From 1e73439955544f3ee7b224f5bc7332f2ab266e49 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Deleuze?= <sdeleuze@vmware.com>
Date: Fri, 11 Aug 2023 16:52:44 +0200
Subject: [PATCH] Support Kotlin value class properties in SpEL

This commit adds support for inlined Kotlin value
class properties in SpEL by leveraging Kotlin
reflection instead of Java reflection broken
by the mangled method name.

Closes gh-30468
---
 spring-expression/spring-expression.gradle    |  1 +
 .../support/ReflectivePropertyAccessor.java   | 39 ++++++++++++++++++-
 .../expression/spel/SpelReproKotlinTests.kt   | 21 ++++++++++
 3 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/spring-expression/spring-expression.gradle b/spring-expression/spring-expression.gradle
index 920f7c7bc0..4b31d5b6f5 100644
--- a/spring-expression/spring-expression.gradle
+++ b/spring-expression/spring-expression.gradle
@@ -4,6 +4,7 @@ apply plugin: "kotlin"
 
 dependencies {
 	api(project(":spring-core"))
+	optional("org.jetbrains.kotlin:kotlin-reflect")
 	testImplementation(testFixtures(project(":spring-core")))
 	testImplementation("org.jetbrains.kotlin:kotlin-reflect")
 	testImplementation("org.jetbrains.kotlin:kotlin-stdlib")
diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectivePropertyAccessor.java b/spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectivePropertyAccessor.java
index fa2cd34fbc..d9e6dcb373 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectivePropertyAccessor.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectivePropertyAccessor.java
@@ -27,7 +27,15 @@ import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
+import kotlin.jvm.JvmClassMappingKt;
+import kotlin.reflect.KClass;
+import kotlin.reflect.KMutableProperty;
+import kotlin.reflect.KProperty;
+import kotlin.reflect.full.KClasses;
+import kotlin.reflect.jvm.ReflectJvmMapping;
+
 import org.springframework.asm.MethodVisitor;
+import org.springframework.core.KotlinDetector;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.convert.Property;
 import org.springframework.core.convert.TypeDescriptor;
@@ -55,6 +63,7 @@ import org.springframework.util.StringUtils;
  * @author Juergen Hoeller
  * @author Phillip Webb
  * @author Sam Brannen
+ * @author Sebastien Deleuze
  * @since 3.0
  * @see StandardEvaluationContext
  * @see SimpleEvaluationContext
@@ -401,7 +410,8 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
 		Method[] methods = getSortedMethods(clazz);
 		for (String methodSuffix : methodSuffixes) {
 			for (Method method : methods) {
-				if (isCandidateForProperty(method, clazz) && method.getName().equals(prefix + methodSuffix) &&
+				if (isCandidateForProperty(method, clazz) &&
+						(method.getName().equals(prefix + methodSuffix) || isKotlinProperty(method, methodSuffix)) &&
 						method.getParameterCount() == numberOfParams &&
 						(!mustBeStatic || Modifier.isStatic(method.getModifiers())) &&
 						(requiredReturnTypes.isEmpty() || requiredReturnTypes.contains(method.getReturnType()))) {
@@ -557,6 +567,13 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
 		return this;
 	}
 
+	private static boolean isKotlinProperty(Method method, String methodSuffix) {
+		Class<?> clazz = method.getDeclaringClass();
+		return KotlinDetector.isKotlinReflectPresent() &&
+				KotlinDetector.isKotlinType(clazz)  &&
+				KotlinDelegate.isKotlinProperty(method, methodSuffix);
+	}
+
 
 	/**
 	 * Captures the member (method/field) to call reflectively to access a property value
@@ -755,4 +772,24 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
 		}
 	}
 
+	/**
+	 * Inner class to avoid a hard dependency on Kotlin at runtime.
+	 */
+	private static class KotlinDelegate {
+
+		public static boolean isKotlinProperty(Method method, String methodSuffix) {
+			KClass<?> kClass = JvmClassMappingKt.getKotlinClass(method.getDeclaringClass());
+			for (KProperty<?> property : KClasses.getMemberProperties(kClass)) {
+				if (methodSuffix.equalsIgnoreCase(property.getName()) &&
+						(method.equals(ReflectJvmMapping.getJavaGetter(property)) ||
+								property instanceof KMutableProperty<?> mutableProperty &&
+										method.equals(ReflectJvmMapping.getJavaSetter(mutableProperty)))) {
+					return true;
+				}
+			}
+			return false;
+		}
+
+	}
+
 }
diff --git a/spring-expression/src/test/kotlin/org/springframework/expression/spel/SpelReproKotlinTests.kt b/spring-expression/src/test/kotlin/org/springframework/expression/spel/SpelReproKotlinTests.kt
index 65260a1ef4..24fc744adf 100644
--- a/spring-expression/src/test/kotlin/org/springframework/expression/spel/SpelReproKotlinTests.kt
+++ b/spring-expression/src/test/kotlin/org/springframework/expression/spel/SpelReproKotlinTests.kt
@@ -55,6 +55,20 @@ class SpelReproKotlinTests {
 		assertThat(expr.getValue(context, Boolean::class.java)).isFalse()
 	}
 
+	@Test
+	fun `gh-30468 Unmangle Kotlin inlined class getter`() {
+		context.setVariable("something", Something(UUID(123), "name"))
+		val expr = parser.parseExpression("#something.id")
+		assertThat(expr.getValue(context, Int::class.java)).isEqualTo(123)
+	}
+
+	@Test
+	fun `gh-30468 Unmangle Kotlin inlined class setter`() {
+		context.setVariable("something", Something(UUID(123), "name"))
+		val expr = parser.parseExpression("#something.id = 456")
+		assertThat(expr.getValue(context, Int::class.java)).isEqualTo(456)
+	}
+
 	@Suppress("UNUSED_PARAMETER")
 	class Config {
 
@@ -71,4 +85,11 @@ class SpelReproKotlinTests {
 		}
 
 	}
+
+	@JvmInline value class UUID(val value: Int)
+
+	data class Something(
+		var id: UUID,
+		var name: String,
+	)
 }