scala/scala — pull request #2090 by adriaanm (2013-02-07 22:54:28+00:00)
Title: SI-6187 Make partial functions re-typable

(rebase of #2011)

- `New(tpe)` doesn't survive a `resetAttrs` / typecheck; use
a name instead.
- Abandon the tree attachment that passed the default
case from `typer` to `patmat`; this tree eluded the
attribute reset performed in the macro. Instead, add it
to the match. Apart from making the tree re-typable, it
also exposes the true code structure to macros, which
is important if they need to perform other code
transformations.
- Install original trees on the declared types of the
parameters of the `applyOrElse` method to ensure that
references to them within the method pick up the correct
type parameter skolems upon retypechecking.
- Propagate `TypeTree#original` through `copyAttrs`,
which is called during tree duplication / `TreeCopiers`.
Without this, the original trees that we installed were
not visible anymore during `ResetAttrs`.

We are not able to reify partial functions yet -- the
particular sticking point is reification of the parentage
which is only available in the `ClassInfoType`.