moc: add -M<key=value> to ease static qml plugin linking

A module plugin in qml belongs to a URI/namespace. This
uri is resolved run-time by QtDeclarative by knowing the
path of the qmldir that references the plugin.
For static plugins this becomes a problem, since we lost
the information regarding which plugin belongs to which
qmldir, since a static plugin has no file path.

To avoid pushing the responsibility of clarifying this
onto the application developer, it is better to embed this
information into the meta data of the plugins themselves.
Since this information can be resolved by the
build system, a new option to moc has been added:
-M<key=value>
that will let you add meta tags to the meta data from
the command line to each class that has an IID specified.
For the URI case, we can then e.g do:
-Muri=QtQuick.Controls -Muri=QtQuick.Controls.Private

Change-Id: I81a156660148fc94db6f3cac0473e9e1c8458c58
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

src/tools/moc/generator.cpp

@@ -1462,6 +1462,10 @@ void Generator::generatePluginMetaData()
     data.insert(debugKey, QJsonValue(false));
     data.insert(QStringLiteral("MetaData"), cdef->pluginData.metaData.object());
 
+    // Add -M args from the command line:
+    foreach (const QString &key, cdef->pluginData.metaArgs.keys())
+        data.insert(key, cdef->pluginData.metaArgs.value(key));
+
     fputs("\nQT_PLUGIN_METADATA_SECTION const uint qt_section_alignment_dummy = 42;\n\n"
           "#ifdef QT_NO_DEBUG\n", out);
     writePluginMetaData(out, data);

src/tools/moc/main.cpp

@@ -242,6 +242,11 @@ int runMoc(int argc, char **argv)
     undefineOption.setValueName(QStringLiteral("macro"));
     parser.addOption(undefineOption);
 
+    QCommandLineOption metadataOption(QStringLiteral("M"));
+    metadataOption.setDescription(QStringLiteral("Add key/value pair to plugin meta data"));
+    metadataOption.setValueName(QStringLiteral("key=value"));
+    parser.addOption(metadataOption);
+
     QCommandLineOption noIncludeOption(QStringLiteral("i"));
     noIncludeOption.setDescription(QStringLiteral("Do not generate an #include statement."));
     parser.addOption(noIncludeOption);
@@ -385,6 +390,24 @@ int runMoc(int argc, char **argv)
         moc.filename = filename.toLocal8Bit();
     }
 
+    foreach (const QString &md, parser.values(metadataOption)) {
+        int split = md.indexOf(QLatin1Char('='));
+        QString key = md.left(split);
+        QString value = md.mid(split + 1);
+
+        if (split == -1 || key.isEmpty() || value.isEmpty()) {
+            error("missing key or value for option '-M'");
+        } else if (key.indexOf(QLatin1Char('.')) != -1) {
+            // Don't allow keys with '.' for now, since we might need this
+            // format later for more advanced meta data API
+            error("A key cannot contain the letter '.' for option '-M'");
+        } else {
+            QJsonArray array = moc.metaArgs.value(key);
+            array.append(value);
+            moc.metaArgs.insert(key, array);
+        }
+    }
+
     moc.currentFilenames.push(filename.toLocal8Bit());
     moc.includes = pp.includes;
 

src/tools/moc/moc.cpp

@@ -787,6 +787,10 @@ void Moc::parse()
             if (!def.hasQObject && !def.hasQGadget)
                 error("Class declarations lacks Q_OBJECT macro.");
 
+            // Add meta tags to the plugin meta data:
+            if (!def.pluginData.iid.isEmpty())
+                def.pluginData.metaArgs = metaArgs;
+
             checkSuperClasses(&def);
             checkProperties(&def);
 

src/tools/moc/moc.h

@@ -47,6 +47,8 @@
 #include <qmap.h>
 #include <qpair.h>
 #include <qjsondocument.h>
+#include <qjsonarray.h>
+#include <qjsonobject.h>
 #include <stdio.h>
 #include <ctype.h>
 
@@ -171,6 +173,7 @@ struct ClassDef {
 
     struct PluginData {
         QByteArray iid;
+        QMap<QString, QJsonArray> metaArgs;
         QJsonDocument metaData;
     } pluginData;
 
@@ -213,6 +216,7 @@ public:
     QMap<QByteArray, QByteArray> interface2IdMap;
     QList<QByteArray> metaTypes;
     QSet<QByteArray> knownQObjectClasses;
+    QMap<QString, QJsonArray> metaArgs;
 
     void parse();
     void generate(FILE *out);

tests/auto/tools/moc/moc.pro

@@ -22,7 +22,8 @@ HEADERS += using-namespaces.h no-keywords.h task87883.h c-comments.h backslash-n
            cxx11-explicit-override-control.h \
            forward-declared-param.h \
            parse-defines.h \
-           function-with-attributes.h
+           function-with-attributes.h \
+           plugin_metadata.h
 
 
 if(*-g++*|*-icc*|*-clang*|*-llvm):!irix-*:!win32-*: HEADERS += os9-newlines.h win-newlines.h
@@ -35,3 +36,8 @@ qtHaveModule(dbus) {
     QT += dbus
 }
 DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0
+
+# tst_Moc::specifyMetaTagsFromCmdline()
+# Ensure that plugin_metadata.h are moc-ed with some extra -M arguments:
+QMAKE_MOC_OPTIONS += -Muri=com.company.app -Muri=com.company.app.private
+

tests/auto/tools/moc/plugin_metadata.h

@@ -0,0 +1,53 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef TESTPLUGINMETADATA
+#define TESTPLUGINMETADATA
+
+#include <QtPlugin>
+
+class TestPluginMetaData : public QObject
+{
+    Q_OBJECT
+    Q_PLUGIN_METADATA(IID "test.meta.tags")
+};
+
+#endif

tests/auto/tools/moc/tst_moc.cpp

@@ -531,6 +531,7 @@ private slots:
     void frameworkSearchPath();
     void cstyleEnums();
     void defineMacroViaCmdline();
+    void specifyMetaTagsFromCmdline();
     void invokable();
     void singleFunctionKeywordSignalAndSlot();
     void templateGtGt();
@@ -1170,6 +1171,37 @@ void tst_Moc::defineMacroViaCmdline()
 #endif
 }
 
+// tst_Moc::specifyMetaTagsFromCmdline()
+// plugin_metadata.h contains a plugin which we register here. Since we're not building this
+// application as a plugin, we need top copy some of the initializer code found in qplugin.h:
+extern "C" QObject *qt_plugin_instance();
+extern "C" const char *qt_plugin_query_metadata();
+class StaticPluginInstance{
+public:
+    StaticPluginInstance() {
+        QStaticPlugin plugin = { &qt_plugin_instance, &qt_plugin_query_metadata };
+        qRegisterStaticPluginFunction(plugin);
+    }
+};
+static StaticPluginInstance staticInstance;
+
+void tst_Moc::specifyMetaTagsFromCmdline() {
+    foreach (const QStaticPlugin &plugin, QPluginLoader::staticPlugins()) {
+        const QString iid = plugin.metaData().value(QLatin1String("IID")).toString();
+        if (iid == QLatin1String("test.meta.tags")) {
+            const QJsonArray metaTagsUriList = plugin.metaData().value("uri").toArray();
+            QCOMPARE(metaTagsUriList.size(), 2);
+
+            // The following uri-s are set in the pro file using
+            // -Muri=com.company.app -Muri=com.company.app.private
+            QCOMPARE(metaTagsUriList[0].toString(), QLatin1String("com.company.app"));
+            QCOMPARE(metaTagsUriList[1].toString(), QLatin1String("com.company.app.private"));
+            return;
+        }
+    }
+    QFAIL("Could not find plugin with IID 'test.meta.tags'");
+}
+
 void tst_Moc::invokable()
 {
     {