Crash when using an annotation in the file where it's defined

[helloqirun]

scalac can compile but dotc crashes.

Perhaps it's related to #1846. But I cannot reproduce that bug any more.

$ dotc -version

Dotty compiler version 0.5.0-bin-SNAPSHOT-git-4fefb64 -- Copyright 2002-2017, LAMP/EPFL

$ cat abc.scala

trait C2[@specialized A]
class specialized extends C2[Char]

$ dotc abc.scala

missing OriginalSymbol for List(type A, class C2, module class <empty>, module class <root>)

exception occurred while typechecking abc.scala

exception occurred while compiling abc.scala
Exception in thread "main" java.util.NoSuchElementException
	at dotty.tools.dotc.util.Attachment$LinkSource.attachment(Attachment.scala:28)
	at dotty.tools.dotc.typer.Typer.op$21(Typer.scala:1061)
	at dotty.tools.dotc.typer.Typer.typedTypeTree(Typer.scala:1056)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:1662)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:1690)
	at dotty.tools.dotc.typer.Typer.op$40(Typer.scala:1707)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:1703)
<snipped>

[odersky]

This has to do with the fact that, due to early processing of annotations we cannot have the definition of an annotation in the same file as its use. It should not crash of course. But since we will want to revisit the decision to handle annotations early we should wait until that's settled.

[smarter]

Already fixed, regression test in #5800.