I believe this is scala bug 7521: https://github.com/scala/bug/issues/7521
Skimming the comments and other referenced issues, I don't see anyone mentioning a workaround. Appears the fix was added in 2.12, which makes sense based on the behavior you're seeing. On 12/17/19 1:19 PM, Sloane, Brandon wrote: > While debugging my latest DataValue PR under 2.11, I came across what I > believe to be a compiler bug. > > Recall that we have source code along the lines of: > > ... > @inline implicit def toDataValue(v: DFDLTime): DataValueTime = new > DataValue(v) > @inline implicit def toDataValue(v: Array[Byte]): DataValueByteArray = new > DataValue(v) > @inline implicit def toDataValue(v: JBoolean): DataValueBool = new > DataValue(v) > @inline implicit def toDataValue(v: JNumber): DataValueNumber = new > DataValue(v) > ... > > Under 2.11, this gets compiled to: > > ... > public org.apache.daffodil.calendar.DFDLDate > toDataValue(org.apache.daffodil.calendar.DFDLDate); > Code: > 0: aload_1 > 1: areturn > > public org.apache.daffodil.calendar.DFDLTime > toDataValue(org.apache.daffodil.calendar.DFDLTime); > Code: > 0: aload_1 > 1: areturn > > public byte[] toDataValue(byte[]); > Code: > 0: getstatic #35 // Field > scala/runtime/ScalaRunTime$.MODULE$:Lscala/runtime/ScalaRunTime$; > 3: aload_1 > 4: invokevirtual #39 // Method > scala/runtime/ScalaRunTime$.toObjectArray:(Ljava/lang/Object;)[Ljava/lang/Object; > 7: checkcast #41 // class "[Ljava/lang/Byte;" > 10: areturn > > public java.lang.Boolean toDataValue(java.lang.Boolean); > Code: > 0: aload_1 > 1: areturn > > public java.lang.Number toDataValue(java.lang.Number); > Code: > 0: aload_1 > 1: areturn > ... > > Note that for every instant accept byte[], the function compiles to a simple > identity function. > > When compiled under 2.12, the byte[] instance gets compiled to identity as > well: > > public byte[] toDataValue(byte[]); > Code: > 0: aload_1 > 1: areturn > > The 2.11 version is not just inefficient; it is also wrong. It first converts > to an array of Objects (which implies boxing), before attempting to cast said > array to an array of (boxed) Bytes. This case fails , as Object[] does not > extends Byte[]. > > Even if this cast were to succeed, the function would then be attempting to > return an array of boxed java.lang.Byte, while its signature indicates it > should be returning an array of unboxed bytes. > > (As an asside, at the callpoint I looked at in 2.12 optimizes this function > out entirely; the 2.11 version makes a standard function call to toDataValue) > > I'm at a bit of a loss as to how to proceed. This bug seems fatal to the idea > of having an AnyVal DataValue class, and we do not have much wiggle-room to > tweak our source code to avoid triggering it. > > Thoughts? > > > Brandon T. Sloane > > Associate, Services > > bslo...@tresys.com | tresys.com >
