Commits on Sep 6, 2013

1. SI-7818 Cast our way out of extended existential angst …

   `substituteSymbols` is not sophisticated enough to
   operate on `TypeSkolem`-s which are based on one of the
   "from" symbols.
   
   The pertinant usage of `substituteSymbols` for this bug in
   in `Extender`. Recapping on that transform:
   
       // orig
       class C[T](...) extends AnyVal { def foo[U] = <rhs> }
   
       // transform
       class C[T] extends AnyVal { ... }
       object C  { def foo$extension[T', U'] = <rhs'> }
   
   Where `<rhs'>` has been subtituted with, among other things,
   `[T, U] ~> [T', U']`.
   
   In this case our expected type contains a new type parameter
   (of the extension method), whereas the type of the RHS contains
   an existential skolem still pinned to the corresponding class type
   parameter.
   
       tree.tpe         = Observable1#7037[_$1#12344]
       <_$1#12344>.info =  <: T#7040
       pt               = Observable1#7037[T#15644]
   
   The limitation of substution is lamented in the comments
   of `adaptMismatchedSkolems`, which faces the harder version of
   the issue where the skolems are in the expected type.
   
   But, we're in the "easy" case with the skolems in the tree's type;
   we can cast our way out of the problem.
   
   See also f335e44 / ed915c5.

   

   retronym committed Sep 6, 2013
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