SPIGOT-893: Fix bridge method registering generic listeners twice

2 files changed, 54 insertions, 0 deletions

diff --git a/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java b/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java
index 687029fb..21187717 100644
--- a/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java
+++ b/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java
@@ -250,6 +250,11 @@ public final class JavaPluginLoader implements PluginLoader {
         for (final Method method : methods) {
             final EventHandler eh = method.getAnnotation(EventHandler.class);
             if (eh == null) continue;
+            // Do not register bridge or synthetic methods to avoid event duplication
+            // Fixes SPIGOT-893
+            if (method.isBridge() || method.isSynthetic()) {
+                continue;
+            }
             final Class<?> checkClass;
             if (method.getParameterTypes().length != 1 || !Event.class.isAssignableFrom(checkClass = method.getParameterTypes()[0])) {
                 plugin.getLogger().severe(plugin.getDescription().getFullName() + " attempted to register an invalid EventHandler method signature \"" + method.toGenericString() + "\" in " + listener.getClass());
diff --git a/src/test/java/org/bukkit/event/SyntheticEventTest.java b/src/test/java/org/bukkit/event/SyntheticEventTest.java
new file mode 100644
index 00000000..df6cf000
--- /dev/null
+++ b/src/test/java/org/bukkit/event/SyntheticEventTest.java
@@ -0,0 +1,49 @@
+package org.bukkit.event;
+
+import org.bukkit.TestServer;
+import org.bukkit.plugin.PluginLoader;
+import org.bukkit.plugin.SimplePluginManager;
+import org.bukkit.plugin.TestPlugin;
+import org.bukkit.plugin.java.JavaPluginLoader;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class SyntheticEventTest {
+    @SuppressWarnings("deprecation")
+    @Test
+    public void test() {
+        final JavaPluginLoader loader = new JavaPluginLoader(TestServer.getInstance());
+        TestPlugin plugin = new TestPlugin(getClass().getName()) {
+            @Override
+            public PluginLoader getPluginLoader() {
+                return loader;
+            }
+        };
+        SimplePluginManager pluginManager = new SimplePluginManager(TestServer.getInstance(), null);
+
+        TestEvent event = new TestEvent(false);
+        Impl impl = new Impl();
+
+        pluginManager.registerEvents(impl, plugin);
+        pluginManager.callEvent(event);
+
+        Assert.assertEquals(1, impl.callCount);
+    }
+
+    public static abstract class Base<E extends Event> implements Listener {
+        int callCount = 0;
+
+        public void accept(E evt) {
+            System.out.println("Invk " + evt);
+            callCount++;
+        }
+    }
+
+    public static class Impl extends Base<TestEvent> {
+        @Override
+        @EventHandler
+        public void accept(TestEvent evt) {
+            super.accept(evt);
+        }
+    }
+}