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lambda's in files on bootclasspath #21

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johanvos opened this issue Jun 4, 2014 · 4 comments
Closed

lambda's in files on bootclasspath #21

johanvos opened this issue Jun 4, 2014 · 4 comments

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@johanvos
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johanvos commented Jun 4, 2014

First of all, thanks for this great project.
I'm trying to apply retrolambda to the OpenJFX codebase containing the JavaFX classes. Currently, the Android port of OpenJFX uses a backported version of the JavaFX sources, and we're now trying to build everything from the latest OpenJFX sources.
The issue I have is that the JavaFX files we try to de-lambdafy are also in the boot classpath (they are in jre/lib/ext/jfxrt.jar). If I remove jfxrt.jar from the Java 8 SDK, the retrolambda process works fine.

However, when jfxrt.jar is present, there are issues since the JavaFX class files can be loaded by 2 classloaders (system classloader and the classloader scanning the retrolambda.inputDir). I tried to bypass this by prepending the bootclasspath with the javafx classes we want to process, e.g.:
java -Xbootclasspath/p:in -Dretrolambda.inputDir=in -Dretrolambda.outputDir=out -Dretrolambda.classpath=in -javaagent:retrolambda.jar -jar retrolambda.jar

But that doesn't work since the classes are then ignored, since LambdaSavingClassFileTransformer.transform() will skip classes on the System classloader

More info on this issue is available at
http://mail.openjdk.java.net/pipermail/openjfx-dev/2014-June/014217.html
@luontola
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luontola commented Jun 4, 2014

Hmm. Some options come to my mind:

  1. Use some include/exclude patterns for defining the packages from which lambdas are backported.
    • Requires extra configuration from users, which is not desirable.
  2. Make it so that all classloaders are equal, and Retrolambda will check from the file system whether the class came from the input directory.
    • Lambda classes do not exists as files, so it would have to detect the enclosing class based on the class name.
  3. LambdaReifier#reifyLambdaClass could communicate to the LambdaSavingClassFileTransformer that this is a lambda class that we want to save.
  • Should work and be reliable.

I'm leaning towards option 3.

@johanvos
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johanvos commented Jun 6, 2014

I agree with your remarks. Option 3 is probably the best one. For now, I'm removing the jfxrt.jar from the SDK in order to use retrolambda on the JavaFX classes in OpenJFX and that works fine, so there is no pressure for this issue ;)

Thanks.

@luontola
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luontola commented Jul 4, 2014

This has been included in Retrolambda 1.4.0

@luontola
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luontola commented Jul 4, 2014

Please try if version 1.4.0 works for your use case - I didn't test it.

Arneball added a commit to Arneball/retrolambda that referenced this issue Aug 11, 2014
@Arneball
package testpackage;
8e13c80 
public interface MyInterface {
    default String def() {
        return "[" + toString() + ", " + "def]";
    }

    default String join(MyInterface other) {
        return def() + other.def();
    }
}

class C implements MyInterface{}  compiles to:

public class testpackage.MyClass implements testpackage.MyInterface {
  public testpackage.MyClass();
    Code:
       0: aload_0
       1: invokespecial luontola#16                 // Method java/lang/Object."<init>":()V
       4: return

  public java.lang.String join(testpackage.MyInterface);
    Code:
       0: aload_0
       1: aload_1
       2: invokestatic  luontola#46                 // Method testpackage/MyInterfacehelper.join:(Ltestpackage/MyInterface;Ltestpackage/MyInterface;)Ljava/lang/String;
       5: areturn

  public java.lang.String def();
    Code:
       0: aload_0
       1: invokestatic  luontola#49                 // Method testpackage/MyInterfacehelper.def:(Ltestpackage/MyInterface;)Ljava/lang/String;
       4: areturn
}

Where testpackage.MyInterfacehelper is compiled to
public class testpackage.MyInterfacehelper {
  private testpackage.MyInterfacehelper();
    Code:
       0: aload_0
       1: invokespecial luontola#9                  // Method java/lang/Object."<init>":()V
       4: return

  public static java.lang.String def(testpackage.MyInterface);
    Code:
       0: new           luontola#13                 // class java/lang/StringBuilder
       3: dup
       4: invokespecial luontola#14                 // Method java/lang/StringBuilder."<init>":()V
       7: ldc           luontola#16                 // String [
       9: invokevirtual luontola#20                 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      12: aload_0
      13: invokevirtual luontola#24                 // Method java/lang/Object.toString:()Ljava/lang/String;
      16: invokevirtual luontola#20                 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      19: ldc           luontola#26                 // String ,
      21: invokevirtual luontola#20                 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      24: ldc           luontola#28                 // String def]
      26: invokevirtual luontola#20                 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      29: invokevirtual luontola#29                 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
      32: areturn

  public static java.lang.String join(testpackage.MyInterface, testpackage.MyInterface);
    Code:
       0: new           luontola#13                 // class java/lang/StringBuilder
       3: dup
       4: invokespecial luontola#14                 // Method java/lang/StringBuilder."<init>":()V
       7: aload_0
       8: invokeinterface luontola#35,  1           // InterfaceMethod testpackage/MyInterface.def:()Ljava/lang/String;
      13: invokevirtual luontola#20                 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      16: aload_1
      17: invokeinterface luontola#35,  1           // InterfaceMethod testpackage/MyInterface.def:()Ljava/lang/String;
      22: invokevirtual luontola#20                 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      25: invokevirtual luontola#29                 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
      28: areturn
}

==============
interface StaticTest {
    static <T> T staticMethod(T t) {
        return t;
    }
}
compiles to
public class testpackage.StaticTesthelper {
  private testpackage.StaticTesthelper();
    Code:
       0: aload_0
       1: invokespecial luontola#9                  // Method java/lang/Object."<init>":()V
       4: return

  public static <T> T staticMethod$static(T);
    Code:
       0: aload_0
       1: areturn
}

========

Brigde methods are generated properly in example:
public interface BridgeParent<T> {
    T get();
}
public interface StringBridges extends BridgeParent<String> {
    @OverRide
    default String get() {
        return "default method";
    }

    default String concrete() {
        return "concrete";
    }
}
public class testpackage.StringBridgeshelper
  SourceFile: "testpackage/StringBridges.java"
  minor version: 0
  major version: 50
  flags: ACC_PUBLIC, ACC_SUPER
Constant pool:
   luontola#1 = Utf8               testpackage/StringBridgeshelper
   luontola#2 = Class              luontola#1             //  testpackage/StringBridgeshelper
   luontola#3 = Utf8               java/lang/Object
   luontola#4 = Class              luontola#3             //  java/lang/Object
   luontola#5 = Utf8               testpackage/StringBridges.java
   luontola#6 = Utf8               <init>
   luontola#7 = Utf8               ()V
   luontola#8 = NameAndType        luontola#6:luontola#7          //  "<init>":()V
   luontola#9 = Methodref          luontola#4.luontola#8          //  java/lang/Object."<init>":()V
  luontola#10 = Utf8               get
  luontola#11 = Utf8               (Ltestpackage/StringBridges;)Ljava/lang/String;
  luontola#12 = Utf8               default method
  luontola#13 = String             luontola#12            //  default method
  luontola#14 = Utf8               concrete
  luontola#15 = String             luontola#14            //  concrete
  luontola#16 = Utf8               (Ltestpackage/StringBridges;)Ljava/lang/Object;
  luontola#17 = Utf8               testpackage/StringBridges
  luontola#18 = Class              luontola#17            //  testpackage/StringBridges
  luontola#19 = Utf8               ()Ljava/lang/String;
  luontola#20 = NameAndType        luontola#10:luontola#19        //  get:()Ljava/lang/String;
  luontola#21 = InterfaceMethodref luontola#18.luontola#20        //  testpackage/StringBridges.get:()Ljava/lang/String;
  luontola#22 = Utf8               Code
  luontola#23 = Utf8               LineNumberTable
  luontola#24 = Utf8               SourceFile
{
  private testpackage.StringBridgeshelper();
    descriptor: ()V
    flags: ACC_PRIVATE
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: invokespecial luontola#9                  // Method java/lang/Object."<init>":()V
         4: return

  public static java.lang.String get(testpackage.StringBridges);
    descriptor: (Ltestpackage/StringBridges;)Ljava/lang/String;
    flags: ACC_PUBLIC, ACC_STATIC
    Code:
      stack=1, locals=1, args_size=1
         0: ldc           luontola#13                 // String default method
         2: areturn
      LineNumberTable:
        line 9: 0

  public static java.lang.String concrete(testpackage.StringBridges);
    descriptor: (Ltestpackage/StringBridges;)Ljava/lang/String;
    flags: ACC_PUBLIC, ACC_STATIC
    Code:
      stack=1, locals=1, args_size=1
         0: ldc           luontola#15                 // String concrete
         2: areturn
      LineNumberTable:
        line 13: 0

  public static java.lang.Object get(testpackage.StringBridges);
    descriptor: (Ltestpackage/StringBridges;)Ljava/lang/Object;
    flags: ACC_PUBLIC, ACC_STATIC, ACC_BRIDGE, ACC_SYNTHETIC
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: invokeinterface luontola#21,  1           // InterfaceMethod testpackage/StringBridges.get:()Ljava/lang/String;
         6: areturn
      LineNumberTable:
        line 6: 0
}
@Arneball Arneball mentioned this issue Aug 11, 2014
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@luontola @johanvos