QPlugin: move some of the logic from moc's output to qplugin.h

This will allow us to make changes in QtCore itself, without having to
worry about moc compatibility.

The output uses an #ifdef so this version of moc can still be used to
compile earlier versions of Qt (usually, in cross-compilation
environments). See discussion in the mailing list[1].

[1] https://lists.qt-project.org/pipermail/development/2021-September/041732.html

Change-Id: I2de1b4dfacd443148279fffd16a39784c80c5f3b
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 61 insertions, 47 deletions

diff --git a/src/tools/moc/generator.cpp b/src/tools/moc/generator.cpp
index a21e44ba8f..3e838818f9 100644
--- a/src/tools/moc/generator.cpp
+++ b/src/tools/moc/generator.cpp
@@ -1573,62 +1573,76 @@ void Generator::generatePluginMetaData()
     if (cdef->pluginData.iid.isEmpty())
         return;
 
-    fprintf(out, "\nQT_PLUGIN_METADATA_SECTION\n"
-          "static constexpr unsigned char qt_pluginMetaData_%s[] = {\n"
-          "    'Q', 'T', 'M', 'E', 'T', 'A', 'D', 'A', 'T', 'A', ' ', '!',\n"
-          "    // metadata version, Qt version, architectural requirements\n"
-          "    0, QT_VERSION_MAJOR, QT_VERSION_MINOR, qPluginArchRequirements(),",
-          cdef->classname.constData());
-
-
-    CborDevice dev(out);
-    CborEncoder enc;
-    cbor_encoder_init_writer(&enc, CborDevice::callback, &dev);
-
-    CborEncoder map;
-    cbor_encoder_create_map(&enc, &map, CborIndefiniteLength);
-
-    dev.nextItem("\"IID\"");
-    cbor_encode_int(&map, int(QtPluginMetaDataKeys::IID));
-    cbor_encode_text_string(&map, cdef->pluginData.iid.constData(), cdef->pluginData.iid.size());
-
-    dev.nextItem("\"className\"");
-    cbor_encode_int(&map, int(QtPluginMetaDataKeys::ClassName));
-    cbor_encode_text_string(&map, cdef->classname.constData(), cdef->classname.size());
-
-    QJsonObject o = cdef->pluginData.metaData.object();
-    if (!o.isEmpty()) {
-        dev.nextItem("\"MetaData\"");
-        cbor_encode_int(&map, int(QtPluginMetaDataKeys::MetaData));
-        jsonObjectToCbor(&map, o);
-    }
+    auto outputCborData = [this]() {
+        CborDevice dev(out);
+        CborEncoder enc;
+        cbor_encoder_init_writer(&enc, CborDevice::callback, &dev);
+
+        CborEncoder map;
+        cbor_encoder_create_map(&enc, &map, CborIndefiniteLength);
+
+        dev.nextItem("\"IID\"");
+        cbor_encode_int(&map, int(QtPluginMetaDataKeys::IID));
+        cbor_encode_text_string(&map, cdef->pluginData.iid.constData(), cdef->pluginData.iid.size());
+
+        dev.nextItem("\"className\"");
+        cbor_encode_int(&map, int(QtPluginMetaDataKeys::ClassName));
+        cbor_encode_text_string(&map, cdef->classname.constData(), cdef->classname.size());
+
+        QJsonObject o = cdef->pluginData.metaData.object();
+        if (!o.isEmpty()) {
+            dev.nextItem("\"MetaData\"");
+            cbor_encode_int(&map, int(QtPluginMetaDataKeys::MetaData));
+            jsonObjectToCbor(&map, o);
+        }
 
-    if (!cdef->pluginData.uri.isEmpty()) {
-        dev.nextItem("\"URI\"");
-        cbor_encode_int(&map, int(QtPluginMetaDataKeys::URI));
-        cbor_encode_text_string(&map, cdef->pluginData.uri.constData(), cdef->pluginData.uri.size());
-    }
+        if (!cdef->pluginData.uri.isEmpty()) {
+            dev.nextItem("\"URI\"");
+            cbor_encode_int(&map, int(QtPluginMetaDataKeys::URI));
+            cbor_encode_text_string(&map, cdef->pluginData.uri.constData(), cdef->pluginData.uri.size());
+        }
 
-    // Add -M args from the command line:
-    for (auto it = cdef->pluginData.metaArgs.cbegin(), end = cdef->pluginData.metaArgs.cend(); it != end; ++it) {
-        const QJsonArray &a = it.value();
-        QByteArray key = it.key().toUtf8();
-        dev.nextItem(QByteArray("command-line \"" + key + "\"").constData());
-        cbor_encode_text_string(&map, key.constData(), key.size());
-        jsonArrayToCbor(&map, a);
-    }
+        // Add -M args from the command line:
+        for (auto it = cdef->pluginData.metaArgs.cbegin(), end = cdef->pluginData.metaArgs.cend(); it != end; ++it) {
+            const QJsonArray &a = it.value();
+            QByteArray key = it.key().toUtf8();
+            dev.nextItem(QByteArray("command-line \"" + key + "\"").constData());
+            cbor_encode_text_string(&map, key.constData(), key.size());
+            jsonArrayToCbor(&map, a);
+        }
 
-    // Close the CBOR map manually
-    dev.nextItem();
-    cbor_encoder_close_container(&enc, &map);
-    fputs("\n};\n", out);
+        // Close the CBOR map manually
+        dev.nextItem();
+        cbor_encoder_close_container(&enc, &map);
+    };
 
     // 'Use' all namespaces.
     int pos = cdef->qualified.indexOf("::");
     for ( ; pos != -1 ; pos = cdef->qualified.indexOf("::", pos + 2) )
         fprintf(out, "using namespace %s;\n", cdef->qualified.left(pos).constData());
-    fprintf(out, "QT_MOC_EXPORT_PLUGIN(%s, %s)\n\n",
+
+    fputs("\n#ifdef QT_MOC_EXPORT_PLUGIN_V2", out);
+
+    // Qt 6.3+ output
+    fprintf(out, "\nstatic constexpr unsigned char qt_pluginMetaDataV2_%s[] = {",
+          cdef->classname.constData());
+    outputCborData();
+    fprintf(out, "\n};\nQT_MOC_EXPORT_PLUGIN_V2(%s, %s, qt_pluginMetaDataV2_%s)\n",
+            cdef->qualified.constData(), cdef->classname.constData(), cdef->classname.constData());
+
+    // compatibility with Qt 6.0-6.2
+    fprintf(out, "#else\nQT_PLUGIN_METADATA_SECTION\n"
+          "static constexpr unsigned char qt_pluginMetaData_%s[] = {\n"
+          "    'Q', 'T', 'M', 'E', 'T', 'A', 'D', 'A', 'T', 'A', ' ', '!',\n"
+          "    // metadata version, Qt version, architectural requirements\n"
+          "    0, QT_VERSION_MAJOR, QT_VERSION_MINOR, qPluginArchRequirements(),",
+          cdef->classname.constData());
+    outputCborData();
+    fprintf(out, "\n};\nQT_MOC_EXPORT_PLUGIN(%s, %s)\n"
+                 "#endif  // QT_MOC_EXPORT_PLUGIN_V2\n",
             cdef->qualified.constData(), cdef->classname.constData());
+
+    fputs("\n", out);
 }
 
 QT_WARNING_DISABLE_GCC("-Wunused-function")