92,9 +92,9 @@ MusicType MidiDriver::getMusicType(MidiDriver::DeviceHandle handle) {
 		return MT_MT32;
 
 	if (handle) {
-		const MusicPlugin::List p = MusicMan.getPlugins();
-		for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end(); m++) {
-			MusicDevices i = (**m)->getDevices();
+		const PluginList p = MusicMan.getPlugins();
+		for (PluginList::const_iterator m = p.begin(); m != p.end(); m++) {
+			MusicDevices i = (*m)->get<MusicPluginObject>().getDevices();
 			for (MusicDevices::iterator d = i.begin(); d != i.end(); d++) {
 				if (handle == d->getHandle())
 					return d->getMusicType();
@@ -107,9 +107,9 @@ MusicType MidiDriver::getMusicType(MidiDriver::DeviceHandle handle) {
 
 Common::String MidiDriver::getDeviceString(DeviceHandle handle, DeviceStringType type) {
 	if (handle) {
-		const MusicPlugin::List p = MusicMan.getPlugins();
-		for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end(); m++) {
-			MusicDevices i = (**m)->getDevices();
+		const PluginList p = MusicMan.getPlugins();
+		for (PluginList::const_iterator m = p.begin(); m != p.end(); m++) {
+			MusicDevices i = (*m)->get<MusicPluginObject>().getDevices();
 			for (MusicDevices::iterator d = i.begin(); d != i.end(); d++) {
 				if (handle == d->getHandle()) {
 					if (type == kDriverName)
@@ -226,7 +226,7 @@ MidiDriver::DeviceHandle MidiDriver::detectDevice(int flags) {
 
 	// If the selected driver did not match the flags setting,
 	// we try to determine a suitable and "optimal" music driver.
-	const MusicPlugin::List p = MusicMan.getPlugins();
+	const PluginList p = MusicMan.getPlugins();
 	// If only MDT_MIDI but not MDT_PREFER_MT32 or MDT_PREFER_GM is set we prefer the other devices (which will always be
 	// detected since they are hard coded and cannot be disabled).
 	bool skipMidi = !(flags & (MDT_PREFER_GM | MDT_PREFER_MT32));
@@ -280,8 +280,8 @@ MidiDriver::DeviceHandle MidiDriver::detectDevice(int flags) {
 				// and there is no preferred MT32 or GM device selected either or if the detected device is unavailable we arrive here.
 				// If MT32 is preferred we try for the first available device with music type 'MT_MT32' (usually the mt32 emulator).
 				if (flags & MDT_PREFER_MT32) {
-					for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end(); ++m) {
-						MusicDevices i = (**m)->getDevices();
+					for (PluginList::const_iterator m = p.begin(); m != p.end(); ++m) {
+						MusicDevices i = (*m)->get<MusicPluginObject>().getDevices();
 						for (MusicDevices::iterator d = i.begin(); d != i.end(); ++d) {
 							if (d->getMusicType() == MT_MT32) {
 								hdl = d->getHandle();
@@ -295,8 +295,8 @@ MidiDriver::DeviceHandle MidiDriver::detectDevice(int flags) {
 				// Now we default to the first available device with music type 'MT_GM' if not
 				// MT-32 is preferred or if MT-32 is preferred but all other devices have failed.
 				if (!(flags & MDT_PREFER_MT32) || flags == (MDT_PREFER_MT32 | MDT_MIDI)) {
-					for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end(); ++m) {
-						MusicDevices i = (**m)->getDevices();
+					for (PluginList::const_iterator m = p.begin(); m != p.end(); ++m) {
+						MusicDevices i = (*m)->get<MusicPluginObject>().getDevices();
 						for (MusicDevices::iterator d = i.begin(); d != i.end(); ++d) {
 							if (d->getMusicType() == MT_GM || d->getMusicType() == MT_GS) {
 								hdl = d->getHandle();
@@ -348,8 +348,8 @@ MidiDriver::DeviceHandle MidiDriver::detectDevice(int flags) {
 			tp = MT_AUTO;
 		}
 
-		for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end(); ++m) {
-			MusicDevices i = (**m)->getDevices();
+		for (PluginList::const_iterator m = p.begin(); m != p.end(); ++m) {
+			MusicDevices i = (*m)->get<MusicPluginObject>().getDevices();
 			for (MusicDevices::iterator d = i.begin(); d != i.end(); ++d) {
 				if (d->getMusicType() == tp) {
 					hdl = d->getHandle();
@@ -365,33 +365,35 @@ MidiDriver::DeviceHandle MidiDriver::detectDevice(int flags) {
 
 MidiDriver *MidiDriver::createMidi(MidiDriver::DeviceHandle handle) {
 	MidiDriver *driver = 0;
-	const MusicPlugin::List p = MusicMan.getPlugins();
-	for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end(); m++) {
-		if (getDeviceString(handle, MidiDriver::kDriverId).equals((**m)->getId()))
-			(**m)->createInstance(&driver, handle);
+	const PluginList p = MusicMan.getPlugins();
+	for (PluginList::const_iterator m = p.begin(); m != p.end(); m++) {
+		const MusicPluginObject &musicPlugin = (*m)->get<MusicPluginObject>();
+		if (getDeviceString(handle, MidiDriver::kDriverId).equals(musicPlugin.getId()))
+			musicPlugin.createInstance(&driver, handle);
 	}
 
 	return driver;
 }
 
 bool MidiDriver::checkDevice(MidiDriver::DeviceHandle handle) {
-	const MusicPlugin::List p = MusicMan.getPlugins();
-	for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end(); m++) {
-		if (getDeviceString(handle, MidiDriver::kDriverId).equals((**m)->getId()))
-			return (**m)->checkDevice(handle);
+	const PluginList p = MusicMan.getPlugins();
+	for (PluginList::const_iterator m = p.begin(); m != p.end(); m++) {
+		const MusicPluginObject &musicPlugin = (*m)->get<MusicPluginObject>();
+		if (getDeviceString(handle, MidiDriver::kDriverId).equals(musicPlugin.getId()))
+			return musicPlugin.checkDevice(handle);
 	}
 
 	return false;
 }
 
 MidiDriver::DeviceHandle MidiDriver::getDeviceHandle(const Common::String &identifier) {
-	const MusicPlugin::List p = MusicMan.getPlugins();
+	const PluginList p = MusicMan.getPlugins();
 
 	if (p.begin() == p.end())
 		error("MidiDriver::getDeviceHandle: Music plugins must be loaded prior to calling this method");
 
-	for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end(); m++) {
-		MusicDevices i = (**m)->getDevices();
+	for (PluginList::const_iterator m = p.begin(); m != p.end(); m++) {
+		MusicDevices i = (*m)->get<MusicPluginObject>().getDevices();
 		for (MusicDevices::iterator d = i.begin(); d != i.end(); d++) {
 			// The music driver id isn't unique, but it will match
 			// driver's first device. This is useful when selecting
diff --git a/audio/musicplugin.h b/audio/musicplugin.h
index 849d3f92cd..b83e93a445 100644
--- a/audio/musicplugin.h
+++ b/audio/musicplugin.h
@@ -112,11 +112,6 @@ public:
 	virtual Common::Error createInstance(MidiDriver **mididriver, MidiDriver::DeviceHandle = 0) const = 0;
 };
 
-
-// Music plugins
-
-typedef PluginSubclass<MusicPluginObject> MusicPlugin;
-
 /**
  * Singleton class which manages all Music plugins.
  */
@@ -125,7 +120,7 @@ private:
 	friend class Common::Singleton<SingletonBaseType>;
 
 public:
-	const MusicPlugin::List &getPlugins() const;
+	const PluginList &getPlugins() const;
 };
 
 /** Convenience shortcut for accessing the Music manager. */
diff --git a/base/commandLine.cpp b/base/commandLine.cpp
index 640daa1793..2e981fb75a 100644
--- a/base/commandLine.cpp
+++ b/base/commandLine.cpp
@@ -673,9 +673,9 @@ static void listGames() {
 	printf("Game ID              Full Title                                            \n"
 	       "-------------------- ------------------------------------------------------\n");
 
-	const EnginePlugin::List &plugins = EngineMan.getPlugins();
-	for (EnginePlugin::List::const_iterator iter = plugins.begin(); iter != plugins.end(); ++iter) {
-		GameList list = (**iter)->getSupportedGames();
+	const PluginList &plugins = EngineMan.getPlugins();
+	for (PluginList::const_iterator iter = plugins.begin(); iter != plugins.end(); ++iter) {
+		GameList list = (*iter)->get<MetaEngine>().getSupportedGames();
 		for (GameList::iterator v = list.begin(); v != list.end(); ++v) {
 			printf("%-20s %s\n", v->gameid().c_str(), v->description().c_str());
 		}
@@ -741,7 +741,7 @@ static Common::Error listSaves(const char *target) {
 	gameid.toLowercase();	// Normalize it to lower case
 
 	// Find the plugin that will handle the specified gameid
-	const EnginePlugin *plugin = 0;
+	const Plugin *plugin = nullptr;
 	GameDescriptor game = EngineMan.findGame(gameid, &plugin);
 
 	if (!plugin) {
@@ -749,13 +749,15 @@ static Common::Error listSaves(const char *target) {
 						Common::String::format("target '%s', gameid '%s", target, gameid.c_str()));
 	}
 
-	if (!(*plugin)->hasFeature(MetaEngine::kSupportsListSaves)) {
+	const MetaEngine &metaEngine = plugin->get<MetaEngine>();
+
+	if (!metaEngine.hasFeature(MetaEngine::kSupportsListSaves)) {
 		// TODO: Include more info about the target (desc, engine name, ...) ???
 		return Common::Error(Common::kEnginePluginNotSupportSaves,
 						Common::String::format("target '%s', gameid '%s", target, gameid.c_str()));
 	} else {
 		// Query the plugin for a list of saved games
-		SaveStateList saveList = (*plugin)->listSaves(target);
+		SaveStateList saveList = metaEngine.listSaves(target);
 
 		if (saveList.size() > 0) {
 			// TODO: Include more info about the target (desc, engine name, ...) ???
@@ -793,13 +795,14 @@ static void listThemes() {
 
 /** Lists all output devices */
 static void listAudioDevices() {
-	MusicPlugin::List pluginList = MusicMan.getPlugins();
+	PluginList pluginList = MusicMan.getPlugins();
 
 	printf("ID                             Description\n");
 	printf("------------------------------ ------------------------------------------------\n");
 
-	for (MusicPlugin::List::const_iterator i = pluginList.begin(), iend = pluginList.end(); i != iend; ++i) {
-		MusicDevices deviceList = (**i)->getDevices();
+	for (PluginList::const_iterator i = pluginList.begin(), iend = pluginList.end(); i != iend; ++i) {
+		const MusicPluginObject &musicObject = (*i)->get<MusicPluginObject>();
+		MusicDevices deviceList = musicObject.getDevices();
 		for (MusicDevices::iterator j = deviceList.begin(), jend = deviceList.end(); j != jend; ++j) {
 			printf("%-30s %s\n", Common::String::format("\"%s\"", j->getCompleteId().c_str()).c_str(), j->getCompleteName().c_str());
 		}
diff --git a/base/main.cpp b/base/main.cpp
index 4251c2c678..f529f3ec08 100644
--- a/base/main.cpp
+++ b/base/main.cpp
@@ -106,8 +106,8 @@ static bool launcherDialog() {
 	return (dlg.runModal() != -1);
 }
 
-static const EnginePlugin *detectPlugin() {
-	const EnginePlugin *plugin = 0;
+static const Plugin *detectPlugin() {
+	const Plugin *plugin = nullptr;
 
 	// Make sure the gameid is set in the config manager, and that it is lowercase.
 	Common::String gameid(ConfMan.getActiveDomainName());
@@ -141,7 +141,7 @@ static const EnginePlugin *detectPlugin() {
 }
 
 // TODO: specify the possible return values here
-static Common::Error runGame(const EnginePlugin *plugin, OSystem &system, const Common::String &edebuglevels) {
+static Common::Error runGame(const Plugin *plugin, OSystem &system, const Common::String &edebuglevels) {
 	// Determine the game data path, for validation and error messages
 	Common::FSNode dir(ConfMan.get("path"));
 	Common::Error err = Common::kNoError;
@@ -169,15 +169,16 @@ static Common::Error runGame(const EnginePlugin *plugin, OSystem &system, const
 
 	// Create the game engine
 	if (err.getCode() == Common::kNoError) {
+		const MetaEngine &metaEngine = plugin->get<MetaEngine>();
 		// Set default values for all of the custom engine options
 		// Appareantly some engines query them in their constructor, thus we
 		// need to set this up before instance creation.
-		const ExtraGuiOptions engineOptions = (*plugin)->getExtraGuiOptions(Common::String());
+		const ExtraGuiOptions engineOptions = metaEngine.getExtraGuiOptions(Common::String());
 		for (uint i = 0; i < engineOptions.size(); i++) {
 			ConfMan.registerDefault(engineOptions[i].configOption, engineOptions[i].defaultState);
 		}
 
-		err = (*plugin)->createInstance(&system, &engine);
+		err = metaEngine.createInstance(&system, &engine);
 	}
 
 	// Check for errors
@@ -504,7 +505,7 @@ extern "C" int scummvm_main(int argc, const char * const argv[]) {
 	// cleanly, so this is now enabled to encourage people to fix bits :)
 	while (0 != ConfMan.getActiveDomain()) {
 		// Try to find a plugin which feels responsible for the specified game.
-		const EnginePlugin *plugin = detectPlugin();
+		const Plugin *plugin = detectPlugin();
 		if (plugin) {
 			// Unload all plugins not needed for this game,
 			// to save memory
diff --git a/base/plugins.cpp b/base/plugins.cpp
index 39aaf2f73e..18755003b4 100644
--- a/base/plugins.cpp
+++ b/base/plugins.cpp
@@ -457,7 +457,7 @@ DECLARE_SINGLETON(EngineManager);
  * For the uncached version, we first try to find the plugin using the gameId
  * and only if we can't find it there, we loop through the plugins.
  **/
-GameDescriptor EngineManager::findGame(const Common::String &gameName, const EnginePlugin **plugin) const {
+GameDescriptor EngineManager::findGame(const Common::String &gameName, const Plugin **plugin) const {
 	GameDescriptor result;
 
 	// First look for the game using the plugins in memory. This is critical
@@ -493,18 +493,18 @@ GameDescriptor EngineManager::findGame(const Common::String &gameName, const Eng
 /**
  * Find the game within the plugins loaded in memory
  **/
-GameDescriptor EngineManager::findGameInLoadedPlugins(const Common::String &gameName, const EnginePlugin **plugin) const {
+GameDescriptor EngineManager::findGameInLoadedPlugins(const Common::String &gameName, const Plugin **plugin) const {
 	// Find the GameDescriptor for this target
-	const EnginePlugin::List &plugins = getPlugins();
+	const PluginList &plugins = getPlugins();
 	GameDescriptor result;
 
 	if (plugin)
 		*plugin = 0;
 
-	EnginePlugin::List::const_iterator iter;
+	PluginList::const_iterator iter;
 
 	for (iter = plugins.begin(); iter != plugins.end(); ++iter) {
-		result = (**iter)->findGame(gameName.c_str());
+		result = (*iter)->get<MetaEngine>().findGame(gameName.c_str());
 		if (!result.gameid().empty()) {
 			if (plugin)
 				*plugin = *iter;
@@ -516,22 +516,22 @@ GameDescriptor EngineManager::findGameInLoadedPlugins(const Common::String &game
 
 GameList EngineManager::detectGames(const Common::FSList &fslist) const {
 	GameList candidates;
-	EnginePlugin::List plugins;
-	EnginePlugin::List::const_iterator iter;
+	PluginList plugins;
+	PluginList::const_iterator iter;
 	PluginManager::instance().loadFirstPlugin();
 	do {
 		plugins = getPlugins();
 		// Iterate over all known games and for each check if it might be
 		// the game in the presented directory.
 		for (iter = plugins.begin(); iter != plugins.end(); ++iter) {
-			candidates.push_back((**iter)->detectGames(fslist));
+			candidates.push_back((*iter)->get<MetaEngine>().detectGames(fslist));
 		}
 	} while (PluginManager::instance().loadNextPlugin());
 	return candidates;
 }
 
-const EnginePlugin::List &EngineManager::getPlugins() const {
-	return (const EnginePlugin::List &)PluginManager::instance().getPlugins(PLUGIN_TYPE_ENGINE);
+const PluginList &EngineManager::getPlugins() const {
+	return PluginManager::instance().getPlugins(PLUGIN_TYPE_ENGINE);
 }
 
 
@@ -543,6 +543,6 @@ namespace Common {
 DECLARE_SINGLETON(MusicManager);
 }
 
-const MusicPlugin::List &MusicManager::getPlugins() const {
-	return (const MusicPlugin::List &)PluginManager::instance().getPlugins(PLUGIN_TYPE_MUSIC);
+const PluginList &MusicManager::getPlugins() const {
+	return PluginManager::instance().getPlugins(PLUGIN_TYPE_MUSIC);
 }
diff --git a/base/plugins.h b/base/plugins.h
index 2793ff3ffd..ce45f7102a 100644
--- a/base/plugins.h
+++ b/base/plugins.h
@@ -190,6 +190,15 @@ public:
 	PluginType getType() const;
 	const char *getName() const;
 
+	template <class T>
+	T &get() const {
+		T *pluginObject = dynamic_cast<T *>(_pluginObject);
+		if (!pluginObject) {
+			error("Invalid cast of plugin %s", getName());
+		}
+		return *pluginObject;
+	}
+
 	/**
 	 * The getFileName() function gets the name of the plugin file for those
 	 * plugins that have files (ie. not static). It doesn't require the plugin
@@ -202,25 +211,6 @@ public:
 typedef Common::Array<Plugin *> PluginList;
 
 /**
- * Convenience template to make it easier defining normal Plugin
- * subclasses. Namely, the PluginSubclass will manage PluginObjects
- * of a type specified via the PO_t template parameter.
- */
-template<class PO_t>
-class PluginSubclass : public Plugin {
-public:
-	PO_t &operator*() const {
-		return *(PO_t *)_pluginObject;
-	}
-
-	PO_t *operator->() const {
-		return (PO_t *)_pluginObject;
-	}
-
-	typedef Common::Array<PluginSubclass *> List;
-};
-
-/**
  * Abstract base class for Plugin factories. Subclasses of this
  * are responsible for creating plugin objects, e.g. by loading
  * loadable modules from storage media; by creating "fake" plugins
diff --git a/engines/metaengine.h b/engines/metaengine.h
index 568b66ac51..b3aaa96a8f 100644
--- a/engines/metaengine.h
+++ b/engines/metaengine.h
@@ -262,20 +262,15 @@ public:
 	//@}
 };
 
-
-// Engine plugins
-
-typedef PluginSubclass<MetaEngine> EnginePlugin;
-
 /**
  * Singleton class which manages all Engine plugins.
  */
 class EngineManager : public Common::Singleton<EngineManager> {
 public:
-	GameDescriptor findGameInLoadedPlugins(const Common::String &gameName, const EnginePlugin **plugin = NULL) const;
-	GameDescriptor findGame(const Common::String &gameName, const EnginePlugin **plugin = NULL) const;
+	GameDescriptor findGameInLoadedPlugins(const Common::String &gameName, const Plugin **plugin = NULL) const;
+	GameDescriptor findGame(const Common::String &gameName, const Plugin **plugin = NULL) const;
 	GameList detectGames(const Common::FSList &fslist) const;
-	const EnginePlugin::List &getPlugins() const;
+	const PluginList &getPlugins() const;
 };
 
 /** Convenience shortcut for accessing the engine manager. */
diff --git a/engines/neverhood/menumodule.cpp b/engines/neverhood/menumodule.cpp
index e58dd31f03..e3996a2507 100644
--- a/engines/neverhood/menumodule.cpp
+++ b/engines/neverhood/menumodule.cpp
@@ -870,7 +870,7 @@ void SavegameListBox::pageDown() {
 }
 
 int GameStateMenu::scummVMSaveLoadDialog(bool isSave, Common::String &saveDesc) {
-	const EnginePlugin *plugin = NULL;
+	const Plugin *plugin = nullptr;
 	EngineMan.findGame(ConfMan.get("gameid"), &plugin);
 	GUI::SaveLoadChooser *dialog;
 	Common::String desc;
diff --git a/engines/pegasus/pegasus.cpp b/engines/pegasus/pegasus.cpp
index 5f756449dd..f2c0afba5c 100644
--- a/engines/pegasus/pegasus.cpp
+++ b/engines/pegasus/pegasus.cpp
@@ -356,7 +356,7 @@ Common::Error PegasusEngine::showLoadDialog() {
 
 	Common::String gameId = ConfMan.get("gameid");
 
-	const EnginePlugin *plugin = 0;
+	const Plugin *plugin = nullptr;
 	EngineMan.findGame(gameId, &plugin);
 
 	int slot = slc.runModalWithPluginAndTarget(plugin, ConfMan.getActiveDomainName());
@@ -380,7 +380,7 @@ Common::Error PegasusEngine::showSaveDialog() {
 
 	Common::String gameId = ConfMan.get("gameid");
 
-	const EnginePlugin *plugin = 0;
+	const Plugin *plugin = nullptr;
 	EngineMan.findGame(gameId, &plugin);
 
 	int slot = slc.runModalWithPluginAndTarget(plugin, ConfMan.getActiveDomainName());
diff --git a/gui/EventRecorder.cpp b/gui/EventRecorder.cpp
index f1b486d394..39811513e3 100644
--- a/gui/EventRecorder.cpp
+++ b/gui/EventRecorder.cpp
@@ -598,8 +598,7 @@ void EventRecorder::setFileHeader() {
 		return;
 	}
 	TimeDate t;
-	const EnginePlugin *plugin = 0;
-	GameDescriptor desc = EngineMan.findGame(ConfMan.getActiveDomainName(), &plugin);
+	GameDescriptor desc = EngineMan.findGame(ConfMan.getActiveDomainName());
 	g_system->getTimeAndDate(t);
 	if (_author.empty()) {
 		setAuthor("Unknown Author");
@@ -619,19 +618,19 @@ SDL_Surface *EventRecorder::getSurface(int width, int height) {
 
 bool EventRecorder::switchMode() {
 	const Common::String gameId = ConfMan.get("gameid");
-	const EnginePlugin *plugin = 0;
+	const Plugin *plugin = nullptr;
 	EngineMan.findGame(gameId, &plugin);
-	bool metaInfoSupport = (*plugin)->hasFeature(MetaEngine::kSavesSupportMetaInfo);
+	bool metaInfoSupport = plugin->get<MetaEngine>().hasFeature(MetaEngine::kSavesSupportMetaInfo);
 	bool featuresSupport = metaInfoSupport &&
 						  g_engine->canSaveGameStateCurrently() &&
-						  (*plugin)->hasFeature(MetaEngine::kSupportsListSaves) &&
-						  (*plugin)->hasFeature(MetaEngine::kSupportsDeleteSave);
+						  plugin->get<MetaEngine>().hasFeature(MetaEngine::kSupportsListSaves) &&
+						  plugin->get<MetaEngine>().hasFeature(MetaEngine::kSupportsDeleteSave);
 	if (!featuresSupport) {
 		return false;
 	}
 
 	int emptySlot = 1;
-	SaveStateList saveList = (*plugin)->listSaves(gameId.c_str());
+	SaveStateList saveList = plugin->get<MetaEngine>().listSaves(gameId.c_str());
 	for (SaveStateList::const_iterator x = saveList.begin(); x != saveList.end(); ++x) {
 		int saveSlot = x->getSaveSlot();
 		if (saveSlot == 0) {
@@ -667,9 +666,9 @@ bool EventRecorder::checkForContinueGame() {
 void EventRecorder::deleteTemporarySave() {
 	if (_temporarySlot == -1) return;
 	const Common::String gameId = ConfMan.get("gameid");
-	const EnginePlugin *plugin = 0;
+	const Plugin *plugin = 0;
 	EngineMan.findGame(gameId, &plugin);
-	 (*plugin)->removeSaveState(gameId.c_str(), _temporarySlot);
+	 plugin->get<MetaEngine>().removeSaveState(gameId.c_str(), _temporarySlot);
 	_temporarySlot = -1;
 }
 
diff --git a/gui/about.cpp b/gui/about.cpp
index bde5db310a..25912557f9 100644
--- a/gui/about.cpp
+++ b/gui/about.cpp
@@ -110,16 +110,16 @@ AboutDialog::AboutDialog()
 	engines += _("Available engines:");
 	addLine(engines.c_str());
 
-	const EnginePlugin::List &plugins = EngineMan.getPlugins();
-	EnginePlugin::List::const_iterator iter = plugins.begin();
+	const PluginList &plugins = EngineMan.getPlugins();
+	PluginList::const_iterator iter = plugins.begin();
 	for (; iter != plugins.end(); ++iter) {
 		Common::String str;
 		str = "C0";
-		str += (**iter).getName();
+		str += (*iter)->getName();
 		addLine(str.c_str());
 
 		str = "C2";
-		str += (**iter)->getOriginalCopyright();
+		str += (*iter)->get<MetaEngine>().getOriginalCopyright();
 		addLine(str.c_str());
 
 		//addLine("");
diff --git a/gui/editgamedialog.cpp b/gui/editgamedialog.cpp
index 94c74b40c0..348ba5cb91 100644
--- a/gui/editgamedialog.cpp
+++ b/gui/editgamedialog.cpp
@@ -97,7 +97,7 @@ protected:
 EditGameDialog::EditGameDialog(const String &domain, const String &desc)
 	: OptionsDialog(domain, "GameOptions") {
 	// Retrieve all game specific options.
-	const EnginePlugin *plugin = 0;
+	const Plugin *plugin = nullptr;
 	// To allow for game domains without a gameid.
 	// TODO: Is it intentional that this is still supported?
 	String gameId(ConfMan.get("gameid", domain));
@@ -107,7 +107,7 @@ EditGameDialog::EditGameDialog(const String &domain, const String &desc)
 	// implementation.
 	EngineMan.findGame(gameId, &plugin);
 	if (plugin) {
-		_engineOptions = (*plugin)->getExtraGuiOptions(domain);
+		_engineOptions = plugin->get<MetaEngine>().getExtraGuiOptions(domain);
 	} else {
 		warning("Plugin for target \"%s\" not found! Game specific settings might be missing", domain.c_str());
 	}
diff --git a/gui/launcher.cpp b/gui/launcher.cpp
index 3ed1236a91..fd75674300 100644
--- a/gui/launcher.cpp
+++ b/gui/launcher.cpp
@@ -504,7 +504,7 @@ void LauncherDialog::loadGame(int item) {
 	if (gameId.empty())
 		gameId = _domains[item];
 
-	const EnginePlugin *plugin = 0;
+	const Plugin *plugin = nullptr;
 
 	EngineMan.findGame(gameId, &plugin);
 
@@ -512,8 +512,9 @@ void LauncherDialog::loadGame(int item) {
 	target.toLowercase();
 
 	if (plugin) {
-		if ((*plugin)->hasFeature(MetaEngine::kSupportsListSaves) &&
-			(*plugin)->hasFeature(MetaEngine::kSupportsLoadingDuringStartup)) {
+		const MetaEngine &metaEngine = plugin->get<MetaEngine>();
+		if (metaEngine.hasFeature(MetaEngine::kSupportsListSaves) &&
+			metaEngine.hasFeature(MetaEngine::kSupportsLoadingDuringStartup)) {
 			int slot = _loadDialog->runModalWithPluginAndTarget(plugin, target);
 			if (slot >= 0) {
 				ConfMan.setActiveDomain(_domains[item]);
diff --git a/gui/options.cpp b/gui/options.cpp
index 82eb252cf1..f1ca21a90d 100644
--- a/gui/options.cpp
+++ b/gui/options.cpp
@@ -1040,9 +1040,9 @@ void OptionsDialog::addAudioControls(GuiObject *boss, const Common::String &pref
 	const Common::String allFlags = MidiDriver::musicType2GUIO((uint32)-1);
 	bool hasMidiDefined = (strpbrk(_guioptions.c_str(), allFlags.c_str()) != NULL);
 
-	const MusicPlugin::List p = MusicMan.getPlugins();
-	for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end(); ++m) {
-		MusicDevices i = (**m)->getDevices();
+	const PluginList p = MusicMan.getPlugins();
+	for (PluginList::const_iterator m = p.begin(); m != p.end(); ++m) {
+		MusicDevices i = (*m)->get<MusicPluginObject>().getDevices();
 		for (MusicDevices::iterator d = i.begin(); d != i.end(); ++d) {
 			Common::String deviceGuiOption = MidiDriver::musicType2GUIO(d->getMusicType());
 
@@ -1078,19 +1078,19 @@ void OptionsDialog::addMIDIControls(GuiObject *boss, const Common::String &prefi
 	_gmDevicePopUp = new PopUpWidget(boss, prefix + "auPrefGmPopup");
 
 	// Populate
-	const MusicPlugin::List p = MusicMan.getPlugins();
+	const PluginList p = MusicMan.getPlugins();
 	// Make sure the null device is the first one in the list to avoid undesired
 	// auto detection for users who don't have a saved setting yet.
-	for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end(); ++m) {
-		MusicDevices i = (**m)->getDevices();
+	for (PluginList::const_iterator m = p.begin(); m != p.end(); ++m) {
+		MusicDevices i = (*m)->get<MusicPluginObject>().getDevices();
 		for (MusicDevices::iterator d = i.begin(); d != i.end(); ++d) {
 			if (d->getMusicDriverId() == "null")
 				_gmDevicePopUp->appendEntry(_("Don't use General MIDI music"), d->getHandle());
 		}
 	}
 	// Now we add the other devices.
-	for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end(); ++m) {
-		MusicDevices i = (**m)->getDevices();
+	for (PluginList::const_iterator m = p.begin(); m != p.end(); ++m) {
+		MusicDevices i = (*m)->get<MusicPluginObject>().getDevices();
 		for (MusicDevices::iterator d = i.begin(); d != i.end(); ++d) {
 			if (d->getMusicType() >= MT_GM) {
 				if (d->getMusicType() != MT_MT32)
@@ -1141,19 +1141,19 @@ void OptionsDialog::addMT32Controls(GuiObject *boss, const Common::String &prefi
 	// GS Extensions setting
 	_enableGSCheckbox = new CheckboxWidget(boss, prefix + "mcGSCheckbox", _("Roland GS Device (enable MT-32 mappings)"), _("Check if you want to enable patch mappings to emulate an MT-32 on a Roland GS device"));
 
-	const MusicPlugin::List p = MusicMan.getPlugins();
+	const PluginList p = MusicMan.getPlugins();
 	// Make sure the null device is the first one in the list to avoid undesired
 	// auto detection for users who don't have a saved setting yet.
-	for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end(); ++m) {
-		MusicDevices i = (**m)->getDevices();
+	for (PluginList::const_iterator m = p.begin(); m != p.end(); ++m) {
+		MusicDevices i = (*m)->get<MusicPluginObject>().getDevices();
 		for (MusicDevices::iterator d = i.begin(); d != i.end(); ++d) {
 			if (d->getMusicDriverId() == "null")
 				_mt32DevicePopUp->appendEntry(_("Don't use Roland MT-32 music"), d->getHandle());
 		}
 	}
 	// Now we add the other devices.
-	for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end(); ++m) {
-		MusicDevices i = (**m)->getDevices();
+	for (PluginList::const_iterator m = p.begin(); m != p.end(); ++m) {
+		MusicDevices i = (*m)->get<MusicPluginObject>().getDevices();
 		for (MusicDevices::iterator d = i.begin(); d != i.end(); ++d) {
 			if (d->getMusicType() >= MT_GM)
 				_mt32DevicePopUp->appendEntry(d->getCompleteName(), d->getHandle());
@@ -1265,10 +1265,10 @@ bool OptionsDialog::loadMusicDeviceSetting(PopUpWidget *popup, Common::String se
 
 	if (_domain != Common::ConfigManager::kApplicationDomain || ConfMan.hasKey(setting, _domain) || preferredType) {
 		const Common::String drv = ConfMan.get(setting, (_domain != Common::ConfigManager::kApplicationDomain && !ConfMan.hasKey(setting, _domain)) ? Common::ConfigManager::kApplicationDomain : _domain);
-		const MusicPlugin::List p = MusicMan.getPlugins();
+		const PluginList p = MusicMan.getPlugins();
 
-		for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end(); ++m) {
-			MusicDevices i = (**m)->getDevices();
+		for (PluginList::const_iterator m = p.begin(); m != p.end(); ++m) {
+			MusicDevices i = (*m)->get<MusicPluginObject>().getDevices();
 			for (MusicDevices::iterator d = i.begin(); d != i.end(); ++d) {
 				if (setting.empty() ? (preferredType == d->getMusicType()) : (drv == d->getCompleteId())) {
 					popup->setSelectedTag(d->getHandle());
@@ -1285,10 +1285,10 @@ void OptionsDialog::saveMusicDeviceSetting(PopUpWidget *popup, Common::String se
 	if (!popup || !_enableAudioSettings)
 		return;
 
-	const MusicPlugin::List p = MusicMan.getPlugins();
+	const PluginList p = MusicMan.getPlugins();
 	bool found = false;
-	for (MusicPlugin::List::const_iterator m = p.begin(); m != p.end() && !found; ++m) {
-		MusicDevices i = (**m)->getDevices();
+	for (PluginList::const_iterator m = p.begin(); m != p.end() && !found; ++m) {
+		MusicDevices i = (*m)->get<MusicPluginObject>().getDevices();
 		for (MusicDevices::iterator d = i.begin(); d != i.end(); ++d) {
 			if (d->getHandle() == popup->getSelectedTag()) {
 				ConfMan.set(setting, d->getCompleteId(), _domain);
diff --git a/gui/recorderdialog.cpp b/gui/recorderdialog.cpp
index c08b3e149a..7e8e12bcf8 100644
--- a/gui/recorderdialog.cpp
+++ b/gui/recorderdialog.cpp
@@ -167,8 +167,7 @@ void RecorderDialog::handleCommand(CommandSender *sender, uint32 cmd, uint32 dat
 	case kRecordCmd: {
 		TimeDate t;
 		Common::String gameId = ConfMan.get("gameid", _target);
-		const EnginePlugin *plugin = 0;
-		GameDescriptor desc = EngineMan.findGame(gameId, &plugin);
+		GameDescriptor desc = EngineMan.findGame(gameId);
 		g_system->getTimeAndDate(t);
 		EditRecordDialog editDlg(_("Unknown Author"), Common::String::format("%.2d.%.2d.%.4d ", t.tm_mday, t.tm_mon, 1900 + t.tm_year) + desc.description(), "");
 		if (editDlg.runModal() != kOKCmd) {
diff --git a/gui/saveload.cpp b/gui/saveload.cpp
index ba17dacc48..a893f3c0db 100644
--- a/gui/saveload.cpp
+++ b/gui/saveload.cpp
@@ -76,14 +76,14 @@ Common::String SaveLoadChooser::createDefaultSaveDescription(const int slot) con
 int SaveLoadChooser::runModalWithCurrentTarget() {
 	const Common::String gameId = ConfMan.get("gameid");
 
-	const EnginePlugin *plugin = 0;
+	const Plugin *plugin = 0;
 	EngineMan.findGame(gameId, &plugin);
 
 	return runModalWithPluginAndTarget(plugin, ConfMan.getActiveDomainName());
 }
 
-int SaveLoadChooser::runModalWithPluginAndTarget(const EnginePlugin *plugin, const String &target) {
-	selectChooser(**plugin);
+int SaveLoadChooser::runModalWithPluginAndTarget(const Plugin *plugin, const String &target) {
+	selectChooser(plugin->get<MetaEngine>());
 	if (!_impl)
 		return -1;
 
@@ -98,10 +98,10 @@ int SaveLoadChooser::runModalWithPluginAndTarget(const EnginePlugin *plugin, con
 
 	int ret;
 	do {
-		ret = _impl->run(target, &(**plugin));
+		ret = _impl->run(target, &plugin->get<MetaEngine>());
 #ifndef DISABLE_SAVELOADCHOOSER_GRID
 		if (ret == kSwitchSaveLoadDialog) {
-			selectChooser(**plugin);
+			selectChooser(plugin->get<MetaEngine>());
 		}
 #endif // !DISABLE_SAVELOADCHOOSER_GRID
 	} while (ret < -1);
diff --git a/gui/saveload.h b/gui/saveload.h
index 01a78c4924..be0bc4206f 100644
--- a/gui/saveload.h
+++ b/gui/saveload.h
@@ -51,7 +51,7 @@ public:
 	 * @return The selcted save slot. -1 in case none is selected.
 	 */
 	int runModalWithCurrentTarget();
-	int runModalWithPluginAndTarget(const EnginePlugin *plugin, const String &target);
+	int runModalWithPluginAndTarget(const Plugin *plugin, const String &target);
 
 	const Common::String &getResultString() const;