scala/scala — pull request #659 by retronym (2012-06-03 10:42:21+00:00)
Title: SI-5167 An impl class method should refer to its own parameter symbols.

Rather than those of the original method in the trait.

If they are shared, parameter renaming in the implementaion class
is visible in the original method. This led to a crash in the resident
compiler when looking up the default argument getter.

Review by @odersky

Discussion: https://groups.google.com/d/topic/scala-internals/sPjmxv-A2iE/discussion