Allow target type of a cglib proxy to be visible

This commit updates the hints of a Cglib proxy's target type so that
methods can be invoked and constructors can be introspected. The former
is needed as a cglib proxy invokes the target type via reflection. As
for that latter, this is required at least by
Enhancer#filterConstructors.

See gh-28954

Author: snicoll

spring-context/src/main/java/org/springframework/context/aot/GeneratedClassHandler.java

@@ -43,6 +43,10 @@ class GeneratedClassHandler implements BiConsumer<String, byte[]> {
 					MemberCategory.INVOKE_DECLARED_METHODS,
 					MemberCategory.DECLARED_FIELDS);
 
+	private static final Consumer<Builder> asCglibProxyTargetType = hint ->
+			hint.withMembers(MemberCategory.INTROSPECT_DECLARED_CONSTRUCTORS,
+					MemberCategory.INVOKE_DECLARED_METHODS);
+
 	private final RuntimeHints runtimeHints;
 
 	private final GeneratedFiles generatedFiles;
@@ -54,9 +58,18 @@ class GeneratedClassHandler implements BiConsumer<String, byte[]> {
 
 	@Override
 	public void accept(String className, byte[] content) {
-		this.runtimeHints.reflection().registerType(TypeReference.of(className), asCglibProxy);
+		this.runtimeHints.reflection().registerType(TypeReference.of(className), asCglibProxy)
+				.registerType(TypeReference.of(getTargetTypeClassName(className)), asCglibProxyTargetType);
 		String path = className.replace(".", "/") + ".class";
 		this.generatedFiles.addFile(Kind.CLASS, path, new ByteArrayResource(content));
 	}
 
+	private String getTargetTypeClassName(String proxyClassName) {
+		int index = proxyClassName.indexOf("$$SpringCGLIB$$");
+		if (index == -1) {
+			throw new IllegalArgumentException("Failed to extract target type from " + proxyClassName);
+		}
+		return proxyClassName.substring(0, index);
+	}
+
 }

spring-context/src/test/java/org/springframework/context/aot/GeneratedClassHandlerTests.java

@@ -30,6 +30,7 @@
 import org.springframework.core.testfixture.aot.generate.TestGenerationContext;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 
 /**
  * Tests for {@link GeneratedClassHandler}.
@@ -50,23 +51,40 @@ public GeneratedClassHandlerTests() {
 	}
 
 	@Test
-	void handlerGenerateRuntimeHints() {
-		String className = "com.example.Test$$Proxy$$1";
+	void handlerGenerateRuntimeHintsForProxy() {
+		String className = "com.example.Test$$SpringCGLIB$$0";
 		this.handler.accept(className, TEST_CONTENT);
 		assertThat(RuntimeHintsPredicates.reflection().onType(TypeReference.of(className))
 				.withMemberCategories(MemberCategory.INVOKE_DECLARED_CONSTRUCTORS,
 						MemberCategory.INVOKE_DECLARED_METHODS, MemberCategory.DECLARED_FIELDS))
 				.accepts(this.generationContext.getRuntimeHints());
 	}
 
+	@Test
+	void handlerGenerateRuntimeHintsForTargetType() {
+		String className = "com.example.Test$$SpringCGLIB$$0";
+		this.handler.accept(className, TEST_CONTENT);
+		assertThat(RuntimeHintsPredicates.reflection().onType(TypeReference.of("com.example.Test"))
+				.withMemberCategories(MemberCategory.INTROSPECT_DECLARED_CONSTRUCTORS,
+						MemberCategory.INVOKE_DECLARED_METHODS))
+				.accepts(this.generationContext.getRuntimeHints());
+	}
+
+	@Test
+	void handlerFailsWithInvalidProxyClassName() {
+		String className = "com.example.Test$$AnotherProxy$$0";
+		assertThatIllegalArgumentException().isThrownBy(() -> this.handler.accept(className, TEST_CONTENT))
+				.withMessageContaining("Failed to extract target type");
+	}
+
 	@Test
 	void handlerRegisterGeneratedClass() throws IOException {
-		String className = "com.example.Test$$Proxy$$1";
+		String className = "com.example.Test$$SpringCGLIB$$0";
 		this.handler.accept(className, TEST_CONTENT);
 		InMemoryGeneratedFiles generatedFiles = this.generationContext.getGeneratedFiles();
 		assertThat(generatedFiles.getGeneratedFiles(Kind.SOURCE)).isEmpty();
 		assertThat(generatedFiles.getGeneratedFiles(Kind.RESOURCE)).isEmpty();
-		String expectedPath = "com/example/Test$$Proxy$$1.class";
+		String expectedPath = "com/example/Test$$SpringCGLIB$$0.class";
 		assertThat(generatedFiles.getGeneratedFiles(Kind.CLASS)).containsOnlyKeys(expectedPath);
 		assertContent(generatedFiles.getGeneratedFiles(Kind.CLASS).get(expectedPath), TEST_CONTENT);
 	}