Merge pull request #295 from scala/topic/java-fields

(wip) stop compiling when pickler fields are empty. Fixes #60, #263

build.sbt

@@ -51,6 +51,7 @@ lazy val root: Project = (project in file(".")).
 
 /** Scala Pickling code */
 lazy val core: Project = (project in file("core")).
+  dependsOn(testUtil % "test->test").
   settings(commonSettings: _*).
   settings(
     name := "scala-pickling",
@@ -73,6 +74,9 @@ lazy val core: Project = (project in file("core")).
     }
   )
 
+lazy val testUtil: Project = (project in file("test-util")).
+  settings(commonSettings ++ noPublish: _*)
+
 lazy val sandbox: Project = (project in file("sandbox")).
   dependsOn(core).
   settings(commonSettings ++ noPublish: _*).

core/src/main/scala/pickling/Macros.scala

@@ -7,6 +7,9 @@ import ir._
 trait TypeAnalysis extends Macro {
   import c.universe._
 
+  def isStaticOnly: Boolean =
+    c.inferImplicitValue(typeOf[IsStaticOnly]) != EmptyTree
+
   def isCaseClass(sym: TypeSymbol): Boolean =
     sym.isClass && sym.asClass.isCaseClass
 
@@ -188,7 +191,8 @@ trait PicklerMacros extends Macro with PickleMacros with FastTypeTagMacros {
               scala.pickling.PickleOps(out).pickleInto(b)
             )
           """)
-        } else (nonLoopyFields ++ loopyFields).flatMap(fir => {
+        }
+        else (nonLoopyFields ++ loopyFields).flatMap(fir => {
         // for each field, compute a tree for pickling it
         // (or empty list, if impossible)
 
@@ -225,11 +229,16 @@ trait PicklerMacros extends Macro with PickleMacros with FastTypeTagMacros {
           else reflectively("picklee", fir)(fm => putField(q"$fm.get.asInstanceOf[${fir.tpe}]"))
         } else if (fir.javaSetter.isDefined) {
           List(putField(getField(fir)))
+        } else if (!fir.isParam && sym.isJava) {
+          Nil
         } else {
           reflectivelyWithoutGetter("picklee", fir)(fvalue =>
             tryPutField(q"$fvalue.asInstanceOf[scala.util.Try[${fir.tpe}]]"))
         }
       })
+      if (cir.fields.nonEmpty && putFields.isEmpty) {
+        throw PicklingException("No fields are captured. You need a custom pickler to handle this.")
+      }
       val endEntry = q"builder.endEntry()"
       if (shouldBotherAboutSharing(tpe)) {
         q"""
@@ -298,7 +307,7 @@ trait PicklerMacros extends Macro with PickleMacros with FastTypeTagMacros {
 
       case tpe1 if sym.isClass =>
         def pickleAfterDispatch(excludeSelf: Boolean) = {
-          val dispatchTree = if (c.inferImplicitValue(typeOf[IsStaticOnly]) != EmptyTree) { // StaticOnly *imported*
+          val dispatchTree = if (isStaticOnly) { // StaticOnly *imported*
             val notClosedReasons = whyNotClosed(sym.asType)
             if (notClosedReasons.nonEmpty)
               c.abort(c.enclosingPosition, s"cannot generate fully static pickler because: ${notClosedReasons.mkString(", ")}")

core/src/test/scala/pickling/NegativeCompilation.scala

@@ -61,9 +61,12 @@ object NegativeCompilation {
   }
 
   def toolboxClasspath = {
-    val f = new java.io.File(s"core/target/scala-${scalaBinaryVersion}/classes")
-    if (!f.exists) sys.error(s"output directory ${f.getAbsolutePath} does not exist.")
-    f.getAbsolutePath
+    val f0 = new java.io.File(s"core/target/scala-${scalaBinaryVersion}/classes")
+    val f1 = new java.io.File(s"test-util/target/scala-${scalaBinaryVersion}/test-classes")
+    val fs = Vector(f0, f1)
+    fs foreach { f => if (!f.exists) sys.error(s"output directory ${f.getAbsolutePath} does not exist.") }
+    val sep = sys.props("file.separator")
+    fs.map(_.getAbsolutePath).mkString(sep)
   }
 
   def quasiquotesJar: String = {

core/src/test/scala/pickling/neg/java-field-fail.scala

@@ -0,0 +1,20 @@
+package scala.pickling.javafieldfail
+
+import scala.pickling._
+import NegativeCompilation._
+import org.scalatest.FunSuite
+
+class JavaFieldFailTest extends FunSuite {
+  test("x.pickle does not compile for FakeByte") {
+    expectError("Cannot generate") {
+      """import _root_.scala.pickling._
+        |import _root_.scala.pickling.Defaults._
+        |import _root_.scala.pickling.json._
+        |import _root_.scala.pickling.static._
+        |import scala.pickling.javafieldfail.FakeByte
+        |
+        |val x: FakeByte = new FakeByte(10)
+        |val pkl = x.pickle""".stripMargin
+    }
+  }
+}

test-util/src/test/java/pickling/FakeByte.java

@@ -0,0 +1,14 @@
+package scala.pickling.javafieldfail;
+
+public final class FakeByte {
+    private static final long serialVersionUID = 1L;
+    private final byte value;
+
+    public FakeByte(byte value) {
+        this.value = value;
+    }
+
+    public byte byteValue() {
+        return value;
+    }
+}