Another test pack for reflection #29

xeno-by · 2011-12-05T16:01:55Z

Also see #25.

Jribble+jvm backends.

The REPL :java -app command is a convenience to locate the body of DelayedInit code. Now it will look for new style delayedEndpoints on the class before it falls back to showing the apply method of the delayedInit$body closure. ``` apm@mara:~/tmp$ skala Welcome to Scala version 2.11.0-20130711-153246-eb1c3137f5 (OpenJDK 64-Bit Server VM, Java 1.7.0_21). Type in expressions to have them evaluated. Type :help for more information. scala> :javap -pv -app delayed.C public final void delayedEndpoint$delayed$C$1(); flags: ACC_PUBLIC, ACC_FINAL Code: stack=2, locals=1, args_size=1 0: getstatic scala#29 // Field scala/Predef$.MODULE$:Lscala/Predef$; 3: ldc scala#31 // String this is the initialization code of C 5: invokevirtual scala#35 // Method scala/Predef$.println:(Ljava/lang/Object;)V 8: return LocalVariableTable: Start Length Slot Name Signature 0 9 0 this Ldelayed/C; LineNumberTable: line 11: 0 scala> :q apm@mara:~/tmp$ rm delayed/*.class apm@mara:~/tmp$ scalac delayed.scala apm@mara:~/tmp$ skala Welcome to Scala version 2.11.0-20130711-153246-eb1c3137f5 (OpenJDK 64-Bit Server VM, Java 1.7.0_21). Type in expressions to have them evaluated. Type :help for more information. scala> :javap -pv -app delayed.C public final java.lang.Object apply(); flags: ACC_PUBLIC, ACC_FINAL Code: stack=2, locals=1, args_size=1 0: getstatic scala#13 // Field scala/Predef$.MODULE$:Lscala/Predef$; 3: ldc scala#15 // String this is the initialization code of C 5: invokevirtual scala#19 // Method scala/Predef$.println:(Ljava/lang/Object;)V 8: getstatic scala#25 // Field scala/runtime/BoxedUnit.UNIT:Lscala/runtime/BoxedUnit; 11: areturn LocalVariableTable: Start Length Slot Name Signature 0 12 0 this Ldelayed/C$delayedInit$body; LineNumberTable: line 11: 0 line 10: 8 ```

Allow primes at the end of identifiers.

These methods are "signature polymorphic", which means that compiler should not: a) adapt the arguments to `Object` b) wrap the repeated parameters in an array c) adapt the result type to `Object` if the enclosing expression is a cast or if the application appears in the statement position of a block. Dispiritingly, my initial attempt to implement this touched the type checker, uncurry, erasure, and the backend. However, I realized we could centralize handling of this in the typer if at each application we substituted the signature polymorphic symbol with a clone that carried its implied signature, which is derived from the types of the arguments (typechecked without an expected type) and position within and enclosing cast or block. The test case requires Java 7+ to compile so is currently embedded in a conditionally compiled block of code in a run test. We ought to create a partest category for modern JVMs so we can write such tests in a more natural style. Here's how this looks in bytecode. Note the `bipush` / `istore` before/after the invocation of `invokeExact`, and the descriptor `(LO$;I)I`. ``` % cat sandbox/poly-sig.scala && qscala Test && echo ':javap Test$#main' | qscala import java.lang.invoke._ object O { def bar(x: Int): Int = -x } object Test { def main(args: Array[String]): Unit = { def lookup(name: String, params: Array[Class[_]], ret: Class[_]) = { val lookup = java.lang.invoke.MethodHandles.lookup val mt = MethodType.methodType(ret, params) lookup.findVirtual(O.getClass, name, mt) } def lookupBar = lookup("bar", Array(classOf[Int]), classOf[Int]) val barResult = lookupBar.invokeExact(O, 42).asInstanceOf[Int] () } } scala> :javap Test$#main public void main(java.lang.String[]); descriptor: ([Ljava/lang/String;)V flags: ACC_PUBLIC Code: stack=3, locals=3, args_size=2 0: aload_0 1: invokespecial #18 // Method lookupBar$1:()Ljava/lang/invoke/MethodHandle; 4: getstatic #23 // Field O$.MODULE$:LO$; 7: bipush 42 9: invokevirtual #29 // Method java/lang/invoke/MethodHandle.invokeExact:(LO$;I)I 12: istore_2 13: return LocalVariableTable: Start Length Slot Name Signature 0 14 0 this LTest$; 0 14 1 args [Ljava/lang/String; 13 0 2 barResult I LineNumberTable: line 16: 0 } ``` I've run this test across our active JVMs: ``` % for v in 1.6 1.7 1.8; do java_use $v; pt --terse test/files/run/t7965.scala || break; done java version "1.6.0_65" Java(TM) SE Runtime Environment (build 1.6.0_65-b14-466.1-11M4716) Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-466.1, mixed mode) Selected 1 tests drawn from specified tests # starting 1 test in run . 1/1 passed (elapsed time: 00:00:02) Test Run PASSED java version "1.7.0_71" Java(TM) SE Runtime Environment (build 1.7.0_71-b14) Java HotSpot(TM) 64-Bit Server VM (build 24.71-b01, mixed mode) Selected 1 tests drawn from specified tests # starting 1 test in run . 1/1 passed (elapsed time: 00:00:07) Test Run PASSED java version "1.8.0_25" Java(TM) SE Runtime Environment (build 1.8.0_25-b17) Java HotSpot(TM) 64-Bit Server VM (build 25.25-b02, mixed mode) Selected 1 tests drawn from specified tests # starting 1 test in run . 1/1 passed (elapsed time: 00:00:05) Test Run PASSED ``` # Please enter the commit message for your changes. Lines starting # with '#' will be ignored, and an empty message aborts the commit. # # Date: Thu Nov 20 23:26:16 2014 +1000 # # On branch ticket/7965 # Your branch is up-to-date with 'retronym/ticket/7965'. # # Changes to be committed: # modified: src/compiler/scala/tools/nsc/typechecker/Typers.scala # modified: src/reflect/scala/reflect/internal/Definitions.scala # modified: src/reflect/scala/reflect/internal/StdNames.scala # new file: test/files/run/t7965.scala # # Untracked files: # pack/ #

These methods are "signature polymorphic", which means that compiler should not: a. adapt the arguments to `Object` b. wrap the repeated parameters in an array c. adapt the result type to `Object` if the enclosing expression is a cast or if the application appears in the statement position of a block. Dispiritingly, my initial attempt to implement this touched the type checker, uncurry, erasure, and the backend. However, I realized we could centralize handling of this in the typer if at each application we substituted the signature polymorphic symbol with a clone that carried its implied signature, which is derived from the types of the arguments (typechecked without an expected type) and position within and enclosing cast or block. The test case requires Java 7+ to compile so is currently embedded in a conditionally compiled block of code in a run test. We ought to create a partest category for modern JVMs so we can write such tests in a more natural style. Here's how this looks in bytecode. Note the `bipush` / `istore` before/after the invocation of `invokeExact`, and the descriptor `(LO$;I)I`. ``` % cat sandbox/poly-sig.scala && qscala Test && echo ':javap Test$#main' | qscala import java.lang.invoke._ object O { def bar(x: Int): Int = -x } object Test { def main(args: Array[String]): Unit = { def lookup(name: String, params: Array[Class[_]], ret: Class[_]) = { val lookup = java.lang.invoke.MethodHandles.lookup val mt = MethodType.methodType(ret, params) lookup.findVirtual(O.getClass, name, mt) } def lookupBar = lookup("bar", Array(classOf[Int]), classOf[Int]) val barResult = lookupBar.invokeExact(O, 42).asInstanceOf[Int] () } } scala> :javap Test$#main public void main(java.lang.String[]); descriptor: ([Ljava/lang/String;)V flags: ACC_PUBLIC Code: stack=3, locals=3, args_size=2 0: aload_0 1: invokespecial #18 // Method lookupBar$1:()Ljava/lang/invoke/MethodHandle; 4: getstatic #23 // Field O$.MODULE$:LO$; 7: bipush 42 9: invokevirtual #29 // Method java/lang/invoke/MethodHandle.invokeExact:(LO$;I)I 12: istore_2 13: return LocalVariableTable: Start Length Slot Name Signature 0 14 0 this LTest$; 0 14 1 args [Ljava/lang/String; 13 0 2 barResult I LineNumberTable: line 16: 0 } ``` I've run this test across our active JVMs: ``` % for v in 1.6 1.7 1.8; do java_use $v; pt --terse test/files/run/t7965.scala || break; done java version "1.6.0_65" Java(TM) SE Runtime Environment (build 1.6.0_65-b14-466.1-11M4716) Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-466.1, mixed mode) Selected 1 tests drawn from specified tests . 1/1 passed (elapsed time: 00:00:02) Test Run PASSED java version "1.7.0_71" Java(TM) SE Runtime Environment (build 1.7.0_71-b14) Java HotSpot(TM) 64-Bit Server VM (build 24.71-b01, mixed mode) Selected 1 tests drawn from specified tests . 1/1 passed (elapsed time: 00:00:07) Test Run PASSED java version "1.8.0_25" Java(TM) SE Runtime Environment (build 1.8.0_25-b17) Java HotSpot(TM) 64-Bit Server VM (build 25.25-b02, mixed mode) Selected 1 tests drawn from specified tests . 1/1 passed (elapsed time: 00:00:05) Test Run PASSED ```

These methods are "signature polymorphic", which means that compiler should not: 1. adapt the arguments to `Object` 2. wrap the repeated parameters in an array 3. adapt the result type to `Object` if the enclosing expression is a cast or if the application appears in the statement position of a block. Dispiritingly, my initial attempt to implement this touched the type checker, uncurry, erasure, and the backend. However, I realized we could centralize handling of this in the typer if at each application we substituted the signature polymorphic symbol with a clone that carried its implied signature, which is derived from the types of the arguments (typechecked without an expected type) and position within and enclosing cast or block. The test case requires Java 7+ to compile so is currently embedded in a conditionally compiled block of code in a run test. We ought to create a partest category for modern JVMs so we can write such tests in a more natural style. Here's how this looks in bytecode. Note the `bipush` / `istore` before/after the invocation of `invokeExact`, and the descriptor `(LO$;I)I`. ``` % cat sandbox/poly-sig.scala && qscala Test && echo ':javap Test$#main' | qscala import java.lang.invoke._ object O { def bar(x: Int): Int = -x } object Test { def main(args: Array[String]): Unit = { def lookup(name: String, params: Array[Class[_]], ret: Class[_]) = { val lookup = java.lang.invoke.MethodHandles.lookup val mt = MethodType.methodType(ret, params) lookup.findVirtual(O.getClass, name, mt) } def lookupBar = lookup("bar", Array(classOf[Int]), classOf[Int]) val barResult = lookupBar.invokeExact(O, 42).asInstanceOf[Int] () } } scala> :javap Test$#main public void main(java.lang.String[]); descriptor: ([Ljava/lang/String;)V flags: ACC_PUBLIC Code: stack=3, locals=3, args_size=2 0: aload_0 1: invokespecial #18 // Method lookupBar$1:()Ljava/lang/invoke/MethodHandle; 4: getstatic #23 // Field O$.MODULE$:LO$; 7: bipush 42 9: invokevirtual #29 // Method java/lang/invoke/MethodHandle.invokeExact:(LO$;I)I 12: istore_2 13: return LocalVariableTable: Start Length Slot Name Signature 0 14 0 this LTest$; 0 14 1 args [Ljava/lang/String; 13 0 2 barResult I LineNumberTable: line 16: 0 } ``` I've run this test across our active JVMs: ``` % for v in 1.6 1.7 1.8; do java_use $v; pt --terse test/files/run/t7965.scala || break; done java version "1.6.0_65" Java(TM) SE Runtime Environment (build 1.6.0_65-b14-466.1-11M4716) Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-466.1, mixed mode) Selected 1 tests drawn from specified tests . 1/1 passed (elapsed time: 00:00:02) Test Run PASSED java version "1.7.0_71" Java(TM) SE Runtime Environment (build 1.7.0_71-b14) Java HotSpot(TM) 64-Bit Server VM (build 24.71-b01, mixed mode) Selected 1 tests drawn from specified tests . 1/1 passed (elapsed time: 00:00:07) Test Run PASSED java version "1.8.0_25" Java(TM) SE Runtime Environment (build 1.8.0_25-b17) Java HotSpot(TM) 64-Bit Server VM (build 25.25-b02, mixed mode) Selected 1 tests drawn from specified tests . 1/1 passed (elapsed time: 00:00:05) Test Run PASSED ``` # Please enter the commit message for your changes. Lines starting # with '#' will be kept; you may remove them yourself if you want to. # An empty message aborts the commit. # # Date: Thu Nov 20 23:26:16 2014 +1000 # # On branch ticket/7965 # Your branch is up-to-date with 'retronym/ticket/7965'. # # Changes to be committed: # modified: src/compiler/scala/tools/nsc/typechecker/Typers.scala # modified: src/reflect/scala/reflect/internal/Definitions.scala # modified: src/reflect/scala/reflect/internal/StdNames.scala # new file: test/files/run/t7965.scala # # Untracked files: # pack/ #

These methods are "signature polymorphic", which means that compiler should not: 1. adapt the arguments to `Object` 2. wrap the repeated parameters in an array 3. adapt the result type to `Object` if the enclosing expression is a cast or if the application appears in the statement position of a block. Dispiritingly, my initial attempt to implement this touched the type checker, uncurry, erasure, and the backend. However, I realized we could centralize handling of this in the typer if at each application we substituted the signature polymorphic symbol with a clone that carried its implied signature, which is derived from the types of the arguments (typechecked without an expected type) and position within and enclosing cast or block. The test case requires Java 7+ to compile so is currently embedded in a conditionally compiled block of code in a run test. We ought to create a partest category for modern JVMs so we can write such tests in a more natural style. Here's how this looks in bytecode. Note the `bipush` / `istore` before/after the invocation of `invokeExact`, and the descriptor `(LO$;I)I`. ``` % cat sandbox/poly-sig.scala && qscala Test && echo ':javap Test$#main' | qscala import java.lang.invoke._ object O { def bar(x: Int): Int = -x } object Test { def main(args: Array[String]): Unit = { def lookup(name: String, params: Array[Class[_]], ret: Class[_]) = { val lookup = java.lang.invoke.MethodHandles.lookup val mt = MethodType.methodType(ret, params) lookup.findVirtual(O.getClass, name, mt) } def lookupBar = lookup("bar", Array(classOf[Int]), classOf[Int]) val barResult = lookupBar.invokeExact(O, 42).asInstanceOf[Int] () } } scala> :javap Test$#main public void main(java.lang.String[]); descriptor: ([Ljava/lang/String;)V flags: ACC_PUBLIC Code: stack=3, locals=3, args_size=2 0: aload_0 1: invokespecial #18 // Method lookupBar$1:()Ljava/lang/invoke/MethodHandle; 4: getstatic #23 // Field O$.MODULE$:LO$; 7: bipush 42 9: invokevirtual #29 // Method java/lang/invoke/MethodHandle.invokeExact:(LO$;I)I 12: istore_2 13: return LocalVariableTable: Start Length Slot Name Signature 0 14 0 this LTest$; 0 14 1 args [Ljava/lang/String; 13 0 2 barResult I LineNumberTable: line 16: 0 } ``` I've run this test across our active JVMs: ``` % for v in 1.6 1.7 1.8; do java_use $v; pt --terse test/files/run/t7965.scala || break; done java version "1.6.0_65" Java(TM) SE Runtime Environment (build 1.6.0_65-b14-466.1-11M4716) Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-466.1, mixed mode) Selected 1 tests drawn from specified tests . 1/1 passed (elapsed time: 00:00:02) Test Run PASSED java version "1.7.0_71" Java(TM) SE Runtime Environment (build 1.7.0_71-b14) Java HotSpot(TM) 64-Bit Server VM (build 24.71-b01, mixed mode) Selected 1 tests drawn from specified tests . 1/1 passed (elapsed time: 00:00:07) Test Run PASSED java version "1.8.0_25" Java(TM) SE Runtime Environment (build 1.8.0_25-b17) Java HotSpot(TM) 64-Bit Server VM (build 25.25-b02, mixed mode) Selected 1 tests drawn from specified tests . 1/1 passed (elapsed time: 00:00:05) Test Run PASSED ```

These methods are "signature polymorphic", which means that compiler should not: 1. adapt the arguments to `Object` 2. wrap the repeated parameters in an array 3. adapt the result type to `Object`, but instead treat it as it it already conforms to the expected type. Dispiritingly, my initial attempt to implement this touched the type checker, uncurry, erasure, and the backend. However, I realized we could centralize handling of this in the typer if at each application we substituted the signature polymorphic symbol with a clone that carried its implied signature, which is derived from the types of the arguments (typechecked without an expected type) and position within and enclosing cast or block. The test case requires Java 7+ to compile so is currently embedded in a conditionally compiled block of code in a run test. We ought to create a partest category for modern JVMs so we can write such tests in a more natural style. Here's how this looks in bytecode. Note the `bipush` / `istore` before/after the invocation of `invokeExact`, and the descriptor `(LO$;I)I`. ``` % cat sandbox/poly-sig.scala && qscala Test && echo ':javap Test$#main' | qscala import java.lang.invoke._ object O { def bar(x: Int): Int = -x } object Test { def main(args: Array[String]): Unit = { def lookup(name: String, params: Array[Class[_]], ret: Class[_]) = { val lookup = java.lang.invoke.MethodHandles.lookup val mt = MethodType.methodType(ret, params) lookup.findVirtual(O.getClass, name, mt) } def lookupBar = lookup("bar", Array(classOf[Int]), classOf[Int]) val barResult: Int = lookupBar.invokeExact(O, 42) () } } scala> :javap Test$#main public void main(java.lang.String[]); descriptor: ([Ljava/lang/String;)V flags: ACC_PUBLIC Code: stack=3, locals=3, args_size=2 0: aload_0 1: invokespecial #18 // Method lookupBar$1:()Ljava/lang/invoke/MethodHandle; 4: getstatic #23 // Field O$.MODULE$:LO$; 7: bipush 42 9: invokevirtual #29 // Method java/lang/invoke/MethodHandle.invokeExact:(LO$;I)I 12: istore_2 13: return LocalVariableTable: Start Length Slot Name Signature 0 14 0 this LTest$; 0 14 1 args [Ljava/lang/String; 13 0 2 barResult I LineNumberTable: line 16: 0 } ``` I've run this test across our active JVMs: ``` % for v in 1.6 1.7 1.8; do java_use $v; pt --terse test/files/run/t7965.scala || break; done java version "1.6.0_65" Java(TM) SE Runtime Environment (build 1.6.0_65-b14-466.1-11M4716) Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-466.1, mixed mode) Selected 1 tests drawn from specified tests . 1/1 passed (elapsed time: 00:00:02) Test Run PASSED java version "1.7.0_71" Java(TM) SE Runtime Environment (build 1.7.0_71-b14) Java HotSpot(TM) 64-Bit Server VM (build 24.71-b01, mixed mode) Selected 1 tests drawn from specified tests . 1/1 passed (elapsed time: 00:00:07) Test Run PASSED java version "1.8.0_25" Java(TM) SE Runtime Environment (build 1.8.0_25-b17) Java HotSpot(TM) 64-Bit Server VM (build 25.25-b02, mixed mode) Selected 1 tests drawn from specified tests . 1/1 passed (elapsed time: 00:00:05) Test Run PASSED ```

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] } ```