Polishing

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

@@ -515,9 +515,9 @@ public class CodeFlow implements Opcodes {
 	}
 
 	/**
-	 * Determine whether the descriptor is for a primitive type.
+	 * Determine whether the descriptor is for a primitive type or {@code void}.
 	 * @param descriptor type descriptor
-	 * @return {@code true} if a primitive type
+	 * @return {@code true} if a primitive type or {@code void}
 	 */
 	public static boolean isPrimitive(@Nullable String descriptor) {
 		return (descriptor != null && descriptor.length() == 1);

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

@@ -60,7 +60,7 @@ public class MethodReference extends SpelNodeImpl {
 	private final String name;
 
 	@Nullable
-	private String originalPrimitiveExitTypeDescriptor;
+	private Character originalPrimitiveExitTypeDescriptor;
 
 	@Nullable
 	private volatile CachedMethodExecutor cachedExecutor;
@@ -260,7 +260,7 @@ public class MethodReference extends SpelNodeImpl {
 			Method method = reflectiveMethodExecutor.getMethod();
 			String descriptor = CodeFlow.toDescriptor(method.getReturnType());
 			if (this.nullSafe && CodeFlow.isPrimitive(descriptor)) {
-				this.originalPrimitiveExitTypeDescriptor = descriptor;
+				this.originalPrimitiveExitTypeDescriptor = descriptor.charAt(0);
 				this.exitTypeDescriptor = CodeFlow.toBoxedDescriptor(descriptor);
 			}
 			else {

spring-expression/src/main/java/org/springframework/expression/spel/standard/SpelCompiler.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.
@@ -184,8 +184,9 @@ public final class SpelCompiler implements Opcodes {
 		cf.finish();
 
 		byte[] data = cw.toByteArray();
-		// TODO need to make this conditionally occur based on a debug flag
-		// dump(expressionToCompile.toStringAST(), clazzName, data);
+		// TODO Save generated class files conditionally based on a debug flag.
+		// Source code for the following method resides in SpelCompilationCoverageTests.
+		// saveGeneratedClassFile(expressionToCompile.toStringAST(), className, data);
 		return loadClass(StringUtils.replace(className, "/", "."), data);
 	}
 

spring-expression/src/test/java/org/springframework/expression/spel/SpelCompilationCoverageTests.java

@@ -6255,4 +6255,19 @@ public class SpelCompilationCoverageTests extends AbstractExpressionTests {
 		}
 	}
 
+	// NOTE: saveGeneratedClassFile() can be copied to SpelCompiler and uncommented
+	// at the end of createExpressionClass(SpelNodeImpl) in order to review generated
+	// byte code for debugging purposes.
+	//
+	// private static void saveGeneratedClassFile(String stringAST, String className, byte[] data) {
+	//		Path path = Path.of("build", StringUtils.replace(className, "/", ".") + ".class");
+	//		System.out.println("Writing compiled SpEL expression [%s] to [%s]".formatted(stringAST, path.toAbsolutePath()));
+	//		try {
+	//			Files.copy(new ByteArrayInputStream(data), path);
+	//		}
+	//		catch (IOException ex) {
+	//			throw new UncheckedIOException(ex);
+	//		}
+	//	}
+
 }