Use KPluginMetaData to list DataEngines

Avoid using KPluginInfo and KPluginTrader in favor of KPluginMetaData
and KPluginLoader.

Add new method that uses KPluginMetaData

Deprecate old KPluginInfo-based methods.

See also https://phabricator.kde.org/T13889

autotests/pluginloadertest.cpp

@@ -11,6 +11,7 @@
 #include <QSignalSpy>
 
 #include <KPluginInfo>
+#include <KPluginMetaData>
 
 #include <plasma/pluginloader.h>
 #include <plasma/dataengineconsumer.h>
@@ -24,7 +25,7 @@ PluginTest::PluginTest()
 
 void PluginTest::listEngines()
 {
-    KPluginInfo::List plugins = Plasma::PluginLoader::listEngineInfo();
+    QVector<KPluginMetaData> plugins = Plasma::PluginLoader::self()->listDataEngineMetaData();
 //     foreach (const KPluginInfo& info, plugins) {
         //qDebug() << " Found DataEngine: " << info.pluginName() << info.name();
 //     }

src/plasma/CMakeLists.txt

@@ -83,7 +83,7 @@ ecm_generate_export_header(KF5Plasma
     GROUP_BASE_NAME KF
     VERSION ${KF5_VERSION}
     DEPRECATED_BASE_VERSION 0
-    DEPRECATION_VERSIONS 5.6 5.19 5.28 5.30 5.36 5.46 5.67
+    DEPRECATION_VERSIONS 5.6 5.19 5.28 5.30 5.36 5.46 5.67 5.77
 )
 # TODO: add support for EXCLUDE_DEPRECATED_BEFORE_AND_AT to all Plasma libs
 # needs fixing of undeprecated API being still implemented using own deprecated API

src/plasma/pluginloader.cpp

@@ -270,10 +270,12 @@ QStringList PluginLoader::listAllEngines(const QString &parentApp)
     return engines;
 }
 
+#if PLASMA_BUILD_DEPRECATED_SINCE(5, 77)
 KPluginInfo::List PluginLoader::listEngineInfo(const QString &parentApp)
 {
     return PluginLoader::self()->listDataEngineInfo(parentApp);
 }
+#endif
 
 KPluginInfo::List PluginLoader::listEngineInfoByCategory(const QString &category, const QString &parentApp)
 {
@@ -715,21 +717,28 @@ QStringList PluginLoader::listContainmentTypes()
     return types.values();
 }
 
+#if PLASMA_BUILD_DEPRECATED_SINCE(5, 77)
 KPluginInfo::List PluginLoader::listDataEngineInfo(const QString &parentApp)
 {
-    KPluginInfo::List list;
+    return KPluginInfo::fromMetaData(listDataEngineMetaData(parentApp));
+}
+#endif
 
-    if (!d->isDefaultLoader && (parentApp.isEmpty() || parentApp == QCoreApplication::instance()->applicationName())) {
-        list = internalDataEngineInfo();
+QVector<KPluginMetaData> PluginLoader::listDataEngineMetaData(const QString &parentApp)
+{
+    auto filter = [&parentApp](const KPluginMetaData &md) -> bool
+    {
+        return md.value(QStringLiteral("X-KDE-ParentApp")) == parentApp;
+    };
+
+    QVector<KPluginMetaData> plugins;
+    if (parentApp.isEmpty()) {
+        plugins = KPluginLoader::findPlugins(PluginLoaderPrivate::s_dataEnginePluginDir);
+    } else {
+        plugins = KPluginLoader::findPlugins(PluginLoaderPrivate::s_dataEnginePluginDir, filter);
     }
 
-    QString constraint;
-    if (!parentApp.isEmpty()) {
-        constraint = QLatin1String("[X-KDE-ParentApp] == '") + parentApp + QLatin1Char('\'');
-    }
-
-    list.append(KPluginTrader::self()->query(PluginLoaderPrivate::s_dataEnginePluginDir, QStringLiteral("Plasma/DataEngine"), constraint));
-    return list;
+    return plugins;
 }
 
 KPluginInfo::List PluginLoader::listContainmentActionsInfo(const QString &parentApp)

src/plasma/pluginloader.h

@@ -73,6 +73,7 @@ public:
      */
     static QStringList listAllEngines(const QString &parentApp = QString());
 
+#if PLASMA_ENABLE_DEPRECATED_SINCE(5, 77)
     /**
      * Returns a list of all known dataengines.
      *
@@ -81,8 +82,11 @@ public:
      *                  The default value of QString() will result in a
      *                  list of all dataengines.
      * @return list of dataengines
+     * @deprecated since 5.77, use listDataEngineMetaData instead.
      **/
+    PLASMA_DEPRECATED_VERSION(5, 77, "Use listDataEngineMetaData instead")
     static KPluginInfo::List listEngineInfo(const QString &parentApp = QString());
+#endif
 
     /**
      * Returns a list of all known dataengines filtering by category.
@@ -311,6 +315,7 @@ public:
      **/
     static KPluginInfo::List listContainmentsForMimeType(const QString &mimeType);
 
+#if PLASMA_ENABLE_DEPRECATED_SINCE(5, 77)
     /**
      * Returns a list of all known dataengines.
      *
@@ -319,8 +324,23 @@ public:
      *                  The default value of QString() will result in a
      *                  list of all dataengines
      * @return list of dataengines
+     * @deprecated since 5.77, use listDataEngineMetaData()
      **/
+    PLASMA_DEPRECATED_VERSION(5, 77, "Use listDataEngineMetaData()")
     KPluginInfo::List listDataEngineInfo(const QString &parentApp = QString());
+#endif
+
+    /**
+     * Returns a list of all known dataengines.
+     *
+     * @param parentApp the application to filter dataengines on. Uses the
+     *                  X-KDE-ParentApp entry (if any) in the plugin info.
+     *                  The default value of QString() will result in a
+     *                  list of all dataengines
+     * @return list of dataengines
+     * @since 5.77
+     **/
+    QVector<KPluginMetaData> listDataEngineMetaData(const QString &parentApp = QString());
 
     /**
      * Returns a list of all known ContainmentActions.