Imported From: https://issues.scala-lang.org/browse/SI-8051?orig=1
Reporter: @refried
Affected Versions: 2.10.3
Duplicates #7912

@jroper said:
Problem here seems to be that MatchError.getMessage is throwing itself again:

Welcome to Scala version 2.10.3 (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_65).
Type in expressions to have them evaluated.
Type :help for more information.

scala> :paste
// Entering paste mode (ctrl-D to finish)

trait X {
  override def toString = this match{
    case Z(z) => z.toString
  }
}
case class Y(y: Int) extends X
case class Z(z: Int) extends X

try { 
  Y(0).toString
} catch {
  case e: Exception =>
    try {
      e.getMessage
    } catch {
      case t: Exception => "Exception.getMessage threw the following exception: " + t.getClass
    }
}

// Exiting paste mode, now interpreting.

defined trait X
defined class Y
defined class Z
res0: String = Exception.getMessage threw the following exception: class scala.MatchError

Anything that attempts to report anything about this error will itself throw an exception when it tries to call getMessage, and since getMessage is rethrowing the exception, this will defeat every single layer of error reporting.

@jroper said:
Related Play issue:

playframework/playframework#2138

@refried said (edited on Dec 9, 2013 4:35:20 AM UTC):
Thanks for digging into that.

I'm guessing it's not re-throwing it per se, but trying to print the expression that failed to match; but printing the expression is what causes the match failure.

@retronym said:
Duplicate of #7912

@jroper said:
I should have realised this was a duplicate of a bug that I myself reported!

@refried said:
Yeah, I wasn't expecting that either.