Restrict lenient nested matching to immediate type variable

Includes fix for matching multiple wildcard bounds properly.

Closes gh-34119
Closes gh-34234

Author: jhoeller

spring-core/src/main/java/org/springframework/core/ResolvableType.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -410,8 +410,9 @@ else if (!exactMatch) {
 				}
 				matchedBefore.put(this.type, other.type);
 				for (int i = 0; i < ourGenerics.length; i++) {
-					if (!ourGenerics[i].isAssignableFrom(otherGenerics[i],
-							!other.hasUnresolvableGenerics(), matchedBefore, upUntilUnresolvable)) {
+					ResolvableType otherGeneric = otherGenerics[i];
+					if (!ourGenerics[i].isAssignableFrom(otherGeneric,
+							!otherGeneric.isUnresolvableTypeVariable(), matchedBefore, upUntilUnresolvable)) {
 						return false;
 					}
 				}
@@ -1729,8 +1730,16 @@ public boolean isSameKind(WildcardBounds bounds) {
 		 * @return {@code true} if these bounds are assignable from all types
 		 */
 		public boolean isAssignableFrom(ResolvableType[] types, @Nullable Map<Type, Type> matchedBefore) {
-			for (ResolvableType type : types) {
-				if (!isAssignableFrom(type, matchedBefore)) {
+			for (ResolvableType bound : this.bounds) {
+				boolean matched = false;
+				for (ResolvableType type : types) {
+					if (this.kind == Kind.UPPER ? bound.isAssignableFrom(type, false, matchedBefore, false) :
+							type.isAssignableFrom(bound, false, matchedBefore, false)) {
+						matched = true;
+						break;
+					}
+				}
+				if (!matched) {
 					return false;
 				}
 			}

spring-core/src/test/java/org/springframework/core/ResolvableTypeTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -1189,10 +1189,11 @@ void isAssignableFromForComplexWildcards() throws Exception {
 	}
 
 	@Test
-	void isAssignableFromForUnresolvedWildcards() {
+	void isAssignableFromForUnresolvedWildcard() {
 		ResolvableType wildcard = ResolvableType.forInstance(new Wildcard<>());
 		ResolvableType wildcardFixed = ResolvableType.forInstance(new WildcardFixed());
-		ResolvableType wildcardConcrete = ResolvableType.forClassWithGenerics(Wildcard.class, Number.class);
+		ResolvableType wildcardConcrete = ResolvableType.forClassWithGenerics(Wildcard.class, CharSequence.class);
+		ResolvableType wildcardConsumer = ResolvableType.forInstance(new WildcardConsumer<>());
 
 		assertThat(wildcard.isAssignableFrom(wildcardFixed)).isTrue();
 		assertThat(wildcard.isAssignableFromResolvedPart(wildcardFixed)).isTrue();
@@ -1206,6 +1207,38 @@ void isAssignableFromForUnresolvedWildcards() {
 		assertThat(wildcardConcrete.isAssignableFromResolvedPart(wildcard)).isTrue();
 		assertThat(wildcardConcrete.isAssignableFrom(wildcardFixed)).isFalse();
 		assertThat(wildcardConcrete.isAssignableFromResolvedPart(wildcardFixed)).isFalse();
+		assertThat(wildcardConsumer.as(Consumer.class).getGeneric().isAssignableFrom(wildcard)).isFalse();
+		assertThat(wildcardConsumer.as(Consumer.class).getGeneric().isAssignableFromResolvedPart(wildcard)).isTrue();
+	}
+
+	@Test
+	void isAssignableFromForUnresolvedDoubleWildcard() {
+		ResolvableType wildcard = ResolvableType.forInstance(new DoubleWildcard<>());
+		ResolvableType wildcardFixed = ResolvableType.forInstance(new DoubleWildcardFixed());
+		ResolvableType wildcardConsumer = ResolvableType.forInstance(new DoubleWildcardConsumer<>());
+
+		assertThat(wildcard.isAssignableFrom(wildcardFixed)).isTrue();
+		assertThat(wildcard.isAssignableFromResolvedPart(wildcardFixed)).isTrue();
+		assertThat(wildcardFixed.isAssignableFrom(wildcard)).isFalse();
+		assertThat(wildcardFixed.isAssignableFromResolvedPart(wildcard)).isFalse();
+		assertThat(wildcardConsumer.as(Consumer.class).getGeneric().isAssignableFrom(wildcard)).isTrue();
+		assertThat(wildcardConsumer.as(Consumer.class).getGeneric().isAssignableFromResolvedPart(wildcard)).isTrue();
+	}
+
+	@Test
+	void strictGenericsMatching() {
+		ResolvableType consumerUnresolved = ResolvableType.forClass(Consumer.class);
+		ResolvableType consumerObject = ResolvableType.forClassWithGenerics(Consumer.class, Object.class);
+		ResolvableType consumerNestedUnresolved = ResolvableType.forClassWithGenerics(Consumer.class, ResolvableType.forClass(Consumer.class));
+
+		assertThat(consumerUnresolved.isAssignableFrom(consumerObject)).isTrue();
+		assertThat(consumerUnresolved.isAssignableFromResolvedPart(consumerObject)).isTrue();
+		assertThat(consumerObject.isAssignableFrom(consumerUnresolved)).isTrue();
+		assertThat(consumerObject.isAssignableFromResolvedPart(consumerUnresolved)).isTrue();
+		assertThat(consumerUnresolved.isAssignableFrom(consumerNestedUnresolved)).isTrue();
+		assertThat(consumerUnresolved.isAssignableFromResolvedPart(consumerNestedUnresolved)).isTrue();
+		assertThat(consumerObject.isAssignableFrom(consumerNestedUnresolved)).isFalse();
+		assertThat(consumerObject.isAssignableFromResolvedPart(consumerNestedUnresolved)).isFalse();
 	}
 
 	@Test
@@ -1752,12 +1785,26 @@ public class MyCollectionSuperclassType extends MySuperclassType<Collection<Stri
 	}
 
 
-	public class Wildcard<T extends Number> {
+	public class Wildcard<T extends CharSequence> {
+	}
+
+	public class WildcardFixed extends Wildcard<String> {
+	}
+
+	public class WildcardConsumer<T extends CharSequence & Serializable> implements Consumer<Wildcard<T>> {
 	}
 
-	public class WildcardFixed extends Wildcard<Integer> {
+
+	public class DoubleWildcard<T extends CharSequence & Serializable> {
 	}
 
+	public class DoubleWildcardFixed extends DoubleWildcard<String> {
+	}
+
+	public class DoubleWildcardConsumer<T extends CharSequence & Serializable> implements Consumer<DoubleWildcard<T>> {
+	}
+
+
 
 	interface VariableNameSwitch<V, K> extends MultiValueMap<K, V> {
 	}