Allow contravariant wildcards in Event and covariant wildcards in Instance

Author: manovotn

impl/src/main/java/org/jboss/weld/bean/builtin/AbstractFacade.java

@@ -20,6 +20,7 @@
 import java.lang.annotation.Annotation;
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
+import java.lang.reflect.WildcardType;
 import java.util.Set;
 
 import jakarta.enterprise.context.spi.CreationalContext;
@@ -40,12 +41,23 @@ public abstract class AbstractFacade<T, X> {
     protected static Type getFacadeType(InjectionPoint injectionPoint) {
         Type genericType = injectionPoint.getType();
         if (genericType instanceof ParameterizedType) {
-            return ((ParameterizedType) genericType).getActualTypeArguments()[0];
+            Type typeArgument = ((ParameterizedType) genericType).getActualTypeArguments()[0];
+            if (typeArgument instanceof WildcardType) {
+                return getWildcardBound((WildcardType) typeArgument);
+            }
+            return typeArgument;
         } else {
             throw new IllegalStateException(BeanLogger.LOG.typeParameterMustBeConcrete(injectionPoint));
         }
     }
 
+    private static Type getWildcardBound(WildcardType wildcard) {
+        if (wildcard.getLowerBounds().length > 0) {
+            return wildcard.getLowerBounds()[0];
+        }
+        return wildcard.getUpperBounds()[0];
+    }
+
     private final BeanManagerImpl beanManager;
     private final InjectionPoint injectionPoint;
     // The CreationalContext used to create the facade which was injected.

impl/src/main/java/org/jboss/weld/bootstrap/Validator.java

@@ -864,13 +864,46 @@ private static void checkFacadeInjectionPoint(InjectionPoint injectionPoint, Cla
                             Formats.formatAsStackTraceElement(injectionPoint));
                 }
                 if (parameterizedType.getActualTypeArguments()[0] instanceof WildcardType) {
-                    throw ValidatorLogger.LOG.injectionPointHasWildcard(injectionPoint,
-                            Formats.formatAsStackTraceElement(injectionPoint));
+                    WildcardType wildcard = (WildcardType) parameterizedType.getActualTypeArguments()[0];
+                    if (!isAllowedWildcard(wildcard, type)) {
+                        throw ValidatorLogger.LOG.injectionPointHasWildcard(injectionPoint,
+                                Formats.formatAsStackTraceElement(injectionPoint));
+                    }
+                }
+            } else if (type.equals(Event.class) && parameterizedType.getRawType().equals(Instance.class)) {
+                // check for wildcard in Event injected via Instance -> @Inject Instance<Event<?>>
+                Type instanceTypeArgument = parameterizedType.getActualTypeArguments()[0];
+                if (instanceTypeArgument instanceof ParameterizedType
+                        && ((ParameterizedType) instanceTypeArgument).getRawType().equals(Event.class)
+                        && ((ParameterizedType) instanceTypeArgument).getActualTypeArguments()[0] instanceof WildcardType) {
+                    WildcardType nestedWildcard = (WildcardType) ((ParameterizedType) instanceTypeArgument)
+                            .getActualTypeArguments()[0];
+                    if (!isAllowedWildcard(nestedWildcard, Event.class)) {
+                        throw ValidatorLogger.LOG.injectionPointHasWildcard(injectionPoint,
+                                Formats.formatAsStackTraceElement(injectionPoint));
+                    }
                 }
             }
         }
     }
 
+    /**
+     * Event is contravariant so {@code Event<? super X>} is allowed.
+     * Instance is covariant so {@code Instance<? extends X>} is allowed.
+     * Unbounded wildcards are rejected for both.
+     */
+    private static boolean isAllowedWildcard(WildcardType wildcard, Class<?> facadeType) {
+        if (facadeType.equals(Event.class)) {
+            return wildcard.getLowerBounds().length > 0;
+        }
+        if (facadeType.equals(Instance.class)) {
+            Type[] upperBounds = wildcard.getUpperBounds();
+            return wildcard.getLowerBounds().length == 0
+                    && upperBounds.length > 0 && !Object.class.equals(upperBounds[0]);
+        }
+        return false;
+    }
+
     public static void checkBeanMetadataInjectionPoint(Object bean, InjectionPoint ip, Type expectedTypeArgument) {
         if (!(ip.getType() instanceof ParameterizedType)) {
             throw ValidatorLogger.LOG.invalidBeanMetadataInjectionPointType(ip.getType(), ip,

tests-arquillian/src/test/java/org/jboss/weld/tests/event/wildcard/contravariant/BeanWithContravariantEvent.java

@@ -0,0 +1,16 @@
+package org.jboss.weld.tests.event.wildcard.contravariant;
+
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.enterprise.event.Event;
+import jakarta.inject.Inject;
+
+@ApplicationScoped
+public class BeanWithContravariantEvent {
+
+    @Inject
+    Event<? super LifecycleEvent<?>> lifecycleEvents;
+
+    public void fireEvent(LifecycleEvent<?> event) {
+        lifecycleEvents.fire(event);
+    }
+}

tests-arquillian/src/test/java/org/jboss/weld/tests/event/wildcard/contravariant/BeanWithSimpleContravariantEvent.java

@@ -0,0 +1,16 @@
+package org.jboss.weld.tests.event.wildcard.contravariant;
+
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.enterprise.event.Event;
+import jakarta.inject.Inject;
+
+@ApplicationScoped
+public class BeanWithSimpleContravariantEvent {
+
+    @Inject
+    Event<? super Widget> widgetEvents;
+
+    public void fireWidget(Widget widget) {
+        widgetEvents.fire(widget);
+    }
+}

tests-arquillian/src/test/java/org/jboss/weld/tests/event/wildcard/contravariant/EventContravariantWildcardTest.java

@@ -0,0 +1,47 @@
+package org.jboss.weld.tests.event.wildcard.contravariant;
+
+import static org.junit.Assert.assertTrue;
+
+import org.jboss.arquillian.container.test.api.Deployment;
+import org.jboss.arquillian.junit.Arquillian;
+import org.jboss.shrinkwrap.api.Archive;
+import org.jboss.shrinkwrap.api.BeanArchive;
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.weld.test.util.Utils;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/**
+ * Verifies that {@code Event<? super X>} injection points are valid and functional.
+ * {@code Event} is naturally contravariant — you fire subtypes into it — so a
+ * lower-bounded wildcard is a legitimate use case.
+ * <p>
+ * This reproduces the scenario reported by Gavin King where Jakarta Data injects
+ * {@code Event<? super LifecycleEvent<?>>}.
+ *
+ * @see <a href="https://github.com/jakartaee/cdi/issues/888">CDI #888</a>
+ */
+@RunWith(Arquillian.class)
+public class EventContravariantWildcardTest {
+
+    @Deployment
+    public static Archive<?> getDeployment() {
+        return ShrinkWrap.create(BeanArchive.class, Utils.getDeploymentNameAsHash(EventContravariantWildcardTest.class))
+                .addClasses(BeanWithContravariantEvent.class, LifecycleEvent.class, LifecycleEventObserver.class,
+                        BeanWithSimpleContravariantEvent.class, Widget.class, WidgetObserver.class);
+    }
+
+    @Test
+    public void testParameterizedContravariantEventWildcard(BeanWithContravariantEvent bean,
+            LifecycleEventObserver observer) {
+        bean.fireEvent(new LifecycleEvent<>("test"));
+        assertTrue("LifecycleEvent should have been observed", observer.isObserved());
+    }
+
+    @Test
+    public void testSimpleContravariantEventWildcard(BeanWithSimpleContravariantEvent bean,
+            WidgetObserver observer) {
+        bean.fireWidget(new Widget("test"));
+        assertTrue("Widget event should have been observed", observer.isObserved());
+    }
+}

tests-arquillian/src/test/java/org/jboss/weld/tests/event/wildcard/contravariant/LifecycleEvent.java

@@ -0,0 +1,14 @@
+package org.jboss.weld.tests.event.wildcard.contravariant;
+
+public class LifecycleEvent<T> {
+
+    private final T payload;
+
+    public LifecycleEvent(T payload) {
+        this.payload = payload;
+    }
+
+    public T getPayload() {
+        return payload;
+    }
+}

tests-arquillian/src/test/java/org/jboss/weld/tests/event/wildcard/contravariant/LifecycleEventObserver.java

@@ -0,0 +1,18 @@
+package org.jboss.weld.tests.event.wildcard.contravariant;
+
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.enterprise.event.Observes;
+
+@ApplicationScoped
+public class LifecycleEventObserver {
+
+    private boolean observed = false;
+
+    public void onLifecycleEvent(@Observes LifecycleEvent<?> event) {
+        observed = true;
+    }
+
+    public boolean isObserved() {
+        return observed;
+    }
+}

tests-arquillian/src/test/java/org/jboss/weld/tests/event/wildcard/contravariant/Widget.java

@@ -0,0 +1,14 @@
+package org.jboss.weld.tests.event.wildcard.contravariant;
+
+public class Widget {
+
+    private final String name;
+
+    public Widget(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+}

tests-arquillian/src/test/java/org/jboss/weld/tests/event/wildcard/contravariant/WidgetObserver.java

@@ -0,0 +1,18 @@
+package org.jboss.weld.tests.event.wildcard.contravariant;
+
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.enterprise.event.Observes;
+
+@ApplicationScoped
+public class WidgetObserver {
+
+    private boolean observed = false;
+
+    public void onWidget(@Observes Widget event) {
+        observed = true;
+    }
+
+    public boolean isObserved() {
+        return observed;
+    }
+}

tests-arquillian/src/test/java/org/jboss/weld/tests/event/wildcard/covariant/BeanWithCovariantEvent.java

@@ -0,0 +1,12 @@
+package org.jboss.weld.tests.event.wildcard.covariant;
+
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.enterprise.event.Event;
+import jakarta.inject.Inject;
+
+@ApplicationScoped
+public class BeanWithCovariantEvent {
+
+    @Inject
+    Event<? extends Widget> covariantEvent;
+}