From 3020413e971867be7e8d036c4a025342b6d10dab Mon Sep 17 00:00:00 2001
From: Matej Novotny <manovotn@redhat.com>
Date: Wed, 2 Mar 2022 10:43:46 +0100
Subject: [PATCH] Arc - mention that decorating built-in types is not
 supported; log a warning if we detect such case.

---
 docs/src/main/asciidoc/cdi-reference.adoc     |  1 +
 .../io/quarkus/arc/processor/Decorators.java  | 10 +++
 .../DecoratorForBuiltInEventTypeTest.java     | 72 +++++++++++++++++++
 3 files changed, 83 insertions(+)
 create mode 100644 independent-projects/arc/tests/src/test/java/io/quarkus/arc/test/decorators/validation/DecoratorForBuiltInEventTypeTest.java

diff --git a/docs/src/main/asciidoc/cdi-reference.adoc b/docs/src/main/asciidoc/cdi-reference.adoc
index 702d861df6ace..fb57163d3a5e1 100644
--- a/docs/src/main/asciidoc/cdi-reference.adoc
+++ b/docs/src/main/asciidoc/cdi-reference.adoc
@@ -214,6 +214,7 @@ public class CounterBean {
 * Passivation and passivating scopes are not supported
 * Interceptor methods on superclasses are not implemented yet
 * `@Interceptors` is not supported
+* Decoration of built-in beans, such as `Event`, is not supported
 
 [[nonstandard_features]]
 == Non-standard Features
diff --git a/independent-projects/arc/processor/src/main/java/io/quarkus/arc/processor/Decorators.java b/independent-projects/arc/processor/src/main/java/io/quarkus/arc/processor/Decorators.java
index 46810ff215bca..92370dae42b4a 100644
--- a/independent-projects/arc/processor/src/main/java/io/quarkus/arc/processor/Decorators.java
+++ b/independent-projects/arc/processor/src/main/java/io/quarkus/arc/processor/Decorators.java
@@ -80,6 +80,16 @@ static DecoratorInfo createDecorator(ClassInfo decoratorClass, BeanDeployment be
                 throw new DefinitionException("The delegate type " + delegateInjectionPoint.getRequiredType()
                         + " does not implement the decorated type: " + decoratedType);
             }
+            for (BuiltinBean bean : BuiltinBean.values()) {
+                if (bean.equals(BuiltinBean.RESOURCE)) {
+                    // do not take Resource into consideration
+                    continue;
+                }
+                if (bean.hasRawTypeDotName(decoratedType.name())) {
+                    throw new UnsupportedOperationException("Decorating built-in bean types is not supported! " +
+                            "Decorator " + decoratorClass + " is attempting to decorate " + decoratedType.name());
+                }
+            }
         }
 
         if (priority == null) {
diff --git a/independent-projects/arc/tests/src/test/java/io/quarkus/arc/test/decorators/validation/DecoratorForBuiltInEventTypeTest.java b/independent-projects/arc/tests/src/test/java/io/quarkus/arc/test/decorators/validation/DecoratorForBuiltInEventTypeTest.java
new file mode 100644
index 0000000000000..1658e8f866329
--- /dev/null
+++ b/independent-projects/arc/tests/src/test/java/io/quarkus/arc/test/decorators/validation/DecoratorForBuiltInEventTypeTest.java
@@ -0,0 +1,72 @@
+package io.quarkus.arc.test.decorators.validation;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import io.quarkus.arc.Priority;
+import io.quarkus.arc.test.ArcTestContainer;
+import java.lang.annotation.Annotation;
+import java.util.concurrent.CompletionStage;
+import javax.decorator.Decorator;
+import javax.decorator.Delegate;
+import javax.enterprise.event.Event;
+import javax.enterprise.event.NotificationOptions;
+import javax.enterprise.util.TypeLiteral;
+import javax.inject.Inject;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+public class DecoratorForBuiltInEventTypeTest {
+
+    @RegisterExtension
+    public ArcTestContainer container = ArcTestContainer.builder()
+            .beanClasses(BadDecorator.class)
+            .shouldFail().build();
+
+    @Test
+    public void testFailure() {
+        assertNotNull(container.getFailure());
+        assertTrue(
+                container.getFailure().getMessage().contains("Decorating built-in bean types is not supported!"),
+                container.getFailure().getMessage());
+    }
+
+    @Decorator
+    @Priority(1)
+    static class BadDecorator<T> implements Event<T> {
+
+        @Delegate
+        @Inject
+        Event<T> delegate;
+
+        @Override
+        public void fire(T event) {
+
+        }
+
+        @Override
+        public Event<T> select(Annotation... qualifiers) {
+            return null;
+        }
+
+        @Override
+        public <U extends T> Event<U> select(Class<U> subtype, Annotation... qualifiers) {
+            return null;
+        }
+
+        @Override
+        public <U extends T> Event<U> select(TypeLiteral<U> subtype, Annotation... qualifiers) {
+            return null;
+        }
+
+        @Override
+        public <U extends T> CompletionStage<U> fireAsync(U event, NotificationOptions options) {
+            return null;
+        }
+
+        @Override
+        public <U extends T> CompletionStage<U> fireAsync(U event) {
+            return null;
+        }
+    }
+}