support for @Builder on methods with a generified return type. Fixes #1420

doc/changelog.markdown

@@ -10,6 +10,7 @@ Lombok Changelog
 * BUGFIX: The generated hashCode would break the contract if `callSuper=true,of={}`. [Issue #1505](https://github.com/rzwitserloot/lombok/issues/1505)
 * BUGFIX: `delombok` no longer prints the synthetic outer-class parameter. [Issue #1521](https://github.com/rzwitserloot/lombok/issues/1521)
 * BUGFIX: @Builder.Default now also works when type parameters are present. [Issue #1527](https://github.com/rzwitserloot/lombok/issues/1527)
+* BUGFIX: @Builder now also works on method with a generified return type. [Issue #1420](https://github.com/rzwitserloot/lombok/issues/1420)
 * INSTALLER: By default, the lombok installer now inserts an absolute path in `eclipse.ini` and friends, instead of a relative path. If you want the old behavior, you can use `java -jar -Dlombok.installer.fullpath=false lombok.jar`.
 
 ### v1.16.18 (July 3rd, 2017)

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

@@ -212,7 +212,7 @@ public class HandleBuilder extends JavacAnnotationHandler<Builder> {
 			thrownExceptions = jmd.thrown;
 			nameOfBuilderMethod = jmd.name;
 			if (returnType instanceof JCTypeApply) {
-				returnType = ((JCTypeApply) returnType).clazz;
+				returnType = cloneType(tdParent.getTreeMaker(), returnType, ast, annotationNode.getContext());
 			}
 			if (builderClassName.isEmpty()) {
 				if (returnType instanceof JCFieldAccess) {
@@ -232,7 +232,16 @@ public class HandleBuilder extends JavacAnnotationHandler<Builder> {
 					if (Character.isLowerCase(builderClassName.charAt(0))) {
 						builderClassName = Character.toTitleCase(builderClassName.charAt(0)) + builderClassName.substring(1);
 					}
-				} else {
+				} else if (returnType instanceof JCTypeApply) {
+					JCExpression clazz = ((JCTypeApply) returnType).clazz;
+					if (clazz instanceof JCFieldAccess) {
+						builderClassName = ((JCFieldAccess) clazz).name + "Builder";
+					} else if (clazz instanceof JCIdent) {
+						builderClassName = ((JCIdent) clazz).name + "Builder";
+					}
+				}
+				
+				if (builderClassName.isEmpty()) {
 					// This shouldn't happen.
 					System.err.println("Lombok bug ID#20140614-1651: javac HandleBuilder: return type to name conversion failed: " + returnType.getClass());
 					builderClassName = td.name.toString() + "Builder";
@@ -253,11 +262,14 @@ public class HandleBuilder extends JavacAnnotationHandler<Builder> {
 					tpOnRet = ((JCTypeApply) fullReturnType).arguments;
 				}
 				
-				if (returnType instanceof JCIdent) {
-					simpleName = ((JCIdent) returnType).name;
+				JCExpression namingType = returnType;
+				if (returnType instanceof JCTypeApply) namingType = ((JCTypeApply) returnType).clazz;
+				
+				if (namingType instanceof JCIdent) {
+					simpleName = ((JCIdent) namingType).name;
 					pkg = null;
-				} else if (returnType instanceof JCFieldAccess) {
-					JCFieldAccess jcfa = (JCFieldAccess) returnType;
+				} else if (namingType instanceof JCFieldAccess) {
+					JCFieldAccess jcfa = (JCFieldAccess) namingType;
 					simpleName = jcfa.name;
 					pkg = unpack(jcfa.selected);
 					if (pkg.startsWith("ERR:")) {
@@ -266,7 +278,7 @@ public class HandleBuilder extends JavacAnnotationHandler<Builder> {
 						return;
 					}
 				} else {
-					annotationNode.addError("Expected a (parameterized) type here instead of a " + returnType.getClass().getName());
+					annotationNode.addError("Expected a (parameterized) type here instead of a " + namingType.getClass().getName());
 					return;
 				}
 				

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

@@ -0,0 +1,40 @@
+import java.util.List;
+import java.util.*;
+class BuilderGenericMethod<T> {
+	public <N extends Number> Map<N, T> foo(int a, long b) {
+		return null;
+	}
+	@java.lang.SuppressWarnings("all")
+	public class MapBuilder<N extends Number> {
+		@java.lang.SuppressWarnings("all")
+		private int a;
+		@java.lang.SuppressWarnings("all")
+		private long b;
+		@java.lang.SuppressWarnings("all")
+		MapBuilder() {
+		}
+		@java.lang.SuppressWarnings("all")
+		public MapBuilder<N> a(final int a) {
+			this.a = a;
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public MapBuilder<N> b(final long b) {
+			this.b = b;
+			return this;
+		}
+		@java.lang.SuppressWarnings("all")
+		public Map<N, T> build() {
+			return BuilderGenericMethod.this.<N>foo(a, b);
+		}
+		@java.lang.Override
+		@java.lang.SuppressWarnings("all")
+		public java.lang.String toString() {
+			return "BuilderGenericMethod.MapBuilder(a=" + this.a + ", b=" + this.b + ")";
+		}
+	}
+	@java.lang.SuppressWarnings("all")
+	public <N extends Number> MapBuilder<N> builder() {
+		return new MapBuilder<N>();
+	}
+}

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

@@ -24,7 +24,7 @@ class BuilderWithExistingBuilderClass<T, K extends Number> {
 			return this;
 		}
 		@java.lang.SuppressWarnings("all")
-		public BuilderWithExistingBuilderClass build() {
+		public BuilderWithExistingBuilderClass<String, Z> build() {
 			return BuilderWithExistingBuilderClass.<Z>staticMethod(arg1, arg2, arg3);
 		}
 		@java.lang.Override

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

@@ -165,7 +165,7 @@ class StaticWithToBuilder<T, K> {
 			return this;
 		}
 		@java.lang.SuppressWarnings("all")
-		public StaticWithToBuilder build() {
+		public StaticWithToBuilder<Z, String> build() {
 			return StaticWithToBuilder.<Z>test(mOne, bar);
 		}
 		@java.lang.Override

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

@@ -0,0 +1,35 @@
+import java.util.List;
+import lombok.Builder;
+import java.util.*;
+class BuilderGenericMethod<T> {
+  public @java.lang.SuppressWarnings("all") class MapBuilder<N extends Number> {
+    private @java.lang.SuppressWarnings("all") int a;
+    private @java.lang.SuppressWarnings("all") long b;
+    @java.lang.SuppressWarnings("all") MapBuilder() {
+      super();
+    }
+    public @java.lang.SuppressWarnings("all") MapBuilder<N> a(final int a) {
+      this.a = a;
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") MapBuilder<N> b(final long b) {
+      this.b = b;
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") Map<N, T> build() {
+      return BuilderGenericMethod.this.<N>foo(a, b);
+    }
+    public @java.lang.Override @java.lang.SuppressWarnings("all") java.lang.String toString() {
+      return (((("BuilderGenericMethod.MapBuilder(a=" + this.a) + ", b=") + this.b) + ")");
+    }
+  }
+  BuilderGenericMethod() {
+    super();
+  }
+  public @Builder <N extends Number>Map<N, T> foo(int a, long b) {
+    return null;
+  }
+  public @java.lang.SuppressWarnings("all") <N extends Number>MapBuilder<N> builder() {
+    return new MapBuilder<N>();
+  }
+}

test/transform/resource/before/BuilderGenericMethod.java

@@ -0,0 +1,11 @@
+import java.util.List;
+
+import lombok.Builder;
+import java.util.*;
+
+class BuilderGenericMethod<T> {
+	@Builder
+	public <N extends Number> Map<N,T> foo(int a, long b) {
+		return null;
+	}
+}