Perform NullAway build-time checks in spring-expression

See gh-32475

gradle/spring-module.gradle

@@ -117,7 +117,7 @@ tasks.withType(JavaCompile).configureEach {
     options.errorprone {
     	disableAllChecks = true
         option("NullAway:CustomContractAnnotations", "org.springframework.lang.Contract")
-        option("NullAway:AnnotatedPackages", "org.springframework.core")
+        option("NullAway:AnnotatedPackages", "org.springframework.core,org.springframework.expression")
         option("NullAway:UnannotatedSubPackages", "org.springframework.instrument,org.springframework.context.index," +
 				"org.springframework.asm,org.springframework.cglib,org.springframework.objenesis," +
 				"org.springframework.javapoet,org.springframework.aot.nativex.substitution")

spring-core/src/main/java/org/springframework/core/convert/TypeDescriptor.java

@@ -30,6 +30,7 @@ import java.util.stream.Stream;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.annotation.AnnotatedElementUtils;
+import org.springframework.lang.Contract;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -562,6 +563,7 @@ public class TypeDescriptor implements Serializable {
 	 * @return the type descriptor
 	 */
 	@Nullable
+	@Contract("!null -> !null; null -> null")
 	public static TypeDescriptor forObject(@Nullable Object source) {
 		return (source != null ? valueOf(source.getClass()) : null);
 	}

spring-core/src/main/java/org/springframework/util/Assert.java

@@ -312,6 +312,7 @@ public abstract class Assert {
 	 * @param message the exception message to use if the assertion fails
 	 * @throws IllegalArgumentException if the object array is {@code null} or contains no elements
 	 */
+	@Contract("null, _ -> fail")
 	public static void notEmpty(@Nullable Object[] array, String message) {
 		if (ObjectUtils.isEmpty(array)) {
 			throw new IllegalArgumentException(message);
@@ -330,6 +331,7 @@ public abstract class Assert {
 	 * @throws IllegalArgumentException if the object array is {@code null} or contains no elements
 	 * @since 5.0
 	 */
+	@Contract("null, _ -> fail")
 	public static void notEmpty(@Nullable Object[] array, Supplier<String> messageSupplier) {
 		if (ObjectUtils.isEmpty(array)) {
 			throw new IllegalArgumentException(nullSafeGet(messageSupplier));

spring-core/src/main/java/org/springframework/util/ObjectUtils.java

@@ -27,6 +27,7 @@ import java.util.Optional;
 import java.util.StringJoiner;
 import java.util.TimeZone;
 
+import org.springframework.lang.Contract;
 import org.springframework.lang.Nullable;
 
 /**
@@ -110,6 +111,7 @@ public abstract class ObjectUtils {
 	 * @param array the array to check
 	 * @see #isEmpty(Object)
 	 */
+	@Contract("null -> true")
 	public static boolean isEmpty(@Nullable Object[] array) {
 		return (array == null || array.length == 0);
 	}
@@ -331,6 +333,7 @@ public abstract class ObjectUtils {
 	 * @see Object#equals(Object)
 	 * @see java.util.Arrays#equals
 	 */
+	@Contract("null, null -> true; null, _ -> false; _, null -> false")
 	public static boolean nullSafeEquals(@Nullable Object o1, @Nullable Object o2) {
 		if (o1 == o2) {
 			return true;

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

@@ -28,6 +28,7 @@ import java.util.Map;
 import org.springframework.asm.ClassWriter;
 import org.springframework.asm.MethodVisitor;
 import org.springframework.asm.Opcodes;
+import org.springframework.lang.Contract;
 import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.CollectionUtils;
@@ -583,6 +584,7 @@ public class CodeFlow implements Opcodes {
 	 * @param descriptor type descriptor
 	 * @return {@code true} if the descriptor is boolean compatible
 	 */
+	@Contract("null -> false")
 	public static boolean isBooleanCompatible(@Nullable String descriptor) {
 		return (descriptor != null && (descriptor.equals("Z") || descriptor.equals("Ljava/lang/Boolean")));
 	}
@@ -592,6 +594,7 @@ public class CodeFlow implements Opcodes {
 	 * @param descriptor type descriptor
 	 * @return {@code true} if a primitive type or {@code void}
 	 */
+	@Contract("null -> false")
 	public static boolean isPrimitive(@Nullable String descriptor) {
 		return (descriptor != null && descriptor.length() == 1);
 	}
@@ -601,6 +604,7 @@ public class CodeFlow implements Opcodes {
 	 * @param descriptor the descriptor for a possible primitive array
 	 * @return {@code true} if the descriptor a primitive array
 	 */
+	@Contract("null -> false")
 	public static boolean isPrimitiveArray(@Nullable String descriptor) {
 		if (descriptor == null) {
 			return false;
@@ -653,6 +657,7 @@ public class CodeFlow implements Opcodes {
 	 * @param descriptor the descriptor for a type
 	 * @return {@code true} if the descriptor is for a supported numeric type or boolean
 	 */
+	@Contract("null -> false")
 	public static boolean isPrimitiveOrUnboxableSupportedNumberOrBoolean(@Nullable String descriptor) {
 		if (descriptor == null) {
 			return false;
@@ -670,6 +675,7 @@ public class CodeFlow implements Opcodes {
 	 * @param descriptor the descriptor for a type
 	 * @return {@code true} if the descriptor is for a supported numeric type
 	 */
+	@Contract("null -> false")
 	public static boolean isPrimitiveOrUnboxableSupportedNumber(@Nullable String descriptor) {
 		if (descriptor == null) {
 			return false;
@@ -690,6 +696,7 @@ public class CodeFlow implements Opcodes {
 	 * @param number the number to check
 	 * @return {@code true} if it is an {@link Integer}, {@link Short} or {@link Byte}
 	 */
+	@Contract("null -> false")
 	public static boolean isIntegerForNumericOp(Number number) {
 		return (number instanceof Integer || number instanceof Short || number instanceof Byte);
 	}

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

@@ -325,6 +325,7 @@ public class Indexer extends SpelNodeImpl {
 			CompilablePropertyAccessor compilablePropertyAccessor = (CompilablePropertyAccessor) this.cachedReadAccessor;
 			Assert.state(compilablePropertyAccessor != null, "No cached read accessor");
 			String propertyName = (String) stringLiteral.getLiteralValue().getValue();
+			Assert.state(propertyName != null, "No property name");
 			compilablePropertyAccessor.generateCode(propertyName, mv, cf);
 		}
 
@@ -565,6 +566,7 @@ public class Indexer extends SpelNodeImpl {
 		}
 
 		@Override
+		@SuppressWarnings("NullAway")
 		public TypedValue getValue() {
 			Class<?> targetObjectRuntimeClass = getObjectClass(this.targetObject);
 			try {
@@ -603,6 +605,7 @@ public class Indexer extends SpelNodeImpl {
 		}
 
 		@Override
+		@SuppressWarnings("NullAway")
 		public void setValue(@Nullable Object newValue) {
 			Class<?> contextObjectClass = getObjectClass(this.targetObject);
 			try {

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

@@ -25,6 +25,7 @@ import org.springframework.expression.spel.ExpressionState;
 import org.springframework.expression.spel.SpelEvaluationException;
 import org.springframework.expression.spel.SpelMessage;
 import org.springframework.expression.spel.support.BooleanTypedValue;
+import org.springframework.lang.Contract;
 import org.springframework.lang.Nullable;
 
 /**
@@ -64,6 +65,7 @@ public class OpAnd extends Operator {
 		}
 	}
 
+	@Contract("null -> fail")
 	private void assertValueNotNull(@Nullable Boolean value) {
 		if (value == null) {
 			throw new SpelEvaluationException(SpelMessage.TYPE_CONVERSION_ERROR, "null", "boolean");

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

@@ -68,19 +68,17 @@ public class OpEQ extends Operator {
 		cf.loadEvaluationContext(mv);
 		String leftDesc = getLeftOperand().exitTypeDescriptor;
 		String rightDesc = getRightOperand().exitTypeDescriptor;
-		boolean leftPrim = CodeFlow.isPrimitive(leftDesc);
-		boolean rightPrim = CodeFlow.isPrimitive(rightDesc);
 
 		cf.enterCompilationScope();
 		getLeftOperand().generateCode(mv, cf);
 		cf.exitCompilationScope();
-		if (leftPrim) {
+		if (CodeFlow.isPrimitive(leftDesc)) {
 			CodeFlow.insertBoxIfNecessary(mv, leftDesc.charAt(0));
 		}
 		cf.enterCompilationScope();
 		getRightOperand().generateCode(mv, cf);
 		cf.exitCompilationScope();
-		if (rightPrim) {
+		if (CodeFlow.isPrimitive(rightDesc)) {
 			CodeFlow.insertBoxIfNecessary(mv, rightDesc.charAt(0));
 		}
 

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

@@ -69,19 +69,17 @@ public class OpNE extends Operator {
 		cf.loadEvaluationContext(mv);
 		String leftDesc = getLeftOperand().exitTypeDescriptor;
 		String rightDesc = getRightOperand().exitTypeDescriptor;
-		boolean leftPrim = CodeFlow.isPrimitive(leftDesc);
-		boolean rightPrim = CodeFlow.isPrimitive(rightDesc);
 
 		cf.enterCompilationScope();
 		getLeftOperand().generateCode(mv, cf);
 		cf.exitCompilationScope();
-		if (leftPrim) {
+		if (CodeFlow.isPrimitive(leftDesc)) {
 			CodeFlow.insertBoxIfNecessary(mv, leftDesc.charAt(0));
 		}
 		cf.enterCompilationScope();
 		getRightOperand().generateCode(mv, cf);
 		cf.exitCompilationScope();
-		if (rightPrim) {
+		if (CodeFlow.isPrimitive(rightDesc)) {
 			CodeFlow.insertBoxIfNecessary(mv, rightDesc.charAt(0));
 		}
 

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

@@ -24,6 +24,7 @@ import org.springframework.expression.spel.ExpressionState;
 import org.springframework.expression.spel.SpelEvaluationException;
 import org.springframework.expression.spel.SpelMessage;
 import org.springframework.expression.spel.support.BooleanTypedValue;
+import org.springframework.lang.Contract;
 import org.springframework.lang.Nullable;
 
 /**
@@ -63,6 +64,7 @@ public class OpOr extends Operator {
 		}
 	}
 
+	@Contract("null -> fail")
 	private void assertValueNotNull(@Nullable Boolean value) {
 		if (value == null) {
 			throw new SpelEvaluationException(SpelMessage.TYPE_CONVERSION_ERROR, "null", "boolean");

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

@@ -352,6 +352,7 @@ public abstract class Operator extends SpelNodeImpl {
 		 * @param rightActualDescriptor the dynamic/runtime right object descriptor
 		 * @return a DescriptorComparison object indicating the type of compatibility, if any
 		 */
+		@SuppressWarnings("NullAway")
 		public static DescriptorComparison checkNumericCompatibility(
 				@Nullable String leftDeclaredDescriptor, @Nullable String rightDeclaredDescriptor,
 				@Nullable String leftActualDescriptor, @Nullable String rightActualDescriptor) {

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

@@ -134,7 +134,7 @@ public class PropertyOrFieldReference extends SpelNodeImpl {
 				// 'simple' object
 				try {
 					if (isWritableProperty(this.name,contextObject, evalContext)) {
-						Class<?> clazz = result.getTypeDescriptor().getType();
+						Class<?> clazz = resultDescriptor.getType();
 						Object newObject = ReflectionUtils.accessibleConstructor(clazz).newInstance();
 						writeProperty(contextObject, evalContext, this.name, newObject);
 						result = readProperty(contextObject, evalContext, this.name);
@@ -142,11 +142,11 @@ public class PropertyOrFieldReference extends SpelNodeImpl {
 				}
 				catch (InvocationTargetException ex) {
 					throw new SpelEvaluationException(getStartPosition(), ex.getTargetException(),
-							SpelMessage.UNABLE_TO_DYNAMICALLY_CREATE_OBJECT, result.getTypeDescriptor().getType());
+							SpelMessage.UNABLE_TO_DYNAMICALLY_CREATE_OBJECT, resultDescriptor.getType());
 				}
 				catch (Throwable ex) {
 					throw new SpelEvaluationException(getStartPosition(), ex,
-							SpelMessage.UNABLE_TO_DYNAMICALLY_CREATE_OBJECT, result.getTypeDescriptor().getType());
+							SpelMessage.UNABLE_TO_DYNAMICALLY_CREATE_OBJECT, resultDescriptor.getType());
 				}
 			}
 		}

spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java

@@ -76,6 +76,7 @@ import org.springframework.expression.spel.ast.StringLiteral;
 import org.springframework.expression.spel.ast.Ternary;
 import org.springframework.expression.spel.ast.TypeReference;
 import org.springframework.expression.spel.ast.VariableReference;
+import org.springframework.lang.Contract;
 import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 
@@ -164,6 +165,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 	//	    | (QMARK^ expression COLON! expression)
 	//      | (ELVIS^ expression))?;
 	@Nullable
+	@SuppressWarnings("NullAway")
 	private SpelNodeImpl eatExpression() {
 		SpelNodeImpl expr = eatLogicalOrExpression();
 		Token t = peekToken();
@@ -274,6 +276,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 
 	//sumExpression: productExpression ( (PLUS^ | MINUS^) productExpression)*;
 	@Nullable
+	@SuppressWarnings("NullAway")
 	private SpelNodeImpl eatSumExpression() {
 		SpelNodeImpl expr = eatProductExpression();
 		while (peekToken(TokenKind.PLUS, TokenKind.MINUS, TokenKind.INC)) {
@@ -313,6 +316,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 
 	// powerExpr  : unaryExpression (POWER^ unaryExpression)? (INC || DEC) ;
 	@Nullable
+	@SuppressWarnings("NullAway")
 	private SpelNodeImpl eatPowerIncDecExpression() {
 		SpelNodeImpl expr = eatUnaryExpression();
 		if (peekToken(TokenKind.POWER)) {
@@ -333,6 +337,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 
 	// unaryExpression: (PLUS^ | MINUS^ | BANG^ | INC^ | DEC^) unaryExpression | primaryExpression ;
 	@Nullable
+	@SuppressWarnings("NullAway")
 	private SpelNodeImpl eatUnaryExpression() {
 		if (peekToken(TokenKind.NOT, TokenKind.PLUS, TokenKind.MINUS)) {
 			Token t = takeToken();
@@ -755,6 +760,7 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 				qualifiedIdPieces.getLast().getEndPosition(), qualifiedIdPieces.toArray(new SpelNodeImpl[0]));
 	}
 
+	@Contract("null -> false")
 	private boolean isValidQualifiedId(@Nullable Token node) {
 		if (node == null || node.kind == TokenKind.LITERAL_STRING) {
 			return false;
@@ -1040,17 +1046,20 @@ class InternalSpelExpressionParser extends TemplateAwareExpressionParser {
 		return t.kind.toString().toLowerCase();
 	}
 
+	@Contract("_, null, _ -> fail; _, _, null -> fail")
 	private void checkOperands(Token token, @Nullable SpelNodeImpl left, @Nullable SpelNodeImpl right) {
 		checkLeftOperand(token, left);
 		checkRightOperand(token, right);
 	}
 
+	@Contract("_, null -> fail")
 	private void checkLeftOperand(Token token, @Nullable SpelNodeImpl operandExpression) {
 		if (operandExpression == null) {
 			throw internalException(token.startPos, SpelMessage.LEFT_OPERAND_PROBLEM);
 		}
 	}
 
+	@Contract("_, null -> fail")
 	private void checkRightOperand(Token token, @Nullable SpelNodeImpl operandExpression) {
 		if (operandExpression == null) {
 			throw internalException(token.startPos, SpelMessage.RIGHT_OPERAND_PROBLEM);

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

@@ -155,6 +155,7 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
 	}
 
 	@Override
+	@SuppressWarnings("NullAway")
 	public TypedValue read(EvaluationContext context, @Nullable Object target, String name) throws AccessException {
 		Assert.state(target != null, "Target must not be null");
 		Class<?> type = (target instanceof Class<?> clazz ? clazz : target.getClass());
@@ -515,6 +516,7 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
 	 * <p>Note: An optimized accessor is currently only usable for read attempts.
 	 * Do not call this method if you need a read-write accessor.
 	 */
+	@SuppressWarnings("NullAway")
 	public PropertyAccessor createOptimalAccessor(EvaluationContext context, @Nullable Object target, String name) {
 		// Don't be clever for arrays or a null target...
 		if (target == null) {