[indylambda] Relieve LambdaMetafactory of boxing duties

`LambdaMetafactory` generates code to perform a limited number
of type adaptations when delegating from its implementation of
the functional interface method to the lambda target method.

These adaptations are: numeric widening, casting, boxing and unboxing.

However, the semantics of unboxing numerics in Java differs to Scala:
they treat `UNBOX(null)` as cause to raise a `NullPointerException`,
Scala (in `BoxesRuntime.unboxTo{Byte,Short,...}`) reinterprets the
null as zero.

Furthermore, Java has no idea how to adapt between a value class and
its wrapped type, nor from a void return to `BoxedUnit`.

This commit detects when the lambda target method would require
such adaptation. If it does, an extra method, `$anonfun$1$adapted` is
created to perform the adaptation, and this is used as the target
of the lambda.

This obviates the use of `JProcedureN` for `Unit` returning
lambdas, we know use `JFunctionN` as the functional interface
and bind this to an `$adapted` method that summons the instance
of `BoxedUnit` after calling the `void` returning lambda target.

The enclosed test cases fail without boxing changes. They don't
execute with indylambda enabled under regular partest runs yet,
you need to add scala-java8-compat to scala-library and pass
the SCALAC_OPTS to partest manually to try this out, as described
in https://github.com/scala/scala/pull/4463. Once we enable indylambda
by default, however, this test will exercise the code in this patch
all the time.

It is also possible to run the tests with:

```
% curl https://oss.sonatype.org/content/repositories/releases/org/scala-lang/modules/scala-java8-compat_2.11/0.4.0/scala-java8-compat_2.11-0.4.0.jar > scala-java8-compat_2.11-0.4.0.jar
% export INDYLAMBDA="-Ydelambdafy:method -Ybackend:GenBCode -target:jvm-1.8 -classpath .:scala-java8-compat_2.11-0.4.0.jar"
qscalac $INDYLAMBDA test/files/run/indylambda-boxing/*.scala && qscala $INDYLAMBDA Test
```

2 files changed, 3 insertions, 3 deletions

diff --git a/src/reflect/scala/reflect/internal/Definitions.scala b/src/reflect/scala/reflect/internal/Definitions.scala
index 5b20d9db8e..73ffb267a9 100644
--- a/src/reflect/scala/reflect/internal/Definitions.scala
+++ b/src/reflect/scala/reflect/internal/Definitions.scala
@@ -1515,8 +1515,7 @@ trait Definitions extends api.StandardDefinitions {
       private lazy val PolySigMethods: Set[Symbol] = Set[Symbol](MethodHandle.info.decl(sn.Invoke), MethodHandle.info.decl(sn.InvokeExact)).filter(_.exists)
 
       lazy val Scala_Java8_CompatPackage = rootMirror.getPackageIfDefined("scala.compat.java8")
-      lazy val Scala_Java8_CompatPackage_JFunction = (0 to MaxTupleArity).toArray map (i => getMemberIfDefined(Scala_Java8_CompatPackage.moduleClass, TypeName("JFunction" + i)))
-      lazy val Scala_Java8_CompatPackage_JProcedure = (0 to MaxTupleArity).toArray map (i => getMemberIfDefined(Scala_Java8_CompatPackage.moduleClass, TypeName("JProcedure" + i)))
+      lazy val Scala_Java8_CompatPackage_JFunction = (0 to MaxFunctionArity).toArray map (i => getMemberIfDefined(Scala_Java8_CompatPackage.moduleClass, TypeName("JFunction" + i)))
     }
   }
 }
diff --git a/src/reflect/scala/reflect/internal/transform/PostErasure.scala b/src/reflect/scala/reflect/internal/transform/PostErasure.scala
index dd4f044818..466c6133b2 100644
--- a/src/reflect/scala/reflect/internal/transform/PostErasure.scala
+++ b/src/reflect/scala/reflect/internal/transform/PostErasure.scala
@@ -9,7 +9,8 @@ trait PostErasure {
   object elimErasedValueType extends TypeMap {
     def apply(tp: Type) = tp match {
       case ConstantType(Constant(tp: Type)) => ConstantType(Constant(apply(tp)))
-      case ErasedValueType(_, underlying)   => underlying
+      case ErasedValueType(_, underlying)   =>
+        underlying
       case _                                => mapOver(tp)
     }
   }