Memory leak in symbol attachments

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Symbol attachments leak through the $outer pointer. Proof is in this gist:

https://gist.github.com/4622507

You need to have an input file for that to work, place the one in the gist it under ./src (the directory from where you'll run the test).

The attachments leak instances of NonemptyAttachments through the outer pointer (in this case, there's a chain of 101 instances).

The problem is that NonemptyAttachments extends its own outer class (yeah, it takes a while to grok this), so every time you create a new instance, you capture the outer instance.. which happens to be another instance of NonemptyAttachments. That's a very interesting way to create linked lists, but in this case I'm pretty sure it's unintended.

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Imported From: https://issues.scala-lang.org/browse/SI-7018?orig=1
Reporter: @dragos
Affected Versions: 2.10.0

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@retronym said:
scala/scala#1977