@ToString, @Getter, and @XArgsConstructor now work on, and are legal on, enums. Docs have been updated.

Behaviour of @XArgsConstructor when its placement makes no sense (i.e. when annotating an interface with them) is no longer 'throw weird errors', but has been brought in line with the others: A nice error message is generated.

Fixes issue #175

doc/changelog.markdown

@@ -5,6 +5,7 @@ Lombok Changelog
 * FEATURE: Added support for several logging frameworks by the `@Log` annotation.
 * FEATURE: Lombok now supports post-compile transformers. [Issue #144](http://code.google.com/p/projectlombok/issues/detail?id=144)
 * FEATURE: Using `@SneakyThrows` no longer requires a runtime dependency on lombok.jar. In fact, any call to {@code Lombok.sneakyThrows(ex)} is optimized at the bytecode level and no longer requires you to actually have lombok.jar or lombok-runtime.jar on the classpath.
+ * FEATURE: @XArgsConstructor, @Getter, and @ToString can now be used on enum declarations. Previously, behaviour of these annotations on enums was undefined.
 * BUGFIX: `@Setter` and `@Getter` can now be applied to static fields again (was broken in v0.9.3 only). [Issue #136](http://code.google.com/p/projectlombok/issues/detail?id=136)
 * BUGFIX: delombok added type parameters to constructors that mirror the type's own type parameters. This resulted in delombok turning any generated constructor that takes at least 1 parameter of type 'T' into something that didn't compile, and to boot, a confusing error message ('T is not compatible with T'). This is now fixed. [Issue #140](http://code.google.com/p/projectlombok/issues/detail?id=140)
 * BUGFIX: Add null check for `@Cleanup` [Issue #154](http://code.google.com/p/projectlombok/issues/detail?id=154)

src/core/lombok/eclipse/handlers/EclipseHandlerUtil.java

@@ -293,6 +293,24 @@ public class EclipseHandlerUtil {
 		NOT_EXISTS, EXISTS_BY_USER, EXISTS_BY_LOMBOK;
 	}
 	
+	/**
+	 * Checks if the field should be included in operations that work on 'all' fields:
+	 *    If the field is static, or starts with a '$', or is actually an enum constant, 'false' is returned, indicating you should skip it.
+	 */
+	public static boolean filterField(FieldDeclaration declaration) {
+		// Skip the fake fields that represent enum constants.
+		if (declaration.initialization instanceof AllocationExpression &&
+				((AllocationExpression)declaration.initialization).enumConstant != null) return false;
+		
+		// Skip fields that start with $
+		if (declaration.name.length > 0 && declaration.name[0] == '$') return false;
+		
+		// Skip static fields.
+		if ((declaration.modifiers & ClassFileConstants.AccStatic) != 0) return false;
+		
+		return true;
+	}
+	
 	/**
 	 * Checks if there is a field with the provided name.
 	 * 

src/core/lombok/eclipse/handlers/HandleConstructor.java

@@ -75,6 +75,7 @@ public class HandleConstructor {
 	public static class HandleNoArgsConstructor implements EclipseAnnotationHandler<NoArgsConstructor> {
 		@Override public boolean handle(AnnotationValues<NoArgsConstructor> annotation, Annotation ast, EclipseNode annotationNode) {
 			EclipseNode typeNode = annotationNode.up();
+			if (!checkLegality(typeNode, annotationNode, NoArgsConstructor.class.getSimpleName())) return true;
 			NoArgsConstructor ann = annotation.getInstance();
 			AccessLevel level = ann.access();
 			String staticName = ann.staticName();
@@ -89,6 +90,7 @@ public class HandleConstructor {
 	public static class HandleRequiredArgsConstructor implements EclipseAnnotationHandler<RequiredArgsConstructor> {
 		@Override public boolean handle(AnnotationValues<RequiredArgsConstructor> annotation, Annotation ast, EclipseNode annotationNode) {
 			EclipseNode typeNode = annotationNode.up();
+			if (!checkLegality(typeNode, annotationNode, RequiredArgsConstructor.class.getSimpleName())) return true;
 			RequiredArgsConstructor ann = annotation.getInstance();
 			AccessLevel level = ann.access();
 			String staticName = ann.staticName();
@@ -105,10 +107,7 @@ public class HandleConstructor {
 		for (EclipseNode child : typeNode.down()) {
 			if (child.getKind() != Kind.FIELD) continue;
 			FieldDeclaration fieldDecl = (FieldDeclaration) child.get();
-			//Skip fields that start with $
-			if (fieldDecl.name.length > 0 && fieldDecl.name[0] == '$') continue;
-			//Skip static fields.
-			if ((fieldDecl.modifiers & ClassFileConstants.AccStatic) != 0) continue;
+			if (!EclipseHandlerUtil.filterField(fieldDecl)) continue;
 			boolean isFinal = (fieldDecl.modifiers & ClassFileConstants.AccFinal) != 0;
 			boolean isNonNull = findAnnotations(fieldDecl, TransformationsUtil.NON_NULL_PATTERN).length != 0;
 			if ((isFinal || isNonNull) && fieldDecl.initialization == null) fields.add(child);
@@ -120,6 +119,7 @@ public class HandleConstructor {
 	public static class HandleAllArgsConstructor implements EclipseAnnotationHandler<AllArgsConstructor> {
 		@Override public boolean handle(AnnotationValues<AllArgsConstructor> annotation, Annotation ast, EclipseNode annotationNode) {
 			EclipseNode typeNode = annotationNode.up();
+			if (!checkLegality(typeNode, annotationNode, AllArgsConstructor.class.getSimpleName())) return true;
 			AllArgsConstructor ann = annotation.getInstance();
 			AccessLevel level = ann.access();
 			String staticName = ann.staticName();
@@ -130,12 +130,11 @@ public class HandleConstructor {
 			for (EclipseNode child : typeNode.down()) {
 				if (child.getKind() != Kind.FIELD) continue;
 				FieldDeclaration fieldDecl = (FieldDeclaration) child.get();
-				// Skip fields that start with $
-				if (fieldDecl.name.length > 0 && fieldDecl.name[0] == '$') continue;
-				// Skip static fields.
-				if ((fieldDecl.modifiers & ClassFileConstants.AccStatic) != 0) continue;
+				if (!EclipseHandlerUtil.filterField(fieldDecl)) continue;
+				
 				// Skip initialized final fields.
-				if (((fieldDecl.modifiers & ClassFileConstants.AccFinal) != 0) && fieldDecl.initialization != null) continue;
+				if (((fieldDecl.modifiers & ClassFileConstants.AccFinal) != 0) && fieldDecl.initialization != null) return false;
+				
 				fields.add(child);
 			}
 			new HandleConstructor().generateConstructor(typeNode, level, fields, staticName, false, suppressConstructorProperties, ast);
@@ -143,6 +142,20 @@ public class HandleConstructor {
 		}
 	}
 	
+	static boolean checkLegality(EclipseNode typeNode, EclipseNode errorNode, String name) {
+		TypeDeclaration typeDecl = null;
+		if (typeNode.get() instanceof TypeDeclaration) typeDecl = (TypeDeclaration) typeNode.get();
+		int modifiers = typeDecl == null ? 0 : typeDecl.modifiers;
+		boolean notAClass = (modifiers & (ClassFileConstants.AccInterface | ClassFileConstants.AccAnnotation)) != 0;
+		
+		if (typeDecl == null || notAClass) {
+			errorNode.addError(name + " is only supported on a class or an enum.");
+			return false;
+		}
+		
+		return true;
+	}
+	
 	public void generateRequiredArgsConstructor(EclipseNode typeNode, AccessLevel level, String staticName, boolean skipIfConstructorExists, ASTNode source) {
 		generateConstructor(typeNode, level, findRequiredFields(typeNode), staticName, skipIfConstructorExists, false, source);
 	}
@@ -208,6 +221,10 @@ public class HandleConstructor {
 			EclipseNode type, Collection<EclipseNode> fields, boolean suppressConstructorProperties, ASTNode source) {
 		long p = (long)source.sourceStart << 32 | source.sourceEnd;
 		
+		boolean isEnum = (((TypeDeclaration)type.get()).modifiers & ClassFileConstants.AccEnum) != 0;
+		
+		if (isEnum) level = AccessLevel.PRIVATE;
+		
 		ConstructorDeclaration constructor = new ConstructorDeclaration(
 				((CompilationUnitDeclaration) type.top().get()).compilationResult);
 		Eclipse.setGeneratedBy(constructor, source);

src/core/lombok/eclipse/handlers/HandleEqualsAndHashCode.java

@@ -193,14 +193,12 @@ public class HandleEqualsAndHashCode implements EclipseAnnotationHandler<EqualsA
 			for (EclipseNode child : typeNode.down()) {
 				if (child.getKind() != Kind.FIELD) continue;
 				FieldDeclaration fieldDecl = (FieldDeclaration) child.get();
-				//Skip static fields.
-				if ((fieldDecl.modifiers & ClassFileConstants.AccStatic) != 0) continue;
+				if (!EclipseHandlerUtil.filterField(fieldDecl)) continue;
+				
 				//Skip transient fields.
 				if ((fieldDecl.modifiers & ClassFileConstants.AccTransient) != 0) continue;
 				//Skip excluded fields.
 				if (excludes != null && excludes.contains(new String(fieldDecl.name))) continue;
-				//Skip fields that start with $.
-				if (fieldDecl.name.length > 0 && fieldDecl.name[0] == '$') continue;
 				nodesForEquality.add(child);
 			}
 		}

src/core/lombok/eclipse/handlers/HandleGetter.java

@@ -87,10 +87,10 @@ public class HandleGetter implements EclipseAnnotationHandler<Getter> {
 		if (typeNode.get() instanceof TypeDeclaration) typeDecl = (TypeDeclaration) typeNode.get();
 		int modifiers = typeDecl == null ? 0 : typeDecl.modifiers;
 		boolean notAClass = (modifiers &
-				(ClassFileConstants.AccInterface | ClassFileConstants.AccAnnotation | ClassFileConstants.AccEnum)) != 0;
+				(ClassFileConstants.AccInterface | ClassFileConstants.AccAnnotation)) != 0;
 		
 		if (typeDecl == null || notAClass) {
-			pos.addError("@Getter is only supported on a class or a field.");
+			pos.addError("@Getter is only supported on a class, an enum, or a field.");
 			return false;
 		}
 		
@@ -103,11 +103,7 @@ public class HandleGetter implements EclipseAnnotationHandler<Getter> {
 	public boolean fieldQualifiesForGetterGeneration(EclipseNode field) {
 		if (field.getKind() != Kind.FIELD) return false;
 		FieldDeclaration fieldDecl = (FieldDeclaration) field.get();
-		//Skip fields that start with $
-		if (fieldDecl.name.length > 0 && fieldDecl.name[0] == '$') return false;
-		//Skip static fields.
-		if ((fieldDecl.modifiers & ClassFileConstants.AccStatic) != 0) return false;
-		return true;
+		return EclipseHandlerUtil.filterField(fieldDecl);
 	}
 	
 	/**

src/core/lombok/eclipse/handlers/HandleSetter.java

@@ -85,10 +85,8 @@ public class HandleSetter implements EclipseAnnotationHandler<Setter> {
 		for (EclipseNode field : typeNode.down()) {
 			if (field.getKind() != Kind.FIELD) continue;
 			FieldDeclaration fieldDecl = (FieldDeclaration) field.get();
-			//Skip fields that start with $
-			if (fieldDecl.name.length > 0 && fieldDecl.name[0] == '$') continue;
-			//Skip static fields.
-			if ((fieldDecl.modifiers & ClassFileConstants.AccStatic) != 0) continue;
+			if (!EclipseHandlerUtil.filterField(fieldDecl)) continue;
+			
 			//Skip final fields.
 			if ((fieldDecl.modifiers & ClassFileConstants.AccFinal) != 0) continue;
 			

src/core/lombok/eclipse/handlers/HandleToString.java

@@ -128,10 +128,10 @@ public class HandleToString implements EclipseAnnotationHandler<ToString> {
 		if (typeNode.get() instanceof TypeDeclaration) typeDecl = (TypeDeclaration) typeNode.get();
 		int modifiers = typeDecl == null ? 0 : typeDecl.modifiers;
 		boolean notAClass = (modifiers &
-				(ClassFileConstants.AccInterface | ClassFileConstants.AccAnnotation | ClassFileConstants.AccEnum)) != 0;
+				(ClassFileConstants.AccInterface | ClassFileConstants.AccAnnotation)) != 0;
 		
 		if (typeDecl == null || notAClass) {
-			errorNode.addError("@ToString is only supported on a class.");
+			errorNode.addError("@ToString is only supported on a class or enum.");
 			return false;
 		}
 		
@@ -152,12 +152,11 @@ public class HandleToString implements EclipseAnnotationHandler<ToString> {
 			for (EclipseNode child : typeNode.down()) {
 				if (child.getKind() != Kind.FIELD) continue;
 				FieldDeclaration fieldDecl = (FieldDeclaration) child.get();
-				//Skip static fields.
-				if ((fieldDecl.modifiers & ClassFileConstants.AccStatic) != 0) continue;
+				if (!EclipseHandlerUtil.filterField(fieldDecl)) continue;
+				
 				//Skip excluded fields.
 				if (excludes != null && excludes.contains(new String(fieldDecl.name))) continue;
-				//Skip fields that start with $
-				if (fieldDecl.name.length > 0 && fieldDecl.name[0] == '$') continue;
+				
 				nodesForToString.add(child);
 			}
 		}

src/core/lombok/javac/handlers/HandleConstructor.java

@@ -62,6 +62,7 @@ public class HandleConstructor {
 			markAnnotationAsProcessed(annotationNode, NoArgsConstructor.class);
 			deleteImportFromCompilationUnit(annotationNode, "lombok.AccessLevel");
 			JavacNode typeNode = annotationNode.up();
+			if (!checkLegality(typeNode, annotationNode, NoArgsConstructor.class.getSimpleName())) return true;
 			NoArgsConstructor ann = annotation.getInstance();
 			AccessLevel level = ann.access();
 			String staticName = ann.staticName();
@@ -82,6 +83,7 @@ public class HandleConstructor {
 			markAnnotationAsProcessed(annotationNode, RequiredArgsConstructor.class);
 			deleteImportFromCompilationUnit(annotationNode, "lombok.AccessLevel");
 			JavacNode typeNode = annotationNode.up();
+			if (!checkLegality(typeNode, annotationNode, RequiredArgsConstructor.class.getSimpleName())) return true;
 			RequiredArgsConstructor ann = annotation.getInstance();
 			AccessLevel level = ann.access();
 			String staticName = ann.staticName();
@@ -120,6 +122,7 @@ public class HandleConstructor {
 			markAnnotationAsProcessed(annotationNode, AllArgsConstructor.class);
 			deleteImportFromCompilationUnit(annotationNode, "lombok.AccessLevel");
 			JavacNode typeNode = annotationNode.up();
+			if (!checkLegality(typeNode, annotationNode, AllArgsConstructor.class.getSimpleName())) return true;
 			AllArgsConstructor ann = annotation.getInstance();
 			AccessLevel level = ann.access();
 			String staticName = ann.staticName();
@@ -148,6 +151,20 @@ public class HandleConstructor {
 		}
 	}
 	
+	static boolean checkLegality(JavacNode typeNode, JavacNode errorNode, String name) {
+		JCClassDecl typeDecl = null;
+		if (typeNode.get() instanceof JCClassDecl) typeDecl = (JCClassDecl) typeNode.get();
+		long modifiers = typeDecl == null ? 0 : typeDecl.mods.flags;
+		boolean notAClass = (modifiers & (Flags.INTERFACE | Flags.ANNOTATION)) != 0;
+		
+		if (typeDecl == null || notAClass) {
+			errorNode.addError(name + " is only supported on a class or an enum.");
+			return false;
+		}
+		
+		return true;
+	}
+	
 	public void generateRequiredArgsConstructor(JavacNode typeNode, AccessLevel level, String staticName, boolean skipIfConstructorExists) {
 		generateConstructor(typeNode, level, findRequiredFields(typeNode), staticName, skipIfConstructorExists, false);
 	}

src/core/lombok/javac/handlers/HandleGetter.java

@@ -85,10 +85,10 @@ public class HandleGetter implements JavacAnnotationHandler<Getter> {
 		JCClassDecl typeDecl = null;
 		if (typeNode.get() instanceof JCClassDecl) typeDecl = (JCClassDecl) typeNode.get();
 		long modifiers = typeDecl == null ? 0 : typeDecl.mods.flags;
-		boolean notAClass = (modifiers & (Flags.INTERFACE | Flags.ANNOTATION | Flags.ENUM)) != 0;
+		boolean notAClass = (modifiers & (Flags.INTERFACE | Flags.ANNOTATION)) != 0;
 		
 		if (typeDecl == null || notAClass) {
-			errorNode.addError("@Getter is only supported on a class or a field.");
+			errorNode.addError("@Getter is only supported on a class, an enum, or a field.");
 			return false;
 		}
 		

src/core/lombok/javac/handlers/HandleToString.java

@@ -117,7 +117,7 @@ public class HandleToString implements JavacAnnotationHandler<ToString> {
 		boolean notAClass = true;
 		if (typeNode.get() instanceof JCClassDecl) {
 			long flags = ((JCClassDecl)typeNode.get()).mods.flags;
-			notAClass = (flags & (Flags.INTERFACE | Flags.ANNOTATION | Flags.ENUM)) != 0;
+			notAClass = (flags & (Flags.INTERFACE | Flags.ANNOTATION)) != 0;
 		}
 		
 		if (callSuper == null) {
@@ -127,7 +127,7 @@ public class HandleToString implements JavacAnnotationHandler<ToString> {
 		}
 		
 		if (notAClass) {
-			errorNode.addError("@ToString is only supported on a class.");
+			errorNode.addError("@ToString is only supported on a class or enum.");
 			return false;
 		}
 		

website/features/Constructor.html

@@ -68,6 +68,9 @@
 					The <code>@java.beans.ConstructorProperties</code> annotation is never generated for a constructor with no arguments. This also explains why <code>@NoArgsConstructor</code>
 					lacks the <code>suppressConstructorProperties</code> annotation method. The <code>@ConstructorProperties</code> annotation is also omitted for private constructors. The
 					generated static factory methods also do not get <code>@ConstructorProperties</code>, as this annotation can only be added to real constructors.
+				</p><p>
+					<code>@XArgsConstructor</code> can also be used on an enum definition. The generated constructor will always be
+					private, because non-private constructors aren't legal in enums. You don't have to specify <code>AccessLevel.PRIVATE</code>.
 				</p>
 			</div>
 		</div>

website/features/GetterSetter.html

@@ -67,6 +67,9 @@
 				</p><p>
 				Using the <code>AccessLevel.NONE</code> access level simply generates nothing. It's useful only in combination with
 				<a href="Data.html"><code>@Data</code></a> or a class-wide <code>@Getter</code> or <code>@Setter</code>.
+				</p><p>
+					<code>@Getter</code> can also be used on enums. <code>@Setter</code> can't, not for a technical reason, but
+					for a pragmatic one: Setters on enums are an extremely bad idea.
 				</p>
 			</div>
 		</div>

website/features/ToString.html

@@ -62,6 +62,8 @@
 				</p><p>
 				If a getter exists for a field to be included, it is called instead of using a direct field reference. This behaviour can be suppressed:<br />
 				<code>@ToString(doNotUseGetters = true)</code>
+				</p><p>
+					<code>@ToString</code> can also be used on an enum definition.
 				</p>
 			</div>
 		</div>