support @decorated bean injection in decorator

docs/src/main/asciidoc/cdi.adoc

@@ -455,10 +455,15 @@ public class LargeTxAccount implements Account { <3>
    Account delegate; <4>
 
    @Inject
-   LogService logService; <5>
+   @Decorated
+   Bean<?> delegateInfo; <5>
+
+
+   @Inject
+   LogService logService; <6>
 
    void withdraw(BigDecimal amount) {
-      delegate.withdraw(amount); <6>
+      delegate.withdraw(amount); <7>
       if (amount.compareTo(1000) > 0) {
          logService.logWithdrawal(delegate, amount);
       }
@@ -470,8 +475,9 @@ public class LargeTxAccount implements Account { <3>
 <2> `@Decorator` marks a decorator component.
 <3> The set of decorated types includes all bean types which are Java interfaces, except for `java.io.Serializable`.
 <4> Each decorator must declare exactly one _delegate injection point_. The decorator applies to beans that are assignable to this delegate injection point.
-<5> Decorators can inject other beans.
-<6> The decorator may invoke any method of the delegate object. And the container invokes either the next decorator in the chain or the business method of the intercepted instance.
+<5> It is possible to get contextual info about the decorated bean by using the @Decorated qualifier.
+<6> Decorators can inject other beans.
+<7> The decorator may invoke any method of the delegate object. And the container invokes either the next decorator in the chain or the business method of the intercepted instance.
 
 NOTE: Instances of decorators are dependent objects of the bean instance they intercept, i.e. a new decorator instance is created for each intercepted bean.
 

independent-projects/arc/processor/src/main/java/io/quarkus/arc/processor/BeanArchives.java

@@ -21,6 +21,7 @@
 import jakarta.enterprise.context.Initialized;
 import jakarta.enterprise.context.control.ActivateRequestContext;
 import jakarta.enterprise.inject.Any;
+import jakarta.enterprise.inject.Decorated;
 import jakarta.enterprise.inject.Default;
 import jakarta.enterprise.inject.Intercepted;
 import jakarta.enterprise.inject.Model;
@@ -82,6 +83,7 @@ private static IndexView buildAdditionalIndex() {
         index(indexer, BeforeDestroyed.class.getName());
         index(indexer, Destroyed.class.getName());
         index(indexer, Intercepted.class.getName());
+        index(indexer, Decorated.class.getName());
         index(indexer, Model.class.getName());
         index(indexer, Lock.class.getName());
         index(indexer, All.class.getName());

independent-projects/arc/processor/src/main/java/io/quarkus/arc/processor/BuiltinBean.java

@@ -23,6 +23,7 @@
 import io.quarkus.arc.InjectableBean;
 import io.quarkus.arc.impl.BeanManagerProvider;
 import io.quarkus.arc.impl.BeanMetadataProvider;
+import io.quarkus.arc.impl.DecoratedBeanMetadataProvider;
 import io.quarkus.arc.impl.EventProvider;
 import io.quarkus.arc.impl.InjectionPointProvider;
 import io.quarkus.arc.impl.InstanceProvider;
@@ -57,6 +58,11 @@ public enum BuiltinBean {
                     && ip.getRequiredQualifiers().size() == 1
                     && ip.getRequiredQualifiers().iterator().next().name().equals(DotNames.INTERCEPTED),
             BuiltinBean::validateInterceptedBean, DotNames.BEAN),
+    DECORATED_BEAN(BuiltinBean::generateDecoratedBeanBytecode,
+            (ip, names) -> cdiAndRawTypeMatches(ip, DotNames.BEAN, DotNames.INJECTABLE_BEAN) && !ip.hasDefaultedQualifier()
+                    && ip.getRequiredQualifiers().size() == 1
+                    && ip.getRequiredQualifiers().iterator().next().name().equals(DotNames.DECORATED),
+            BuiltinBean::validateDecoratedBean, DotNames.BEAN),
     BEAN_MANAGER(BuiltinBean::generateBeanManagerBytecode, DotNames.BEAN_MANAGER, DotNames.BEAN_CONTAINER),
     EVENT(BuiltinBean::generateEventBytecode, DotNames.EVENT),
     RESOURCE(BuiltinBean::generateResourceBytecode, (ip, names) -> ip.getKind() == InjectionPointKind.RESOURCE,
@@ -321,6 +327,19 @@ private static void generateInterceptedBeanBytecode(GeneratorContext ctx) {
                 interceptedBeanMetadataProviderSupplier);
     }
 
+    private static void generateDecoratedBeanBytecode(GeneratorContext ctx) {
+        ResultHandle decoratedBeanMetadataProvider = ctx.constructor
+                .newInstance(MethodDescriptor.ofConstructor(DecoratedBeanMetadataProvider.class));
+
+        ResultHandle decoratedBeanMetadataProviderSupplier = ctx.constructor.newInstance(
+                MethodDescriptors.FIXED_VALUE_SUPPLIER_CONSTRUCTOR, decoratedBeanMetadataProvider);
+        ctx.constructor.writeInstanceField(
+                FieldDescriptor.of(ctx.clazzCreator.getClassName(), ctx.providerName,
+                        Supplier.class.getName()),
+                ctx.constructor.getThis(),
+                decoratedBeanMetadataProviderSupplier);
+    }
+
     private static void generateBeanManagerBytecode(GeneratorContext ctx) {
         ResultHandle beanManagerProvider = ctx.constructor.newInstance(
                 MethodDescriptor.ofConstructor(BeanManagerProvider.class));
@@ -515,6 +534,13 @@ private static void validateInterceptedBean(ValidatorContext ctx) {
         }
     }
 
+    private static void validateDecoratedBean(ValidatorContext ctx) {
+        if (ctx.injectionTarget.kind() != InjectionTargetInfo.TargetKind.BEAN
+                || !ctx.injectionTarget.asBean().isDecorator()) {
+            ctx.errors.accept(new DefinitionException("Only decorators can access intercepted bean metadata"));
+        }
+    }
+
     private static void validateEventMetadata(ValidatorContext ctx) {
         if (ctx.injectionTarget.kind() != TargetKind.OBSERVER) {
             ctx.errors.accept(new DefinitionException(

independent-projects/arc/processor/src/main/java/io/quarkus/arc/processor/DotNames.java

@@ -25,6 +25,7 @@
 import jakarta.enterprise.event.TransactionPhase;
 import jakarta.enterprise.inject.Alternative;
 import jakarta.enterprise.inject.Any;
+import jakarta.enterprise.inject.Decorated;
 import jakarta.enterprise.inject.Default;
 import jakarta.enterprise.inject.Disposes;
 import jakarta.enterprise.inject.Instance;
@@ -133,6 +134,7 @@ public final class DotNames {
     public static final DotName INVOCATION_CONTEXT = create(InvocationContext.class);
     public static final DotName ARC_INVOCATION_CONTEXT = create(ArcInvocationContext.class);
     public static final DotName DECORATOR = create(Decorator.class);
+    public static final DotName DECORATED = create(Decorated.class);
     public static final DotName DELEGATE = create(Delegate.class);
     public static final DotName SERIALIZABLE = create(Serializable.class);
     public static final DotName UNREMOVABLE = create(Unremovable.class);

independent-projects/arc/processor/src/main/java/io/quarkus/arc/processor/Injection.java

@@ -82,6 +82,15 @@ private static void validateInjections(InjectionPointInfo injectionPointInfo, Be
                                 "but was detected in: " + injectionPointInfo.getTargetInfo());
             }
 
+            // If a Bean instance with qualifier @Decorated is injected into a bean instance other than an decorator
+            // instance, the container automatically detects the problem and treats it as a definition error.
+            if (injectionPointInfo.getType().name().equals(DotNames.BEAN)
+                    && injectionPointInfo.getRequiredQualifier(DotNames.DECORATED) != null) {
+                throw new DefinitionException(
+                        "Invalid injection of @Decorated Bean<T>, can only be injected into decorators " +
+                                "but was detected in: " + injectionPointInfo.getTargetInfo());
+            }
+
             // the injection point is a field, an initializer method parameter or a bean constructor, with qualifier
             // @Default, then the type parameter of the injected Bean, or Interceptor must be the same as the type
             // declaring the injection point

independent-projects/arc/runtime/src/main/java/io/quarkus/arc/impl/DecoratedBeanMetadataProvider.java

@@ -0,0 +1,28 @@
+package io.quarkus.arc.impl;
+
+import static io.quarkus.arc.impl.CreationalContextImpl.unwrap;
+
+import jakarta.enterprise.context.spi.Contextual;
+import jakarta.enterprise.context.spi.CreationalContext;
+import jakarta.enterprise.inject.Decorated;
+import jakarta.enterprise.inject.spi.Bean;
+
+import io.quarkus.arc.InjectableReferenceProvider;
+
+/**
+ * {@link Decorated} {@link Bean} metadata provider.
+ */
+public class DecoratedBeanMetadataProvider implements InjectableReferenceProvider<Contextual<?>> {
+
+    @Override
+    public Contextual<?> get(CreationalContext<Contextual<?>> creationalContext) {
+        // First attempt to obtain the creational context of the decorator bean and then the creational context of the decorated bean
+        CreationalContextImpl<?> parent = unwrap(creationalContext).getParent();
+        if (parent != null) {
+            parent = parent.getParent();
+            return parent != null ? parent.getContextual() : null;
+        }
+        return null;
+    }
+
+}

independent-projects/arc/tests/src/test/java/io/quarkus/arc/test/decorators/decorated/DecoratedTest.java

@@ -0,0 +1,75 @@
+package io.quarkus.arc.test.decorators.decorated;
+
+import java.util.Comparator;
+
+import jakarta.annotation.Priority;
+import jakarta.decorator.Decorator;
+import jakarta.decorator.Delegate;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.enterprise.context.Dependent;
+import jakarta.enterprise.inject.Any;
+import jakarta.enterprise.inject.Decorated;
+import jakarta.enterprise.inject.spi.Bean;
+import jakarta.inject.Inject;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.arc.Arc;
+import io.quarkus.arc.test.ArcTestContainer;
+import io.quarkus.arc.test.MyQualifier;
+
+public class DecoratedTest {
+
+    @RegisterExtension
+    public ArcTestContainer container = new ArcTestContainer(Converter.class, DecoratedBean.class,
+            TrimConverterDecorator.class, MyQualifier.class);
+
+    interface Converter<T> {
+
+        T convert(T value);
+
+    }
+
+    @Test
+    public void testDecoration() {
+        DecoratedBean bean = Arc.container().instance(DecoratedBean.class, new MyQualifier.Literal()).get();
+        Assertions.assertEquals(
+                DecoratedBean.class.getName() + " [@io.quarkus.arc.test.MyQualifier(), @jakarta.enterprise.inject.Any()]",
+                bean.convert("any value"));
+    }
+
+    @ApplicationScoped
+    @MyQualifier
+    static class DecoratedBean implements Converter<String> {
+
+        @Override
+        public String convert(String value) {
+            return "Replaced by the decorator";
+        }
+
+    }
+
+    @Dependent
+    @Priority(1)
+    @Decorator
+    static class TrimConverterDecorator implements Converter<String> {
+
+        @Inject
+        @Any
+        @Delegate
+        Converter<String> delegate;
+
+        @Inject
+        @Decorated
+        Bean<?> decorated;
+
+        @Override
+        public String convert(String value) {
+            return decorated.getBeanClass().getName() + " " + decorated.getQualifiers().stream()
+                    .sorted(Comparator.comparing(a -> a.annotationType().getName())).toList();
+        }
+
+    }
+}

independent-projects/arc/tests/src/test/java/io/quarkus/arc/test/decorators/decorated/InvalidDecoratedTest.java

@@ -0,0 +1,40 @@
+package io.quarkus.arc.test.decorators.decorated;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.enterprise.inject.Decorated;
+import jakarta.enterprise.inject.spi.Bean;
+import jakarta.inject.Inject;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.arc.test.ArcTestContainer;
+
+public class InvalidDecoratedTest {
+
+    @RegisterExtension
+    public ArcTestContainer container = ArcTestContainer.builder()
+            .beanClasses(InvalidBean.class)
+            .shouldFail()
+            .build();
+
+    @Test
+    public void testDecoration() {
+        assertNotNull(container.getFailure());
+        assertTrue(container.getFailure().getMessage().startsWith(
+                "Invalid injection of @Decorated Bean<T>, can only be injected into decorators but was detected in: "
+                        + InvalidBean.class.getName() + "#decorated"));
+    }
+
+    @ApplicationScoped
+    static class InvalidBean {
+
+        @Inject
+        @Decorated
+        Bean<?> decorated;
+
+    }
+}