Compilation error when using shareNothing import and binary output streams

[jportway]

The following code produces a compiler error

import scala.pickling._, scala.pickling.Defaults._
import scala.pickling.binary._
import scala.pickling.shareNothing._

class Tester {
  val vec = "hello world"
  val output = new ByteArrayOutput(1024)
  vec.pickleTo(output)
}

Here's the error produced :

Error:(14, 15) type mismatch;
 found   : <notype>
 required: Unit
  vec.pickleTo(output)
              ^

When pickling to json output it compiles fine

[jsuereth]

So, it looks like this should not work BUT it also should not be issuing a error, see:

> scala.pickling.functions.pickleTo(vec, output)
<console>:22: error: type mismatch;
 found   : output.type (with underlying type scala.pickling.binary.ByteArrayOutput)
 required: ?#OutputType
Note that ByteArrayOutput extends Any, not AnyRef.
Such types can participate in value classes, but instances
cannot appear in singleton types or in reference comparisons.
              scala.pickling.functions.pickleTo(vec, output)
                                                     ^

What's more curious is the following:

> val x: scala.pickling.binary.pickleFormat.OutputType = output
x: pickling.binary.pickleFormat.OutputType = scala.pickling.binary.ByteArrayOutput@1d32af52

scala> vec.pickleTo(x)
<console>:23: error: type mismatch;
 found   : <notype>
 required: Unit
              vec.pickleTo(x)
                          ^

scala> scala.pickling.functions.pickleTo(vec, x)

You can see that explicitly setting the value to be OutputType and using the alternative pickleTo method works...

For now, try the workaround of:

import scala.pickling._, scala.pickling.Defaults._
import scala.pickling.binary._
import scala.pickling.shareNothing._

class Tester {
  val vec = "hello world"
  val output: scala.pickling.binary.pickleFormat.OutputType = new ByteArrayOutput(1024)
  scala.pickling.functions.pickleTo(vec, output)
}

I'll have to investigate why the path-dependent type isn't being used here, but I suspect it's an odd issue in scala's Typer combined with our overly-eager type setup.