Allow QML plugins to be optional

If a plugin does nothing but load the library that provides the types,
we can skip the plugin loading by linking the library directly. State
that in the qmldir file, and evaluate it when loading the module.

Task-number: QTBUG-84639
Change-Id: I2097237866a50f66c55e4653ad119fe10e18a893
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

9 files changed, 127 insertions, 5 deletions

diff --git a/tests/auto/qml/qqmlmoduleplugin/CMakeLists.txt b/tests/auto/qml/qqmlmoduleplugin/CMakeLists.txt
index d0aa1a9aa9..2fcce3d7c9 100644
--- a/tests/auto/qml/qqmlmoduleplugin/CMakeLists.txt
+++ b/tests/auto/qml/qqmlmoduleplugin/CMakeLists.txt
@@ -30,6 +30,7 @@ qt_add_test(tst_qqmlmoduleplugin
         Qt::GuiPrivate
         Qt::Network
         Qt::QmlPrivate
+        Qt::QuickShapesPrivate
     TESTDATA ${test_data}
 )
 
@@ -107,3 +108,4 @@ add_subdirectory(plugin.2/childplugin)
 add_subdirectory(plugin.2.1/childplugin)
 add_subdirectory(plugin.2.2)
 add_subdirectory(moduleWithQmlSingleton)
+add_subdirectory(optionalPlugin)
diff --git a/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/.prev_CMakeLists.txt b/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/.prev_CMakeLists.txt
new file mode 100644
index 0000000000..375ade482a
--- /dev/null
+++ b/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/.prev_CMakeLists.txt
@@ -0,0 +1,21 @@
+# Generated from optionalPlugin.pro.
+
+#####################################################################
+## optionalPlugin Generic Library:
+#####################################################################
+
+qt_add_cmake_library(optionalPlugin
+    MODULE
+    OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/../imports/QtQuick/Shapes"
+    SOURCES
+        optionalPlugin.cpp
+    PUBLIC_LIBRARIES
+        Qt::Core
+        Qt::Qml
+)
+
+#### Keys ignored in scope 1:.:.:optionalPlugin.pro:<TRUE>:
+# IMPORT_FILES = "qmldir"
+# TEMPLATE = "lib"
+
+qt_autogen_tools_initial_setup(optionalPlugin)
diff --git a/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/CMakeLists.txt b/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/CMakeLists.txt
new file mode 100644
index 0000000000..49b2bce8b7
--- /dev/null
+++ b/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/CMakeLists.txt
@@ -0,0 +1,26 @@
+# Generated from optionalPlugin.pro.
+
+#####################################################################
+## optionalPlugin Generic Library:
+#####################################################################
+
+qt_add_cmake_library(optionalPlugin
+    MODULE
+    OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/../imports/QtQuick/Shapes"
+    SOURCES
+        optionalPlugin.cpp
+    PUBLIC_LIBRARIES
+        Qt::Core
+        Qt::Qml
+)
+
+#### Keys ignored in scope 1:.:.:optionalPlugin.pro:<TRUE>:
+# IMPORT_FILES = "qmldir"
+# TEMPLATE = "lib"
+
+qt_autogen_tools_initial_setup(optionalPlugin)
+# special case begin
+file(COPY qmldir
+    DESTINATION "${CMAKE_CURRENT_BINARY_DIR}/../imports/QtQuick/Shapes"
+)
+# special case end
diff --git a/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/optionalPlugin.cpp b/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/optionalPlugin.cpp
new file mode 100644
index 0000000000..46855d76c9
--- /dev/null
+++ b/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/optionalPlugin.cpp
@@ -0,0 +1,46 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** 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 https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtQml/qqmlextensionplugin.h>
+#include <QtQml/qqml.h>
+#include <QDebug>
+
+class OptionalPlugin : public QQmlEngineExtensionPlugin
+{
+    Q_OBJECT
+    Q_PLUGIN_METADATA(IID QQmlEngineExtensionInterface_iid)
+
+public:
+    OptionalPlugin()
+    {
+        qFatal("optional plugin created");
+    }
+};
+
+#include "optionalPlugin.moc"
+
diff --git a/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/optionalPlugin.pro b/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/optionalPlugin.pro
new file mode 100644
index 0000000000..f1d64f969a
--- /dev/null
+++ b/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/optionalPlugin.pro
@@ -0,0 +1,10 @@
+TEMPLATE = lib
+CONFIG += plugin
+SOURCES = optionalPlugin.cpp
+QT = core qml
+DESTDIR = ../imports/QtQuick/Shapes
+
+IMPORT_FILES = \
+        qmldir
+
+include (../../../shared/imports.pri)
diff --git a/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/qmldir b/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/qmldir
new file mode 100644
index 0000000000..0d37717621
--- /dev/null
+++ b/tests/auto/qml/qqmlmoduleplugin/optionalPlugin/qmldir
@@ -0,0 +1,2 @@
+module QtQuick.Shapes
+optional plugin optionalPlugin
diff --git a/tests/auto/qml/qqmlmoduleplugin/qqmlmoduleplugin.pro b/tests/auto/qml/qqmlmoduleplugin/qqmlmoduleplugin.pro
index 44b3ab14e6..518e911179 100644
--- a/tests/auto/qml/qqmlmoduleplugin/qqmlmoduleplugin.pro
+++ b/tests/auto/qml/qqmlmoduleplugin/qqmlmoduleplugin.pro
@@ -1,4 +1,3 @@
-QT = core
 TEMPLATE = subdirs
 SUBDIRS =\
     plugin\
@@ -21,9 +20,8 @@ SUBDIRS =\
     plugin.2/childplugin\
     plugin.2.1/childplugin\
     plugin.2.2\
-    moduleWithQmlSingleton
+    moduleWithQmlSingleton\
+    optionalPlugin
 
 tst_qqmlmoduleplugin_pro.depends += plugin
 SUBDIRS += tst_qqmlmoduleplugin.pro
-
-QT += core-private gui-private qml-private
diff --git a/tests/auto/qml/qqmlmoduleplugin/tst_qqmlmoduleplugin.cpp b/tests/auto/qml/qqmlmoduleplugin/tst_qqmlmoduleplugin.cpp
index f15d53d022..3590eeb768 100644
--- a/tests/auto/qml/qqmlmoduleplugin/tst_qqmlmoduleplugin.cpp
+++ b/tests/auto/qml/qqmlmoduleplugin/tst_qqmlmoduleplugin.cpp
@@ -39,6 +39,8 @@
 #include <QCborValue>
 #endif
 
+#include <QtQuickShapes/private/qquickshapesglobal_p.h>
+
 #if defined(Q_OS_MAC)
 // For _PC_CASE_SENSITIVE
 #include <unistd.h>
@@ -83,6 +85,7 @@ private slots:
     void importsChildPlugin21();
     void parallelPluginImport();
     void multiSingleton();
+    void optionalPlugin();
 
 private:
     QString m_importsDirectory;
@@ -805,6 +808,20 @@ void tst_qqmlmoduleplugin::multiSingleton()
     delete object;
 }
 
+void tst_qqmlmoduleplugin::optionalPlugin()
+{
+    // Force QtQuickShapes to be linked.
+    volatile auto registration = &qml_register_types_QtQuick_Shapes;
+    Q_UNUSED(registration);
+
+    QQmlEngine engine;
+    engine.setImportPathList({m_importsDirectory});
+    QQmlComponent component(&engine);
+    component.setData("import QtQuick.Shapes\nShapePath {}\n", QUrl());
+    QScopedPointer<QObject> object10(component.create());
+    QVERIFY(!object10.isNull());
+}
+
 
 QTEST_MAIN(tst_qqmlmoduleplugin)
 
diff --git a/tests/auto/qml/qqmlmoduleplugin/tst_qqmlmoduleplugin.pro b/tests/auto/qml/qqmlmoduleplugin/tst_qqmlmoduleplugin.pro
index 118ca26ee9..38de349cf7 100644
--- a/tests/auto/qml/qqmlmoduleplugin/tst_qqmlmoduleplugin.pro
+++ b/tests/auto/qml/qqmlmoduleplugin/tst_qqmlmoduleplugin.pro
@@ -18,4 +18,4 @@ staticPlugin.files = moduleWithStaticPlugin
 staticPlugin.prefix = /qt-project.org/imports/
 RESOURCES += staticPlugin
 
-QT += core-private gui-private qml-private network testlib
+QT += core-private gui-private qml-private network testlib quickshapes-private