Merge branch '2.1.x'

Closes gh-18889

Author: wilkinsona

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/ConfigurationMetadataAnnotationProcessor.java

@@ -25,6 +25,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.Stack;
 
 import javax.annotation.processing.AbstractProcessor;
 import javax.annotation.processing.ProcessingEnvironment;
@@ -180,10 +181,10 @@ private void processElement(Element element) {
 			if (annotation != null) {
 				String prefix = getPrefix(annotation);
 				if (element instanceof TypeElement) {
-					processAnnotatedTypeElement(prefix, (TypeElement) element);
+					processAnnotatedTypeElement(prefix, (TypeElement) element, new Stack<TypeElement>());
 				}
 				else if (element instanceof ExecutableElement) {
-					processExecutableElement(prefix, (ExecutableElement) element);
+					processExecutableElement(prefix, (ExecutableElement) element, new Stack<TypeElement>());
 				}
 			}
 		}
@@ -192,13 +193,13 @@ else if (element instanceof ExecutableElement) {
 		}
 	}
 
-	private void processAnnotatedTypeElement(String prefix, TypeElement element) {
+	private void processAnnotatedTypeElement(String prefix, TypeElement element, Stack<TypeElement> seen) {
 		String type = this.metadataEnv.getTypeUtils().getQualifiedName(element);
 		this.metadataCollector.add(ItemMetadata.newGroup(prefix, type, type, null));
-		processTypeElement(prefix, element, null);
+		processTypeElement(prefix, element, null, seen);
 	}
 
-	private void processExecutableElement(String prefix, ExecutableElement element) {
+	private void processExecutableElement(String prefix, ExecutableElement element, Stack<TypeElement> seen) {
 		if ((!element.getModifiers().contains(Modifier.PRIVATE))
 				&& (TypeKind.VOID != element.getReturnType().getKind())) {
 			Element returns = this.processingEnv.getTypeUtils().asElement(element.getReturnType());
@@ -213,22 +214,27 @@ private void processExecutableElement(String prefix, ExecutableElement element)
 				}
 				else {
 					this.metadataCollector.add(group);
-					processTypeElement(prefix, (TypeElement) returns, element);
+					processTypeElement(prefix, (TypeElement) returns, element, seen);
 				}
 			}
 		}
 	}
 
-	private void processTypeElement(String prefix, TypeElement element, ExecutableElement source) {
-		new PropertyDescriptorResolver(this.metadataEnv).resolve(element, source).forEach((descriptor) -> {
-			this.metadataCollector.add(descriptor.resolveItemMetadata(prefix, this.metadataEnv));
-			if (descriptor.isNested(this.metadataEnv)) {
-				TypeElement nestedTypeElement = (TypeElement) this.metadataEnv.getTypeUtils()
-						.asElement(descriptor.getType());
-				String nestedPrefix = ConfigurationMetadata.nestedPrefix(prefix, descriptor.getName());
-				processTypeElement(nestedPrefix, nestedTypeElement, source);
-			}
-		});
+	private void processTypeElement(String prefix, TypeElement element, ExecutableElement source,
+			Stack<TypeElement> seen) {
+		if (!seen.contains(element)) {
+			seen.push(element);
+			new PropertyDescriptorResolver(this.metadataEnv).resolve(element, source).forEach((descriptor) -> {
+				this.metadataCollector.add(descriptor.resolveItemMetadata(prefix, this.metadataEnv));
+				if (descriptor.isNested(this.metadataEnv)) {
+					TypeElement nestedTypeElement = (TypeElement) this.metadataEnv.getTypeUtils()
+							.asElement(descriptor.getType());
+					String nestedPrefix = ConfigurationMetadata.nestedPrefix(prefix, descriptor.getName());
+					processTypeElement(nestedPrefix, nestedTypeElement, source, seen);
+				}
+			});
+			seen.pop();
+		}
 	}
 
 	private void processEndpoint(Element element, List<Element> annotations) {

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/ConfigurationMetadataAnnotationProcessorTests.java

@@ -20,6 +20,7 @@
 
 import org.springframework.boot.configurationprocessor.metadata.ConfigurationMetadata;
 import org.springframework.boot.configurationprocessor.metadata.Metadata;
+import org.springframework.boot.configurationsample.recursive.RecursiveProperties;
 import org.springframework.boot.configurationsample.simple.ClassWithNestedProperties;
 import org.springframework.boot.configurationsample.simple.DeprecatedFieldSingleProperty;
 import org.springframework.boot.configurationsample.simple.DeprecatedSingleProperty;
@@ -361,4 +362,9 @@ void constructorParameterPropertyWithInvalidDefaultValueOnCharacter() {
 				.withMessageContaining("Compilation failed");
 	}
 
+	@Test
+	void recursivePropertiesDoNotCauseAStackOverflow() {
+		compile(RecursiveProperties.class);
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/recursive/RecursiveProperties.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2012-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationsample.recursive;
+
+import org.springframework.boot.configurationsample.ConfigurationProperties;
+
+@ConfigurationProperties("prefix")
+public class RecursiveProperties {
+
+	private RecursiveProperties recursive;
+
+	public RecursiveProperties getRecursive() {
+		return this.recursive;
+	}
+
+	public void setRecursive(RecursiveProperties recursive) {
+		this.recursive = recursive;
+	}
+
+}