Polishing

See gh-29857

spring-expression/src/main/java/org/springframework/expression/spel/CompilablePropertyAccessor.java

@@ -19,7 +19,6 @@ package org.springframework.expression.spel;
 import org.springframework.asm.MethodVisitor;
 import org.springframework.asm.Opcodes;
 import org.springframework.expression.PropertyAccessor;
-import org.springframework.lang.Nullable;
 
 /**
  * A compilable {@link PropertyAccessor} is able to generate bytecode that represents
@@ -45,14 +44,10 @@ public interface CompilablePropertyAccessor extends PropertyAccessor, Opcodes {
 	 * Generate the bytecode that performs the access operation into the specified
 	 * {@link MethodVisitor} using context information from the {@link CodeFlow}
 	 * where necessary.
-	 * <p>Concrete implementations of {@code CompilablePropertyAccessor} typically
-	 * have access to the property name via other means (for example, supplied as
-	 * an argument when they were instantiated). Thus, the {@code propertyName}
-	 * supplied to this method may be {@code null}.
-	 * @param propertyName the name of the property, or {@code null} if not available
+	 * @param propertyName the name of the property
 	 * @param methodVisitor the ASM method visitor into which code should be generated
 	 * @param codeFlow the current state of the expression compiler
 	 */
-	void generateCode(@Nullable String propertyName, MethodVisitor methodVisitor, CodeFlow codeFlow);
+	void generateCode(String propertyName, MethodVisitor methodVisitor, CodeFlow codeFlow);
 
 }

spring-expression/src/main/java/org/springframework/expression/spel/ast/Indexer.java

@@ -213,16 +213,17 @@ public class Indexer extends SpelNodeImpl {
 		if (this.indexedType == IndexedType.ARRAY) {
 			return (this.exitTypeDescriptor != null);
 		}
-		else if (this.indexedType == IndexedType.LIST) {
-			return this.children[0].isCompilable();
+		SpelNodeImpl index = this.children[0];
+		if (this.indexedType == IndexedType.LIST) {
+			return index.isCompilable();
 		}
 		else if (this.indexedType == IndexedType.MAP) {
-			return (this.children[0] instanceof PropertyOrFieldReference || this.children[0].isCompilable());
+			return (index instanceof PropertyOrFieldReference || index.isCompilable());
 		}
 		else if (this.indexedType == IndexedType.OBJECT) {
 			// If the string name is changing, the accessor is clearly going to change.
 			// So compilation is only possible if the index expression is a StringLiteral.
-			return (getChild(0) instanceof StringLiteral &&
+			return (index instanceof StringLiteral &&
 					this.cachedReadAccessor instanceof CompilablePropertyAccessor compilablePropertyAccessor &&
 					compilablePropertyAccessor.isCompilable());
 		}
@@ -238,6 +239,7 @@ public class Indexer extends SpelNodeImpl {
 		}
 
 		SpelNodeImpl index = this.children[0];
+
 		if (this.indexedType == IndexedType.ARRAY) {
 			int insn = switch (this.exitTypeDescriptor) {
 				case "D" -> {
@@ -313,9 +315,14 @@ public class Indexer extends SpelNodeImpl {
 		}
 
 		else if (this.indexedType == IndexedType.OBJECT) {
+			if (!(index instanceof StringLiteral stringLiteral)) {
+				throw new IllegalStateException(
+						"Index expression must be a StringLiteral, but was: " + index.getClass().getName());
+			}
 			CompilablePropertyAccessor compilablePropertyAccessor = (CompilablePropertyAccessor) this.cachedReadAccessor;
 			Assert.state(compilablePropertyAccessor != null, "No cached read accessor");
-			compilablePropertyAccessor.generateCode(null, mv, cf);
+			String propertyName = (String) stringLiteral.getLiteralValue().getValue();
+			compilablePropertyAccessor.generateCode(propertyName, mv, cf);
 		}
 
 		cf.pushDescriptor(this.exitTypeDescriptor);

spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectivePropertyAccessor.java

@@ -712,7 +712,7 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
 		}
 
 		@Override
-		public void generateCode(@Nullable String propertyName, MethodVisitor mv, CodeFlow cf) {
+		public void generateCode(String propertyName, MethodVisitor mv, CodeFlow cf) {
 			Class<?> publicDeclaringClass = this.member.getDeclaringClass();
 			if (!Modifier.isPublic(publicDeclaringClass.getModifiers()) && this.originalMethod != null) {
 				publicDeclaringClass = ReflectionHelper.findPublicDeclaringClass(this.originalMethod);