[fixes #2046] you can now suppress the builder() method, useful if yo…

…u only want toBuilder(). Also suppresses the warnings about any missing Builder.Default annotations.

doc/changelog.markdown

@@ -3,6 +3,7 @@ Lombok Changelog
 
 ### v1.18.7 "Edgy Guinea Pig"
 * BUGFIX: var/val on methods that return an intersection type would now work in Eclipse [Issue #1986](https://github.com/rzwitserloot/lombok/issues/1986)
+* FEATURE: You can now suppress generation of the `builder` method when using `@Builder`; usually because you're only interested in the `toBuilder` method. As a convenience we won't emit warnings about missing `@Builder.Default` annotations when you do this. [Issue #2046](https://github.com/rzwitserloot/lombok/issues/2046)
 
 ### v1.18.6 (February 12th, 2019)
 * FEATURE: Javadoc on fields will now also be copied to the Builders' setters. Thanks for the contribution, Emil Lundberg. [Issue #2008](https://github.com/rzwitserloot/lombok/issues/2008)

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

@@ -173,7 +173,15 @@ private static final char[] prefixWith(char[] prefix, char[] name) {
 		if (buildMethodName == null) builderMethodName = "build";
 		if (builderClassName == null) builderClassName = "";
 
-		if (!checkName("builderMethodName", builderMethodName, annotationNode)) return;
+		boolean generateBuilderMethod;
+		if (builderMethodName.isEmpty()) {
+			generateBuilderMethod = false;
+		} else if (!checkName("builderMethodName", builderMethodName, annotationNode)) {
+			return;
+		} else {
+			generateBuilderMethod = true;
+		}
+
 		if (!checkName("buildMethodName", buildMethodName, annotationNode)) return;
 		if (!builderClassName.isEmpty()) {
 			if (!checkName("builderClassName", builderClassName, annotationNode)) return;
@@ -192,6 +200,8 @@ private static final char[] prefixWith(char[] prefix, char[] name) {
 		boolean addCleaning = false;
 		boolean isStatic = true;
 
+		List<EclipseNode> nonFinalNonDefaultedFields = null;
+
 		if (parent.get() instanceof TypeDeclaration) {
 			tdParent = parent;
 			TypeDeclaration td = (TypeDeclaration) tdParent.get();
@@ -225,7 +235,8 @@ private static final char[] prefixWith(char[] prefix, char[] name) {
 
 				if (fd.initialization != null && isDefault == null) {
 					if (isFinal) continue;
-					fieldNode.addWarning("@Builder will ignore the initializing expression entirely. If you want the initializing expression to serve as default, add @Builder.Default. If it is not supposed to be settable during building, make the field final.");
+					if (nonFinalNonDefaultedFields == null) nonFinalNonDefaultedFields = new ArrayList<EclipseNode>();
+					nonFinalNonDefaultedFields.add(fieldNode);
 				}
 
 				if (isDefault != null) {
@@ -486,7 +497,8 @@ private static final char[] prefixWith(char[] prefix, char[] name) {
 			if (cleanMethod != null) injectMethod(builderType, cleanMethod);
 		}
 
-		if (methodExists(builderMethodName, tdParent, -1) == MemberExistsResult.NOT_EXISTS) {
+		if (generateBuilderMethod && methodExists(builderMethodName, tdParent, -1) != MemberExistsResult.NOT_EXISTS) generateBuilderMethod = false;
+		if (generateBuilderMethod) {
 			MethodDeclaration md = generateBuilderMethod(isStatic, builderMethodName, builderClassName, tdParent, typeParams, ast);
 			if (md != null) injectMethod(tdParent, md);
 		}
@@ -508,6 +520,12 @@ private static final char[] prefixWith(char[] prefix, char[] name) {
 
 			if (md != null) injectMethod(tdParent, md);
 		}
+
+		if (nonFinalNonDefaultedFields != null && generateBuilderMethod) {
+			for (EclipseNode fieldNode : nonFinalNonDefaultedFields) {
+				fieldNode.addWarning("@Builder will ignore the initializing expression entirely. If you want the initializing expression to serve as default, add @Builder.Default. If it is not supposed to be settable during building, make the field final.");
+			}
+		}
 	}
 
 	private static final char[] BUILDER_TEMP_VAR = {'b', 'u', 'i', 'l', 'd', 'e', 'r'};

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

@@ -119,7 +119,15 @@ static class BuilderFieldData {
 		if (buildMethodName == null) buildMethodName = "build";
 		if (builderClassName == null) builderClassName = "";
 
-		if (!checkName("builderMethodName", builderMethodName, annotationNode)) return;
+		boolean generateBuilderMethod;
+		if (builderMethodName.isEmpty()) {
+			generateBuilderMethod = false;
+		} else if (!checkName("builderMethodName", builderMethodName, annotationNode)) {
+			return;
+		} else {
+			generateBuilderMethod = true;
+		}
+
 		if (!checkName("buildMethodName", buildMethodName, annotationNode)) return;
 		if (!builderClassName.isEmpty()) {
 			if (!checkName("builderClassName", builderClassName, annotationNode)) return;
@@ -140,6 +148,8 @@ static class BuilderFieldData {
 		boolean addCleaning = false;
 		boolean isStatic = true;
 
+		ArrayList<JavacNode> nonFinalNonDefaultedFields = null;
+
 		if (parent.get() instanceof JCClassDecl) {
 			tdParent = parent;
 			JCClassDecl td = (JCClassDecl) tdParent.get();
@@ -172,7 +182,8 @@ static class BuilderFieldData {
 
 				if (fd.init != null && isDefault == null) {
 					if (isFinal) continue;
-					fieldNode.addWarning("@Builder will ignore the initializing expression entirely. If you want the initializing expression to serve as default, add @Builder.Default. If it is not supposed to be settable during building, make the field final.");
+					if (nonFinalNonDefaultedFields == null) nonFinalNonDefaultedFields = new ArrayList<JavacNode>();
+					nonFinalNonDefaultedFields.add(fieldNode);
 				}
 
 				if (isDefault != null) {
@@ -431,7 +442,8 @@ static class BuilderFieldData {
 
 		if (addCleaning) injectMethod(builderType, generateCleanMethod(builderFields, builderType, ast));
 
-		if (methodExists(builderMethodName, tdParent, -1) == MemberExistsResult.NOT_EXISTS) {
+		if (generateBuilderMethod && methodExists(builderMethodName, tdParent, -1) != MemberExistsResult.NOT_EXISTS) generateBuilderMethod = false;
+		if (generateBuilderMethod) {
 			JCMethodDecl md = generateBuilderMethod(isStatic, builderMethodName, builderClassName, annotationNode, tdParent, typeParams);
 			recursiveSetGeneratedBy(md, ast, annotationNode.getContext());
 			if (md != null) injectMethod(tdParent, md);
@@ -459,6 +471,12 @@ static class BuilderFieldData {
 				}
 			}
 		}
+
+		if (nonFinalNonDefaultedFields != null && generateBuilderMethod) {
+			for (JavacNode fieldNode : nonFinalNonDefaultedFields) {
+				fieldNode.addWarning("@Builder will ignore the initializing expression entirely. If you want the initializing expression to serve as default, add @Builder.Default. If it is not supposed to be settable during building, make the field final.");
+			}
+		}
 	}
 
 	private static String unpack(JCExpression expr) {

test/transform/resource/after-delombok/BuilderWithNoBuilderMethod.java

@@ -0,0 +1,33 @@
+class BuilderWithNoBuilderMethod {
+	private String a = "";
+	@java.lang.SuppressWarnings("all")
+	BuilderWithNoBuilderMethod(final String a) {
+		this.a = a;
+	}
+	@java.lang.SuppressWarnings("all")
+	public static class BuilderWithNoBuilderMethodBuilder {
+		@java.lang.SuppressWarnings("all")
+		private String a;
+		@java.lang.SuppressWarnings("all")
+		BuilderWithNoBuilderMethodBuilder() {
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderWithNoBuilderMethodBuilder a(final String a) {
+			this.a = a;
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public BuilderWithNoBuilderMethod build() {
+			return new BuilderWithNoBuilderMethod(a);
+		}
+		@java.lang.Override
+		@java.lang.SuppressWarnings("all")
+		public java.lang.String toString() {
+			return "BuilderWithNoBuilderMethod.BuilderWithNoBuilderMethodBuilder(a=" + this.a + ")";
+		}
+	}
+	@java.lang.SuppressWarnings("all")
+	public BuilderWithNoBuilderMethodBuilder toBuilder() {
+		return new BuilderWithNoBuilderMethodBuilder().a(this.a);
+	}
+}

test/transform/resource/after-ecj/BuilderWithNoBuilderMethod.java

@@ -0,0 +1,27 @@
+import lombok.Builder;
+@Builder(toBuilder = true,builderMethodName = "") class BuilderWithNoBuilderMethod {
+  public static @java.lang.SuppressWarnings("all") class BuilderWithNoBuilderMethodBuilder {
+    private @java.lang.SuppressWarnings("all") String a;
+    @java.lang.SuppressWarnings("all") BuilderWithNoBuilderMethodBuilder() {
+      super();
+    }
+    public @java.lang.SuppressWarnings("all") BuilderWithNoBuilderMethodBuilder a(final String a) {
+      this.a = a;
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") BuilderWithNoBuilderMethod build() {
+      return new BuilderWithNoBuilderMethod(a);
+    }
+    public @java.lang.Override @java.lang.SuppressWarnings("all") java.lang.String toString() {
+      return (("BuilderWithNoBuilderMethod.BuilderWithNoBuilderMethodBuilder(a=" + this.a) + ")");
+    }
+  }
+  private String a = "";
+  @java.lang.SuppressWarnings("all") BuilderWithNoBuilderMethod(final String a) {
+    super();
+    this.a = a;
+  }
+  public @java.lang.SuppressWarnings("all") BuilderWithNoBuilderMethodBuilder toBuilder() {
+    return new BuilderWithNoBuilderMethodBuilder().a(this.a);
+  }
+}

test/transform/resource/before/BuilderWithNoBuilderMethod.java

@@ -0,0 +1,5 @@
+import lombok.Builder;
+@Builder(toBuilder = true, builderMethodName = "")
+class BuilderWithNoBuilderMethod {
+	private String a = "";
+}

test/transform/resource/messages-delombok/BuilderDefaultsWarnings.java.messages

@@ -1,4 +1,4 @@
 13 @Builder.Default requires @Builder on the class for it to mean anything.
-6 @Builder will ignore the initializing expression entirely. If you want the initializing expression to serve as default, add @Builder.Default. If it is not supposed to be settable during building, make the field final.
 8 @Builder.Default requires an initializing expression (' = something;').
 9 @Builder.Default and @Singular cannot be mixed.
+6 @Builder will ignore the initializing expression entirely. If you want the initializing expression to serve as default, add @Builder.Default. If it is not supposed to be settable during building, make the field final.

website/templates/features/Builder.html

@@ -10,6 +10,8 @@
 			<code>@Builder</code> with <code>@Singular</code> adds a clear method since lombok v1.16.8.
 		</p><p>
 			<code>@Builder.Default</code> functionality was added in lombok v1.16.16.
+		</p><p>
+			<code>@Builder(builderMethodName = "")</code> is legal (and will suppress generation of the builder method) starting with lombok v1.18.8.
 		</p>
 	</@f.history>
 
@@ -183,6 +185,13 @@ <h3 id="jackson"><a name="jackson">With Jackson</a></h3>
 			The initializer on a <code>@Builder.Default</code> field is removed and stored in a static method, in order to guarantee that this initializer won't be executed at all if a value is specified in the build. This does mean the initializer cannot refer to <code>this</code>, <code>super</code> or any non-static member. If lombok generates a constructor for you, it'll also initialize this field with the initializer.
 		</p><p>
 			Various well known annotations about nullity cause null checks to be inserted and will be copied to parameter of the builder's 'setter' method. See <a href="/features/GetterSetter">Getter/Setter</a> documentation's small print for more information.
+		</p><p>
+			You can suppress the generation of the <code>builder()</code> method, for example because you <em>just</em> want the <code>toBuilder()</code> functionality, by using:
+			<code>@Builder(builderMethodName = "")</code>. Any warnings about missing <code>@Builder.Default</code> annotations will disappear when you do this, as such warnings
+			are not relevant when only using <code>toBuilder()</code> to make builder instances.
+		</p><p>
+			You can use <code>@Builder</code> for copy constructors: <code>foo.toBuilder().build()</code> makes a shallow clone. Consider suppressing the generating of the
+			<code>builder</code> method if you just want this functionality, by using: <code>@Builder(toBuilder = true, builderMethodName = "")</code>.
 		</p><p>
 			Due to a peculiar way javac processes static imports, trying to do a non-star static import of the static <code>builder()</code> method won't work. Either use a star static import: `import static TypeThatHasABuilder.*;` or don't statically import the <code>builder</code> method.
 		</p>