more error message toys I wrote this weekend

** Demo 1 **

% SOURCEPATH=/scala/trunk/src scala -Yrich-exceptions
Welcome to Scala version 2.8.0.r21946-b20100516204551 (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_17).
Type in expressions to have them evaluated.
Type :help for more information.

scala> Nil(-1)
java.lang.IndexOutOfBoundsException
[LinearSeqOptimized.apply]
50: def apply(n: Int): A = {
51: val rest = drop(n)
52: if (n < 0 || rest.isEmpty) throw new IndexOutOfBoundsException
*53: rest.head
54: }
55:
56: override /*IterableLike*/

[List.apply]
42: * @define willNotTerminateInf
43: */
44: sealed abstract class List[+A] extends LinearSeq[A]
*45: with Product
46: with GenericTraversableTemplate[A, List]
47: with LinearSeqOptimized[A, List[A]] {
48: override def companion: GenericCompanion[List] = List

// I snip the remainder

** Demo 2 **

Crasher taken from: https://lampsvn.epfl.ch/trac/scala/ticket/3431

scala> val url = new java.net.URL( "http://www.sciss.de/index.html" )
url: java.net.URL = http://www.sciss.de/index.html

scala> val is = url.openStream
is: java.io.InputStream = sun.net.www.protocol.http.HttpURLConnection$HttpInputStream@5bc935cc

scala> is.
assertion failed: class HttpURLConnection: package http
[searching sources for exception contexts...]
[Predef.assert]
89: def assert(assertion: Boolean, message: => Any) {
90: if (!assertion)
91: throw new java.lang.AssertionError("assertion failed: "+ message)
*92: }
93:
94: /** Tests an expression, throwing an AssertionError if false.
95: * This method differs from assert only in the intent expressed:

[ClassfileParser.parseMethod]
600: val newParams = innerClasses.get(externalName) match {
601: case Some(entry) if !isScalaRaw && !isStatic(entry.jflags) =>
602: assert(params.head.tpe.typeSymbol == clazz.owner, params.head.tpe.typeSymbol + ": " + clazz.owner)
*603: params.tail
604: case _ =>
605: params
606: }

[ClassfileParser.apply$mcVI$sp]
522: sawPrivateConstructor = false
523: val methodCount = in.nextChar
524: for (i <- 0 until methodCount) parseMethod()
*525: if (!sawPrivateConstructor &&
526: (instanceDefs.lookup(nme.CONSTRUCTOR) == NoSymbol &&
527: (sflags & INTERFACE) == 0L))
528: {

[ClassfileParser.apply]
522: sawPrivateConstructor = false
523: val methodCount = in.nextChar
524: for (i <- 0 until methodCount) parseMethod()
*525: if (!sawPrivateConstructor &&
526: (instanceDefs.lookup(nme.CONSTRUCTOR) == NoSymbol &&
527: (sflags & INTERFACE) == 0L))
528: {

// I snip the remainder

** Demo 3 - same REPL session where the compiler just exploded **

Attempting recovery...
Replaying: val url = new java.net.URL( "http://www.sciss.de/index.html" )
url: java.net.URL = http://www.sciss.de/index.html

** (Tangential) Demo 4 - hey it's not a crasher anymore **

scala> val is = url.openStream
is: java.io.InputStream = sun.net.www.protocol.http.HttpURLConnection$HttpInputStream@5bc935cc

scala> is.

asInstanceOf available close isInstanceOf mark
markSupported read reset skip toString