Throw exception if required meta-annotation is not present

It is a configuration error if an alias is declared via @AliasFor for
an attribute in a meta-annotation and the meta-annotation is not
meta-present. However, prior to this commit, the support for validating
the configuration of @AliasFor in AnnotationUtils currently silently
ignored such errors.

This commit fixes this by throwing an AnnotationConfigurationException
whenever a required meta-annotation is not present or meta-present on
an annotation that declares an explicit alias for an attribute in the
meta-annotation.

Issue: SPR-13335

Author: sbrannen

spring-core/src/main/java/org/springframework/core/annotation/AliasFor.java

@@ -65,18 +65,18 @@
  * <li>Aliased attributes must declare the same return type.</li>
  * <li>Aliased attributes must declare a default value.</li>
  * <li>Aliased attributes must declare the same default value.</li>
- * <li>The {@link #annotation} attribute may remain set to the default,
- * although setting it to the declaring class for both attributes in the
- * pair is also valid.</li>
+ * <li>The {@link #annotation} attribute should remain set to the default.</li>
  * </ol>
  * </li>
  * <li><strong>Alias for attribute in meta-annotation</strong>:
  * <ol>
  * <li>The attribute that is an alias for an attribute in a meta-annotation
- * must be annotated with {@code @AliasFor}; the {@link #attribute} must
- * reference the aliased attribute in the meta-annotation; and the
- * {@link #annotation} must reference the meta-annotation.</li>
+ * must be annotated with {@code @AliasFor}, and the {@link #attribute} must
+ * reference the aliased attribute in the meta-annotation.</li>
  * <li>Aliased attributes must declare the same return type.</li>
+ * <li>The {@link #annotation} must reference the meta-annotation.</li>
+ * <li>The referenced meta-annotation must be <em>meta-present</em> on the
+ * annotation class that declares {@code @AliasFor}.</li>
  * </ol>
  * </li>
  * </ul>

spring-core/src/main/java/org/springframework/core/annotation/AnnotationUtils.java

@@ -1451,6 +1451,7 @@ static String getAliasedAttributeName(Method attribute, Class<? extends Annotati
 		Assert.isTrue(!Annotation.class.equals(targetAnnotationType),
 			"targetAnnotationType must not be java.lang.annotation.Annotation");
 
+		String attributeName = attribute.getName();
 		AliasFor aliasFor = attribute.getAnnotation(AliasFor.class);
 
 		// Nothing to check
@@ -1470,12 +1471,6 @@ static String getAliasedAttributeName(Method attribute, Class<? extends Annotati
 			return null;
 		}
 
-		// Wrong search scope?
-		if (searchWithinSameAnnotation && !sameTargetDeclared) {
-			return null;
-		}
-
-		String attributeName = attribute.getName();
 		String aliasedAttributeName = getAliasedAttributeName(aliasFor, attribute);
 
 		if (!StringUtils.hasText(aliasedAttributeName)) {
@@ -1485,10 +1480,25 @@ static String getAliasedAttributeName(Method attribute, Class<? extends Annotati
 			throw new AnnotationConfigurationException(msg);
 		}
 
-		if (sameTargetDeclared) {
+		if (!sameTargetDeclared) {
+			// Target annotation is not meta-present?
+			if (findAnnotation(sourceAnnotationType, aliasedAnnotationType) == null) {
+				String msg = String.format("@AliasFor declaration on attribute [%s] in annotation [%s] declares "
+						+ "an alias for attribute [%s] in meta-annotation [%s] which is not meta-present.",
+						attributeName, sourceAnnotationType.getName(), aliasedAttributeName,
+						aliasedAnnotationType.getName());
+				throw new AnnotationConfigurationException(msg);
+			}
+		}
+		else {
 			aliasedAnnotationType = sourceAnnotationType;
 		}
 
+		// Wrong search scope?
+		if (searchWithinSameAnnotation && !sameTargetDeclared) {
+			return null;
+		}
+
 		Method aliasedAttribute;
 		try {
 			aliasedAttribute = aliasedAnnotationType.getDeclaredMethod(aliasedAttributeName);

spring-core/src/test/java/org/springframework/core/annotation/AnnotationUtilsTests.java

@@ -831,6 +831,18 @@ public void synthesizeAnnotationWithAttributeAliasForAttributeWithDifferentDefau
 		synthesizeAnnotation(annotation);
 	}
 
+	@Test
+	public void synthesizeAnnotationWithAttributeAliasForMetaAnnotationThatIsNotMetaPresent() throws Exception {
+		AliasedComposedContextConfigNotMetaPresent annotation = AliasedComposedContextConfigNotMetaPresentClass.class.getAnnotation(AliasedComposedContextConfigNotMetaPresent.class);
+		exception.expect(AnnotationConfigurationException.class);
+		exception.expectMessage(startsWith("@AliasFor declaration on attribute [xmlConfigFile] in annotation"));
+		exception.expectMessage(containsString(AliasedComposedContextConfigNotMetaPresent.class.getName()));
+		exception.expectMessage(containsString("declares an alias for attribute [locations] in meta-annotation"));
+		exception.expectMessage(containsString(ContextConfig.class.getName()));
+		exception.expectMessage(endsWith("which is not meta-present."));
+		synthesizeAnnotation(annotation);
+	}
+
 	@Test
 	public void synthesizeAnnotationWithAttributeAliases() throws Exception {
 		Method method = WebController.class.getMethod("handleMappedWithValueAttribute");
@@ -1661,6 +1673,18 @@ static class AliasForWithMissingDefaultValuesClass {
 	static class AliasForAttributeWithDifferentDefaultValueClass {
 	}
 
+	// @ContextConfig --> Intentionally NOT meta-present
+	@Retention(RetentionPolicy.RUNTIME)
+	@interface AliasedComposedContextConfigNotMetaPresent {
+
+		@AliasFor(annotation = ContextConfig.class, attribute = "locations")
+		String xmlConfigFile();
+	}
+
+	@AliasedComposedContextConfigNotMetaPresent(xmlConfigFile = "test.xml")
+	static class AliasedComposedContextConfigNotMetaPresentClass {
+	}
+
 	@ContextConfig
 	@Retention(RetentionPolicy.RUNTIME)
 	@interface AliasedComposedContextConfig {