Add array tracing from PR #120.

[albertnetymk]

Variables with parametric type are not properly traced, which should be taken care of in another PR.

[albertnetymk]

streams.enc is breaking the build. In fact, streams are not supported, for it shares unfulfilled futures.

[EliasC]

@albertnetymk Could you try to make the stream non-polymorphic? I.e. change the streaming method interleave to

  stream interleave(s1 : Stream int, s2 : Stream int) : int{
    while ((not eos s1) and (not eos s2)) {
      yield get s1;
      yield get s2;
      s1 = getNext s1;
      s2 = getNext s2;
    }
  }

[albertnetymk]

@EliasC Why does it make any difference? The reason why stream fails is not because it's using polymorphic type. Instead, it's because it's sharing futures underneath.

[EliasC]

@albertnetymk It's one less error source to worry about. This PR changes tracing, something that we know doesn't work well for polymorphic values, and this test has passed before, so it's worth a try.

[albertnetymk]

@EliasC Sure. However, the origial streams.enc uses int for polymorphic type variable anyway, so nothing to trace. It was working before by accident, I believe. The backend has never been correctly implemented to support streams, if using pony_allloc. The same argument goes for largestream.enc.

[EliasC]

@albertnetymk Then maybe we should consider removing streams.enc from the Jenkins build as well? No point in being alerted that something we know is broken is broken. What is your opinion @kikofernandez?

[albertnetymk]

Rebaesd onto 871a17b. Build fails for async_force_gc, async_foreach, and streams, which is expected.