Compile-time crash with invalid extractor return type.

Christophe Calvès

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Jul 31, 2015, 9:49:35 AM7/31/15

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Hi all,

I encountered a compiler crash with the following code. Sorry if this is an already known issue (i checked on the issue tracker first, it seemed to be new).

object Extract {
  def unapply[A](a : A) : String = a.toString
}
object Extractor extends App {
  val a = 5 match { case Extract(x) => x  }
}

I am aware that String is not a valid return type for an extractor but it crashes in:

scala.reflect.internal.Types$TypeError: value get is not a member of String
        at scala.tools.nsc.typechecker.Contexts$ThrowingReporter.handleError(Contexts.scala:1390)
        at scala.tools.nsc.typechecker.Contexts$ContextReporter.issue(Contexts.scala:1242)
        at scala.tools.nsc.typechecker.Contexts$Context.issue(Contexts.scala:573)
        at scala.tools.nsc.typechecker.ContextErrors$ErrorUtils$.issueTypeError(ContextErrors.scala:106)
        at scala.tools.nsc.typechecker.ContextErrors$ErrorUtils$.issueNormalTypeError(ContextErrors.scala:99)
        at scala.tools.nsc.typechecker.ContextErrors$TyperContextErrors$TyperErrorGen$.NotAMemberError(ContextErrors.scala:376)
        at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$lookupInQualifier$1(Typers.scala:4095)
        at scala.tools.nsc.typechecker.Typers$Typer.handleMissing$1(Typers.scala:4744)

I tested it on a Linux (Ubuntu 15.04) amd64 machine running Scala version 2.11.7 and 2.11.6 with OpenJDK 64-Bit Server VM, Java 1.7.0_79. Both directly with scalac, in console and with sbt (0.13.8).

Best regards,
Christophe Calvès

Serge

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Jul 31, 2015, 10:51:33 AM7/31/15

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http://hseeberger.github.io/blog/2013/10/04/name-based-extractors-in-scala-2-dot-11/

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Som Snytt

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Jul 31, 2015, 1:50:56 PM7/31/15

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NAME-based is one of those recursive initialisms: NAME-based Anything Makes Exceptions.

We think of issues as having test cases, but really, releases should be characterized by the set of tests which are passing and the set of tests which are pending (known to be failing and accepted as pending issues).

That's my second thought after thinking, How could this be an issue?

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