Fail explicitly in AOT transformations of instance supplier

It is by design not possible to generate code that handles
bean definitions with user-provided instance suppliers because
the JVM does not allow to get a stable reference reusable at
runtime on the lambda or method reference in the code generated
AOT.

Before this commit, such instance supplier was ignored.
After this commit, an IllegalArgumentException is thrown,
allowing projects to be aware this is not supported and enforce
related refactorings.

The related issue spring-projectsgh-29555 describes how this limitation could
be relaxed in the future.

Closes spring-projectsgh-29556

spring-beans/src/main/java/org/springframework/beans/factory/aot/BeanDefinitionMethodGenerator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -35,6 +35,7 @@
 import org.springframework.beans.factory.support.AutowireCandidateResolver;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.beans.factory.support.RegisteredBean;
+import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.core.MethodParameter;
 import org.springframework.javapoet.ClassName;
 import org.springframework.lang.Nullable;
@@ -45,6 +46,7 @@
  *
  * @author Phillip Webb
  * @author Stephane Nicoll
+ * @author Sebastien Deleuze
  * @since 6.0
  * @see BeanDefinitionMethodGeneratorFactory
  */
@@ -68,12 +70,17 @@ class BeanDefinitionMethodGenerator {
 	 * @param registeredBean the registered bean
 	 * @param currentPropertyName the current property name
 	 * @param aotContributions the AOT contributions
+	 * @throws IllegalArgumentException if the bean definition defines an instance supplier since this can't be supported for code generation
 	 */
 	BeanDefinitionMethodGenerator(
 			BeanDefinitionMethodGeneratorFactory methodGeneratorFactory,
 			RegisteredBean registeredBean, @Nullable String currentPropertyName,
 			List<BeanRegistrationAotContribution> aotContributions) {
 
+		RootBeanDefinition mbd = registeredBean.getMergedBeanDefinition();
+		if (mbd.getInstanceSupplier() != null) {
+			throw new IllegalArgumentException("Code generation is not supported for bean definitions declaring an instance supplier callback : " + mbd);
+		}
 		this.methodGeneratorFactory = methodGeneratorFactory;
 		this.registeredBean = registeredBean;
 		this.constructorOrFactoryMethod = registeredBean.resolveConstructorOrFactoryMethod();

spring-beans/src/test/java/org/springframework/beans/factory/aot/BeanDefinitionMethodGeneratorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -58,13 +58,15 @@
 import org.springframework.javapoet.ParameterizedTypeName;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 
 /**
  * Tests for {@link BeanDefinitionMethodGenerator} and
  * {@link DefaultBeanRegistrationCodeFragments}.
  *
  * @author Phillip Webb
  * @author Stephane Nicoll
+ * @author Sebastien Deleuze
  */
 class BeanDefinitionMethodGeneratorTests {
 
@@ -491,6 +493,14 @@ void generateBeanDefinitionMethodWhenBeanIsOfPrimitiveType() {
 		testBeanDefinitionMethodInCurrentFile(Boolean.class, beanDefinition);
 	}
 
+	@Test
+	void throwExceptionWithInstanceSupplier() {
+		RegisteredBean registeredBean = registerBean(new RootBeanDefinition(TestBean.class, TestBean::new));
+		assertThatIllegalArgumentException().isThrownBy(() -> new BeanDefinitionMethodGenerator(
+				this.methodGeneratorFactory, registeredBean, null,
+				Collections.emptyList()));
+	}
+
 	private void testBeanDefinitionMethodInCurrentFile(Class<?> targetType, RootBeanDefinition beanDefinition) {
 		RegisteredBean registeredBean = registerBean(new RootBeanDefinition(beanDefinition));
 		BeanDefinitionMethodGenerator generator = new BeanDefinitionMethodGenerator(