Reification of classes now produces trees that can be compiled and run. #24

xeno-by · 2011-12-04T20:15:49Z

Multiple minor fixes to Martin's implementation of reflection infrastructure.
Dominating theme is allowing for the fact that compilation via reflection
involves numerous exports/imports between various reflection universes.

Fixes SI-5230. Review by @odersky.

@odersky

Multiple minor fixes to Martin's implementation of reflection infrastructure. Dominating theme is allowing for the fact that compilation via reflection involves numerous exports/imports between various reflection universes. Fixes SI-5230. Review by @odersky.

Build scala library for gwt with continuations enabled.

``` cat sandbox/test.scala && qscalac -target:jvm-1.8 -Ybackend:GenASM sandbox/test.scala && (for c in 'T' 'T$' 'C'; do javap -c -classpath . $c; done) | cat -v; qscala Test trait T { def t(s: String) = 42 val v = 42 } class C extends T object Test { def main(args: Array[String]): Unit = { println(new C().t("")) } } Compiled from "test.scala" public interface T { public abstract void T$_setter_$v_$eq(int); public int t(java.lang.String); Code: 0: bipush 42 2: ireturn public abstract int v(); } Error: class not found: T$ Compiled from "test.scala" public class C implements T { public int v(); Code: 0: aload_0 1: getfield #15 // Field v:I 4: ireturn public void T$_setter_$v_$eq(int); Code: 0: aload_0 1: iload_1 2: putfield #15 // Field v:I 5: return public C(); Code: 0: aload_0 1: invokespecial #24 // Method java/lang/Object."<init>":()V 4: aload_0 5: invokestatic #30 // Method T$class.$init$:(LT;)V 8: return } 42 topic/indylambda-emit-indy /code/scala2 cat sandbox/test.scala && qscalac -target:jvm-1.8 -Ybackend:GenBCode sandbox/test.scala && (for c in 'T' 'T$' 'C'; do javap -c -classpath . $c; done) | cat -v; qscala Test trait T { def t(s: String) = 42 val v = 42 } class C extends T object Test { def main(args: Array[String]): Unit = { println(new C().t("")) } } Compiled from "test.scala" public interface T { public abstract void T$_setter_$v_$eq(int); public int t(java.lang.String); Code: 0: bipush 42 2: ireturn public abstract int v(); } Error: class not found: T$ Compiled from "test.scala" public class C implements T { public int v(); Code: 0: aload_0 1: getfield #15 // Field v:I 4: ireturn public void T$_setter_$v_$eq(int); Code: 0: aload_0 1: iload_1 2: putfield #15 // Field v:I 5: return public C(); Code: 0: aload_0 1: invokespecial #24 // Method java/lang/Object."<init>":()V 4: aload_0 5: invokestatic #30 // Method T$class.$init$:(LT;)V 8: return } 42 ```

And do the same for the specialized variants. Tested by a Java source file that uses lambda syntax to create instances of generic and specialized `Function{0,1}`. Here's how the interfaces look now: ``` % javap -c -classpath /tmp/function 'scala.Function1' Compiled from "Function1.scala" public interface scala.Function1<T1, R> { public abstract R apply(T1); public <A> scala.Function1<A, R> compose(scala.Function1<A, T1>); Code: 0: aload_0 1: aload_1 2: invokestatic #18 // Method scala/Function1$class.compose:(Lscala/Function1;Lscala/Function1;)Lscala/Function1; 5: areturn public <A> scala.Function1<T1, A> andThen(scala.Function1<R, A>); Code: 0: aload_0 1: aload_1 2: invokestatic #24 // Method scala/Function1$class.andThen:(Lscala/Function1;Lscala/Function1;)Lscala/Function1; 5: areturn public abstract java.lang.String toString(); public int apply$mcII$sp(int); Code: 0: aload_0 1: iload_1 2: invokestatic #110 // Method scala/Function1$class.apply$mcII$sp:(Lscala/Function1;I)I 5: ireturn public long apply$mcJI$sp(int); Code: 0: aload_0 1: iload_1 2: invokestatic #115 // Method scala/Function1$class.apply$mcJI$sp:(Lscala/Function1;I)J 5: lreturn ... } % javap -c -classpath /tmp/function 'scala.Function1$mcII$sp' Compiled from "Function1.scala" public interface scala.Function1$mcII$sp extends scala.Function1<java.lang.Object, java.lang.Object> { public java.lang.Object apply(java.lang.Object); Code: 0: aload_0 1: aload_1 2: invokestatic #16 // Method scala/runtime/BoxesRunTime.unboxToInt:(Ljava/lang/Object;)I 5: invokeinterface #19, 2 // InterfaceMethod apply:(I)I 10: invokestatic #23 // Method scala/runtime/BoxesRunTime.boxToInteger:(I)Ljava/lang/Integer; 13: areturn public abstract int apply$mcII$sp(int); public int apply(int); Code: 0: aload_0 1: iload_1 2: invokeinterface #30, 2 // InterfaceMethod apply$mcII$sp:(I)I 7: ireturn } ```

And do the same for the specialized variants. Tested by a Java source file that uses lambda syntax to create instances of generic and specialized `Function{0,1}`. Here's how the interfaces look now: ``` % javap -c -classpath /tmp/function 'scala.Function1' Compiled from "Function1.scala" public interface scala.Function1<T1, R> { public abstract R apply(T1); public <A> scala.Function1<A, R> compose(scala.Function1<A, T1>); Code: 0: aload_0 1: aload_1 2: invokestatic #18 // Method scala/Function1$class.compose:(Lscala/Function1;Lscala/Function1;)Lscala/Function1; 5: areturn public <A> scala.Function1<T1, A> andThen(scala.Function1<R, A>); Code: 0: aload_0 1: aload_1 2: invokestatic #24 // Method scala/Function1$class.andThen:(Lscala/Function1;Lscala/Function1;)Lscala/Function1; 5: areturn public abstract java.lang.String toString(); public int apply$mcII$sp(int); Code: 0: aload_0 1: iload_1 2: invokestatic scala#110 // Method scala/Function1$class.apply$mcII$sp:(Lscala/Function1;I)I 5: ireturn public long apply$mcJI$sp(int); Code: 0: aload_0 1: iload_1 2: invokestatic scala#115 // Method scala/Function1$class.apply$mcJI$sp:(Lscala/Function1;I)J 5: lreturn ... } % javap -c -classpath /tmp/function 'scala.Function1$mcII$sp' Compiled from "Function1.scala" public interface scala.Function1$mcII$sp extends scala.Function1<java.lang.Object, java.lang.Object> { public java.lang.Object apply(java.lang.Object); Code: 0: aload_0 1: aload_1 2: invokestatic #16 // Method scala/runtime/BoxesRunTime.unboxToInt:(Ljava/lang/Object;)I 5: invokeinterface #19, 2 // InterfaceMethod apply:(I)I 10: invokestatic #23 // Method scala/runtime/BoxesRunTime.boxToInteger:(I)Ljava/lang/Integer; 13: areturn public abstract int apply$mcII$sp(int); public int apply(int); Code: 0: aload_0 1: iload_1 2: invokeinterface scala#30, 2 // InterfaceMethod apply$mcII$sp:(I)I 7: ireturn } ```

fix regression in handling of Java-defined classes

``` ⚡ cat sandbox/test.scala trait T { def m = v val v = 42 } class C extends T object Test { def main(args: Array[String]): Unit = { assert(new C().m == 42) } } /code/scala on topic/nuke-impl-classes* ⚡ qscalac -Xprint:fields,constructors,erasure,mixin sandbox/test.scala && qscala Test [[syntax trees at end of fields]] // test.scala package <empty> { abstract <sub_synth> trait T extends scala.AnyRef { <accessor> <sub_synth> def T$_setter_$v_=(x$1: Int): Unit; def /*T*/$init$(): Unit = { () }; def m: Int = T.this.v; <stable> <accessor> <sub_synth> def v: Int = 42 }; <sub_synth> class C extends AnyRef with T { override <stable> <accessor> def v: Int = C.this.v; private[this] val v: Int = _; override <accessor> def T$_setter_$v_=(x$1: Int): Unit = C.this.v = x$1; def <init>(): C = { C.super.<init>(); () } }; object Test extends scala.AnyRef { def <init>(): Test.type = { Test.super.<init>(); () }; def main(args: Array[String]): Unit = scala.Predef.assert(new C().m.==(42)) } } [[syntax trees at end of erasure]] // test.scala package <empty> { abstract <sub_synth> trait T extends Object { <accessor> <defaultmethod> <sub_synth> def T$_setter_$v_=(x$1: Int): Unit; def /*T*/$init$(): Unit = { () }; <defaultmethod> def m(): Int = T.this.v(); <stable> <accessor> <defaultmethod> <sub_synth> def v(): Int = 42 }; <sub_synth> class C extends Object with T { override <stable> <accessor> def v(): Int = C.this.v; private[this] val v: Int = _; override <accessor> def T$_setter_$v_=(x$1: Int): Unit = C.this.v = x$1; def <init>(): C = { C.super.<init>(); C.super./*T*/$init$(); () } }; <sub_synth> object Test extends Object { def <init>(): Test.type = { Test.super.<init>(); () }; def main(args: Array[String]): Unit = scala.Predef.assert(new C().m().==(42)) } } [[syntax trees at end of constructors]] // test.scala package <empty> { abstract <sub_synth> trait T extends Object { <accessor> <defaultmethod> <sub_synth> def T$_setter_$v_=(x$1: Int): Unit; <defaultmethod> def m(): Int = T.this.v(); <stable> <accessor> <defaultmethod> <sub_synth> def v(): Int; def /*T*/$init$(): Unit = { T.this.T$_setter_$v_=(42); () } }; <sub_synth> class C extends Object with T { override <stable> <accessor> def v(): Int = C.this.v; private[this] val v: Int = _; override <accessor> def T$_setter_$v_=(x$1: Int): Unit = C.this.v = x$1; def <init>(): C = { C.super.<init>(); C.super./*T*/$init$(); () } }; <sub_synth> object Test extends Object { def main(args: Array[String]): Unit = scala.Predef.assert(new C().m().==(42)); def <init>(): Test.type = { Test.super.<init>(); () } } } [[syntax trees at end of mixin]] // test.scala: tree is unchanged since constructors /code/scala on topic/nuke-impl-classes* ⚡ javap -c -classpath . T C Compiled from "test.scala" public interface T { public abstract void T$_setter_$v_$eq(int); public int m(); Code: 0: aload_0 1: invokeinterface #15, 1 // InterfaceMethod v:()I 6: ireturn public abstract int v(); public void $init$(); Code: 0: aload_0 1: bipush 42 3: invokeinterface #21, 2 // InterfaceMethod T$_setter_$v_$eq:(I)V 8: return } Compiled from "test.scala" public class C implements T { public int v(); Code: 0: aload_0 1: getfield #15 // Field v:I 4: ireturn public void T$_setter_$v_$eq(int); Code: 0: aload_0 1: iload_1 2: putfield #15 // Field v:I 5: return public C(); Code: 0: aload_0 1: invokespecial #24 // Method java/lang/Object."<init>":()V 4: aload_0 5: invokespecial #27 // Method T.$init$:()V 8: return } ```

And use this as the target of the default methods or statically resolved super or $init calls. The call-site change is predicated on `-Yuse-trait-statics` as a stepping stone for experimentation / bootstrapping. I have performed this transformation in the backend, rather than trying to reflect this in the view from Scala symbols + ASTs. ``` > ;scalac sandbox/test.scala ; scala Test [info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test T C [success] Total time: 2 s, completed 04/05/2016 11:07:13 AM > eval "javap -classpath . -c -private C".!! [info] ans: String = Compiled from "test.scala" [info] public class C implements T { [info] public C(); [info] Code: [info] 0: aload_0 [info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V [info] 4: aload_0 [info] 5: invokespecial #17 // Method T.$init$:()V [info] 8: getstatic #23 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 11: ldc #24 // String C [info] 13: invokevirtual #28 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 16: aload_0 [info] 17: invokespecial #32 // Method T.foo:()I [info] 20: pop [info] 21: return [info] } > ;scalac -Yuse-trait-statics sandbox/test.scala ; scala Test [info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test T C [success] Total time: 2 s, completed 04/05/2016 11:07:39 AM > eval "javap -classpath . -c -private C".!! [info] ans: String = Compiled from "test.scala" [info] public class C implements T { [info] public C(); [info] Code: [info] 0: aload_0 [info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V [info] 4: aload_0 [info] 5: invokestatic #18 // Method T.$init$:(LT;)V [info] 8: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 11: ldc #25 // String C [info] 13: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 16: aload_0 [info] 17: invokestatic #33 // Method T.foo:(LT;)I [info] 20: pop [info] 21: return [info] } > eval "javap -classpath . -c -private T".!! [info] ans: String = Compiled from "test.scala" [info] public interface T { [info] public static int foo(T); [info] Code: [info] 0: iconst_0 [info] 1: ireturn [info] [info] public int foo(); [info] Code: [info] 0: aload_0 [info] 1: invokestatic #15 // Method foo:(LT;)I [info] 4: ireturn [info] [info] public static void $init$(T); [info] Code: [info] 0: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 3: ldc #25 // String T [info] 5: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 8: return [info] [info] public void $init$(); [info] Code: [info] 0: aload_0 [info] 1: invokestatic #32 // Method $init$:(LT;)V [info] 4: return [info] } ```

And use this as the target of the default methods or statically resolved super or $init calls. The call-site change is predicated on `-Yuse-trait-statics` as a stepping stone for experimentation / bootstrapping. I have performed this transformation in the backend, rather than trying to reflect this in the view from Scala symbols + ASTs. Once we commit to this change, we can remove the `lateInterfaces` bookkeeping from the backend, as we no long will need to add ancestor interfaces as direct parents to allow use of invokespecial for super calls. ``` > ;scalac sandbox/test.scala ; scala Test [info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test T C [success] Total time: 2 s, completed 04/05/2016 11:07:13 AM > eval "javap -classpath . -c -private C".!! [info] ans: String = Compiled from "test.scala" [info] public class C implements T { [info] public C(); [info] Code: [info] 0: aload_0 [info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V [info] 4: aload_0 [info] 5: invokespecial #17 // Method T.$init$:()V [info] 8: getstatic #23 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 11: ldc #24 // String C [info] 13: invokevirtual #28 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 16: aload_0 [info] 17: invokespecial #32 // Method T.foo:()I [info] 20: pop [info] 21: return [info] } > ;scalac -Yuse-trait-statics sandbox/test.scala ; scala Test [info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test T C [success] Total time: 2 s, completed 04/05/2016 11:07:39 AM > eval "javap -classpath . -c -private C".!! [info] ans: String = Compiled from "test.scala" [info] public class C implements T { [info] public C(); [info] Code: [info] 0: aload_0 [info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V [info] 4: aload_0 [info] 5: invokestatic #18 // Method T.$init$:(LT;)V [info] 8: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 11: ldc #25 // String C [info] 13: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 16: aload_0 [info] 17: invokestatic #33 // Method T.foo:(LT;)I [info] 20: pop [info] 21: return [info] } > eval "javap -classpath . -c -private T".!! [info] ans: String = Compiled from "test.scala" [info] public interface T { [info] public static int foo(T); [info] Code: [info] 0: iconst_0 [info] 1: ireturn [info] [info] public int foo(); [info] Code: [info] 0: aload_0 [info] 1: invokestatic #15 // Method foo:(LT;)I [info] 4: ireturn [info] [info] public static void $init$(T); [info] Code: [info] 0: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 3: ldc #25 // String T [info] 5: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 8: return [info] [info] public void $init$(); [info] Code: [info] 0: aload_0 [info] 1: invokestatic #32 // Method $init$:(LT;)V [info] 4: return [info] } ```

This corrects an error in the change to the trait encoding in scala#5003: getters in traits should have empty bodies and be emitted as abstract. ``` % ~/scala/2.12.0-M4/bin/scalac sandbox/test.scala && javap -c T Compiled from "test.scala" public interface T { public abstract void T$_setter_$x_$eq(int); public int x(); Code: 0: aload_0 1: invokeinterface #15, 1 // InterfaceMethod x:()I 6: ireturn public int y(); Code: 0: aload_0 1: invokeinterface #20, 1 // InterfaceMethod y:()I 6: ireturn public void y_$eq(int); Code: 0: aload_0 1: iload_1 2: invokeinterface #24, 2 // InterfaceMethod y_$eq:(I)V 7: return public void $init$(); Code: 0: aload_0 1: bipush 42 3: invokeinterface #29, 2 // InterfaceMethod T$_setter_$x_$eq:(I)V 8: aload_0 9: bipush 24 11: invokeinterface #24, 2 // InterfaceMethod y_$eq:(I)V 16: return } % qscalac sandbox/test.scala && javap -c T Compiled from "test.scala" public interface T { public abstract void T$_setter_$x_$eq(int); public abstract int x(); public abstract int y(); public abstract void y_$eq(int); public static void $init$(T); Code: 0: aload_0 1: bipush 42 3: invokeinterface #21, 2 // InterfaceMethod T$_setter_$x_$eq:(I)V 8: aload_0 9: bipush 24 11: invokeinterface #23, 2 // InterfaceMethod y_$eq:(I)V 16: return public void $init$(); Code: 0: aload_0 1: invokestatic #27 // Method $init$:(LT;)V 4: return } ```

And use this as the target of the default methods or statically resolved super or $init calls. The call-site change is predicated on `-Yuse-trait-statics` as a stepping stone for experimentation / bootstrapping. I have performed this transformation in the backend, rather than trying to reflect this in the view from Scala symbols + ASTs. Once we commit to this change, we can remove the `lateInterfaces` bookkeeping from the backend, as we no long will need to add ancestor interfaces as direct parents to allow use of invokespecial for super calls. ``` > ;scalac sandbox/test.scala ; scala Test [info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test T C [success] Total time: 2 s, completed 04/05/2016 11:07:13 AM > eval "javap -classpath . -c -private C".!! [info] ans: String = Compiled from "test.scala" [info] public class C implements T { [info] public C(); [info] Code: [info] 0: aload_0 [info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V [info] 4: aload_0 [info] 5: invokespecial #17 // Method T.$init$:()V [info] 8: getstatic #23 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 11: ldc #24 // String C [info] 13: invokevirtual #28 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 16: aload_0 [info] 17: invokespecial #32 // Method T.foo:()I [info] 20: pop [info] 21: return [info] } > ;scalac -Yuse-trait-statics sandbox/test.scala ; scala Test [info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test T C [success] Total time: 2 s, completed 04/05/2016 11:07:39 AM > eval "javap -classpath . -c -private C".!! [info] ans: String = Compiled from "test.scala" [info] public class C implements T { [info] public C(); [info] Code: [info] 0: aload_0 [info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V [info] 4: aload_0 [info] 5: invokestatic #18 // Method T.$init$:(LT;)V [info] 8: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 11: ldc #25 // String C [info] 13: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 16: aload_0 [info] 17: invokestatic #33 // Method T.foo:(LT;)I [info] 20: pop [info] 21: return [info] } > eval "javap -classpath . -c -private T".!! [info] ans: String = Compiled from "test.scala" [info] public interface T { [info] public static int foo(T); [info] Code: [info] 0: iconst_0 [info] 1: ireturn [info] [info] public int foo(); [info] Code: [info] 0: aload_0 [info] 1: invokestatic #15 // Method foo:(LT;)I [info] 4: ireturn [info] [info] public static void $init$(T); [info] Code: [info] 0: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 3: ldc #25 // String T [info] 5: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 8: return [info] [info] public void $init$(); [info] Code: [info] 0: aload_0 [info] 1: invokestatic #32 // Method $init$:(LT;)V [info] 4: return [info] } ```

This corrects an error in the change to the trait encoding in scala#5003: getters in traits should have empty bodies and be emitted as abstract. ``` % ~/scala/2.12.0-M4/bin/scalac sandbox/test.scala && javap -c T Compiled from "test.scala" public interface T { public abstract void T$_setter_$x_$eq(int); public int x(); Code: 0: aload_0 1: invokeinterface #15, 1 // InterfaceMethod x:()I 6: ireturn public int y(); Code: 0: aload_0 1: invokeinterface #20, 1 // InterfaceMethod y:()I 6: ireturn public void y_$eq(int); Code: 0: aload_0 1: iload_1 2: invokeinterface #24, 2 // InterfaceMethod y_$eq:(I)V 7: return public void $init$(); Code: 0: aload_0 1: bipush 42 3: invokeinterface #29, 2 // InterfaceMethod T$_setter_$x_$eq:(I)V 8: aload_0 9: bipush 24 11: invokeinterface #24, 2 // InterfaceMethod y_$eq:(I)V 16: return } % qscalac sandbox/test.scala && javap -c T Compiled from "test.scala" public interface T { public abstract void T$_setter_$x_$eq(int); public abstract int x(); public abstract int y(); public abstract void y_$eq(int); public static void $init$(T); Code: 0: aload_0 1: bipush 42 3: invokeinterface #21, 2 // InterfaceMethod T$_setter_$x_$eq:(I)V 8: aload_0 9: bipush 24 11: invokeinterface #23, 2 // InterfaceMethod y_$eq:(I)V 16: return public void $init$(); Code: 0: aload_0 1: invokestatic #27 // Method $init$:(LT;)V 4: return } ```

And use this as the target of the default methods or statically resolved super or $init calls. The call-site change is predicated on `-Yuse-trait-statics` as a stepping stone for experimentation / bootstrapping. I have performed this transformation in the backend, rather than trying to reflect this in the view from Scala symbols + ASTs. Once we commit to this change, we can remove the `lateInterfaces` bookkeeping from the backend, as we no long will need to add ancestor interfaces as direct parents to allow use of invokespecial for super calls. ``` > ;scalac sandbox/test.scala ; scala Test [info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test T C [success] Total time: 2 s, completed 04/05/2016 11:07:13 AM > eval "javap -classpath . -c -private C".!! [info] ans: String = Compiled from "test.scala" [info] public class C implements T { [info] public C(); [info] Code: [info] 0: aload_0 [info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V [info] 4: aload_0 [info] 5: invokespecial #17 // Method T.$init$:()V [info] 8: getstatic #23 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 11: ldc #24 // String C [info] 13: invokevirtual #28 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 16: aload_0 [info] 17: invokespecial #32 // Method T.foo:()I [info] 20: pop [info] 21: return [info] } > ;scalac -Yuse-trait-statics sandbox/test.scala ; scala Test [info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test T C [success] Total time: 2 s, completed 04/05/2016 11:07:39 AM > eval "javap -classpath . -c -private C".!! [info] ans: String = Compiled from "test.scala" [info] public class C implements T { [info] public C(); [info] Code: [info] 0: aload_0 [info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V [info] 4: aload_0 [info] 5: invokestatic #18 // Method T.$init$:(LT;)V [info] 8: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 11: ldc #25 // String C [info] 13: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 16: aload_0 [info] 17: invokestatic #33 // Method T.foo:(LT;)I [info] 20: pop [info] 21: return [info] } > eval "javap -classpath . -c -private T".!! [info] ans: String = Compiled from "test.scala" [info] public interface T { [info] public static int foo(T); [info] Code: [info] 0: iconst_0 [info] 1: ireturn [info] [info] public int foo(); [info] Code: [info] 0: aload_0 [info] 1: invokestatic #15 // Method foo:(LT;)I [info] 4: ireturn [info] [info] public static void $init$(T); [info] Code: [info] 0: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 3: ldc #25 // String T [info] 5: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 8: return [info] [info] public void $init$(); [info] Code: [info] 0: aload_0 [info] 1: invokestatic #32 // Method $init$:(LT;)V [info] 4: return [info] } ```

This corrects an error in the change to the trait encoding in scala#5003: getters in traits should have empty bodies and be emitted as abstract. ``` % ~/scala/2.12.0-M4/bin/scalac sandbox/test.scala && javap -c T Compiled from "test.scala" public interface T { public abstract void T$_setter_$x_$eq(int); public int x(); Code: 0: aload_0 1: invokeinterface #15, 1 // InterfaceMethod x:()I 6: ireturn public int y(); Code: 0: aload_0 1: invokeinterface #20, 1 // InterfaceMethod y:()I 6: ireturn public void y_$eq(int); Code: 0: aload_0 1: iload_1 2: invokeinterface #24, 2 // InterfaceMethod y_$eq:(I)V 7: return public void $init$(); Code: 0: aload_0 1: bipush 42 3: invokeinterface #29, 2 // InterfaceMethod T$_setter_$x_$eq:(I)V 8: aload_0 9: bipush 24 11: invokeinterface #24, 2 // InterfaceMethod y_$eq:(I)V 16: return } % qscalac sandbox/test.scala && javap -c T Compiled from "test.scala" public interface T { public abstract void T$_setter_$x_$eq(int); public abstract int x(); public abstract int y(); public abstract void y_$eq(int); public static void $init$(T); Code: 0: aload_0 1: bipush 42 3: invokeinterface #21, 2 // InterfaceMethod T$_setter_$x_$eq:(I)V 8: aload_0 9: bipush 24 11: invokeinterface #23, 2 // InterfaceMethod y_$eq:(I)V 16: return public void $init$(); Code: 0: aload_0 1: invokestatic #27 // Method $init$:(LT;)V 4: return } ```

And use this as the target of the default methods or statically resolved super or $init calls. The call-site change is predicated on `-Yuse-trait-statics` as a stepping stone for experimentation / bootstrapping. I have performed this transformation in the backend, rather than trying to reflect this in the view from Scala symbols + ASTs. Once we commit to this change, we can remove the `lateInterfaces` bookkeeping from the backend, as we no long will need to add ancestor interfaces as direct parents to allow use of invokespecial for super calls. ``` > ;scalac sandbox/test.scala ; scala Test [info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test T C [success] Total time: 2 s, completed 04/05/2016 11:07:13 AM > eval "javap -classpath . -c -private C".!! [info] ans: String = Compiled from "test.scala" [info] public class C implements T { [info] public C(); [info] Code: [info] 0: aload_0 [info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V [info] 4: aload_0 [info] 5: invokespecial #17 // Method T.$init$:()V [info] 8: getstatic #23 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 11: ldc #24 // String C [info] 13: invokevirtual #28 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 16: aload_0 [info] 17: invokespecial #32 // Method T.foo:()I [info] 20: pop [info] 21: return [info] } > ;scalac -Yuse-trait-statics sandbox/test.scala ; scala Test [info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test T C [success] Total time: 2 s, completed 04/05/2016 11:07:39 AM > eval "javap -classpath . -c -private C".!! [info] ans: String = Compiled from "test.scala" [info] public class C implements T { [info] public C(); [info] Code: [info] 0: aload_0 [info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V [info] 4: aload_0 [info] 5: invokestatic #18 // Method T.$init$:(LT;)V [info] 8: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 11: ldc #25 // String C [info] 13: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 16: aload_0 [info] 17: invokestatic #33 // Method T.foo:(LT;)I [info] 20: pop [info] 21: return [info] } > eval "javap -classpath . -c -private T".!! [info] ans: String = Compiled from "test.scala" [info] public interface T { [info] public static int foo(T); [info] Code: [info] 0: iconst_0 [info] 1: ireturn [info] [info] public int foo(); [info] Code: [info] 0: aload_0 [info] 1: invokestatic #15 // Method foo:(LT;)I [info] 4: ireturn [info] [info] public static void $init$(T); [info] Code: [info] 0: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 3: ldc #25 // String T [info] 5: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 8: return [info] [info] public void $init$(); [info] Code: [info] 0: aload_0 [info] 1: invokestatic #32 // Method $init$:(LT;)V [info] 4: return [info] } ```

This corrects an error in the change to the trait encoding in scala#5003: getters in traits should have empty bodies and be emitted as abstract. ``` % ~/scala/2.12.0-M4/bin/scalac sandbox/test.scala && javap -c T Compiled from "test.scala" public interface T { public abstract void T$_setter_$x_$eq(int); public int x(); Code: 0: aload_0 1: invokeinterface #15, 1 // InterfaceMethod x:()I 6: ireturn public int y(); Code: 0: aload_0 1: invokeinterface #20, 1 // InterfaceMethod y:()I 6: ireturn public void y_$eq(int); Code: 0: aload_0 1: iload_1 2: invokeinterface #24, 2 // InterfaceMethod y_$eq:(I)V 7: return public void $init$(); Code: 0: aload_0 1: bipush 42 3: invokeinterface #29, 2 // InterfaceMethod T$_setter_$x_$eq:(I)V 8: aload_0 9: bipush 24 11: invokeinterface #24, 2 // InterfaceMethod y_$eq:(I)V 16: return } % qscalac sandbox/test.scala && javap -c T Compiled from "test.scala" public interface T { public abstract void T$_setter_$x_$eq(int); public abstract int x(); public abstract int y(); public abstract void y_$eq(int); public static void $init$(T); Code: 0: aload_0 1: bipush 42 3: invokeinterface #21, 2 // InterfaceMethod T$_setter_$x_$eq:(I)V 8: aload_0 9: bipush 24 11: invokeinterface #23, 2 // InterfaceMethod y_$eq:(I)V 16: return public void $init$(); Code: 0: aload_0 1: invokestatic #27 // Method $init$:(LT;)V 4: return } ```

And use this as the target of the default methods or statically resolved super or $init calls. The call-site change is predicated on `-Yuse-trait-statics` as a stepping stone for experimentation / bootstrapping. I have performed this transformation in the backend, rather than trying to reflect this in the view from Scala symbols + ASTs. Once we commit to this change, we can remove the `lateInterfaces` bookkeeping from the backend, as we no long will need to add ancestor interfaces as direct parents to allow use of invokespecial for super calls. ``` > ;scalac sandbox/test.scala ; scala Test [info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test T C [success] Total time: 2 s, completed 04/05/2016 11:07:13 AM > eval "javap -classpath . -c -private C".!! [info] ans: String = Compiled from "test.scala" [info] public class C implements T { [info] public C(); [info] Code: [info] 0: aload_0 [info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V [info] 4: aload_0 [info] 5: invokespecial #17 // Method T.$init$:()V [info] 8: getstatic #23 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 11: ldc #24 // String C [info] 13: invokevirtual #28 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 16: aload_0 [info] 17: invokespecial #32 // Method T.foo:()I [info] 20: pop [info] 21: return [info] } > ;scalac -Yuse-trait-statics sandbox/test.scala ; scala Test [info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test T C [success] Total time: 2 s, completed 04/05/2016 11:07:39 AM > eval "javap -classpath . -c -private C".!! [info] ans: String = Compiled from "test.scala" [info] public class C implements T { [info] public C(); [info] Code: [info] 0: aload_0 [info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V [info] 4: aload_0 [info] 5: invokestatic #18 // Method T.$init$:(LT;)V [info] 8: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 11: ldc #25 // String C [info] 13: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 16: aload_0 [info] 17: invokestatic #33 // Method T.foo:(LT;)I [info] 20: pop [info] 21: return [info] } > eval "javap -classpath . -c -private T".!! [info] ans: String = Compiled from "test.scala" [info] public interface T { [info] public static int foo(T); [info] Code: [info] 0: iconst_0 [info] 1: ireturn [info] [info] public int foo(); [info] Code: [info] 0: aload_0 [info] 1: invokestatic #15 // Method foo:(LT;)I [info] 4: ireturn [info] [info] public static void $init$(T); [info] Code: [info] 0: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 3: ldc #25 // String T [info] 5: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 8: return [info] [info] public void $init$(); [info] Code: [info] 0: aload_0 [info] 1: invokestatic #32 // Method $init$:(LT;)V [info] 4: return [info] } ```

And use this as the target of the default methods or statically resolved super or $init calls. The call-site change is predicated on `-Yuse-trait-statics` as a stepping stone for experimentation / bootstrapping. I have performed this transformation in the backend, rather than trying to reflect this in the view from Scala symbols + ASTs. ``` > ;scalac sandbox/test.scala ; scala Test [info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test T C [success] Total time: 2 s, completed 04/05/2016 11:07:13 AM > eval "javap -classpath . -c -private C".!! [info] ans: String = Compiled from "test.scala" [info] public class C implements T { [info] public C(); [info] Code: [info] 0: aload_0 [info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V [info] 4: aload_0 [info] 5: invokespecial #17 // Method T.$init$:()V [info] 8: getstatic #23 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 11: ldc #24 // String C [info] 13: invokevirtual #28 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 16: aload_0 [info] 17: invokespecial #32 // Method T.foo:()I [info] 20: pop [info] 21: return [info] } > ;scalac -Yuse-trait-statics sandbox/test.scala ; scala Test [info] Running scala.tools.nsc.MainGenericRunner -usejavacp Test T C [success] Total time: 2 s, completed 04/05/2016 11:07:39 AM > eval "javap -classpath . -c -private C".!! [info] ans: String = Compiled from "test.scala" [info] public class C implements T { [info] public C(); [info] Code: [info] 0: aload_0 [info] 1: invokespecial #14 // Method java/lang/Object."<init>":()V [info] 4: aload_0 [info] 5: invokestatic #18 // Method T.$init$:(LT;)V [info] 8: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 11: ldc #25 // String C [info] 13: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 16: aload_0 [info] 17: invokestatic #33 // Method T.foo:(LT;)I [info] 20: pop [info] 21: return [info] } > eval "javap -classpath . -c -private T".!! [info] ans: String = Compiled from "test.scala" [info] public interface T { [info] public static int foo(T); [info] Code: [info] 0: iconst_0 [info] 1: ireturn [info] [info] public int foo(); [info] Code: [info] 0: aload_0 [info] 1: invokestatic #15 // Method foo:(LT;)I [info] 4: ireturn [info] [info] public static void $init$(T); [info] Code: [info] 0: getstatic #24 // Field scala/Predef$.MODULE$:Lscala/Predef$; [info] 3: ldc #25 // String T [info] 5: invokevirtual #29 // Method scala/Predef$.println:(Ljava/lang/Object;)V [info] 8: return [info] [info] } ```