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>

1 files changed, 19 insertions, 2 deletions

diff --git a/src/qml/qmldirparser/qqmldirparser.cpp b/src/qml/qmldirparser/qqmldirparser.cpp
index cb16d2e57a..a8a450d2ca 100644
--- a/src/qml/qmldirparser/qqmldirparser.cpp
+++ b/src/qml/qmldirparser/qqmldirparser.cpp
@@ -178,15 +178,32 @@ bool QQmlDirParser::parse(const QString &source)
         } else if (sections[0] == QLatin1String("plugin")) {
             if (sectionCount < 2 || sectionCount > 3) {
                 reportError(lineNumber, 0,
-                            QStringLiteral("plugin directive requires one or two arguments, but %1 were provided").arg(sectionCount - 1));
+                            QStringLiteral("plugin directive requires one or two arguments, but %1 were provided")
+                            .arg(sectionCount - 1));
 
                 continue;
             }
 
-            const Plugin entry(sections[1], sections[2]);
+            const Plugin entry(sections[1], sections[2], false);
 
             _plugins.append(entry);
 
+        } else if (sections[0] == QLatin1String("optional")) {
+            if (sectionCount < 2 || sections[1] != QLatin1String("plugin")) {
+                reportError(lineNumber, 0, QStringLiteral("only plugins can be optional"));
+                continue;
+            }
+
+            if (sectionCount < 3 || sectionCount > 4) {
+                reportError(lineNumber, 0,
+                            QStringLiteral("plugin directive requires one or two arguments, but %1 were provided")
+                            .arg(sectionCount - 2));
+                continue;
+            }
+
+            const Plugin entry(sections[2], sections[3], true);
+            _plugins.append(entry);
+
         } else if (sections[0] == QLatin1String("classname")) {
             if (sectionCount < 2) {
                 reportError(lineNumber, 0,