file:dV9sWCCIWr5QyoacwqEsg8

package bug

trait A

object Bar { implicit def foo[T <: A, U](implicit ev: T <:< Comparable[U], ev2: T <:< U): Ordering[T] = (a: T, b: T) => a.compareTo(b) }

gives the stacktrace attached. This is using Scala IDE 4.4.1.

I can't reproduce with the given code example on the latest nightly. Do you have the time to check if the problem still happens with the latest nightly?

I downloaded the latest nightly, and the problem is still there. I'm not sure if this is relevant, but I have the macroparadise compiler plugin installed, and it has been causing other crashes in the presentation compiler (which I plan to submit a separate bug for if I can narrow it down).

I did not make this file in an isolated project, but rather as part of a bigger project. Do you have any suggestions for narrowing down the source of this crash for me? Does the stack trace give you any indication of what the problem might be?

eclipse.buildId=4.5.2.M20160212-1500
java.version=1.8.0_31
java.vendor=Oracle Corporation
BootLoader constants: OS=macosx, ARCH=x86_64, WS=cocoa, NL=en_US
Framework arguments: -product org.eclipse.epp.package.java.product -product org.eclipse.epp.package.java.product -keyring /Users/adpauls/.eclipse_keyring -showlocation
Command-line arguments: -os macosx -ws cocoa -arch x86_64 -product org.eclipse.epp.package.java.product -data file:/Users/adpauls/sm/EclipseProjects/ -product org.eclipse.epp.package.java.product -keyring /Users/adpauls/.eclipse_keyring -showlocation

org.scala-ide.sdt.core
Error
Sun Sep 04 01:08:30 PDT 2016
Unexptected error - most likely due to an illegal position

java.lang.AssertionError: assertion failed: bad position: [139:137]
at scala.reflect.internal.util.Position$.validate(Position.scala:34)
at scala.reflect.internal.util.Position$.range(Position.scala:51)
at scala.reflect.internal.util.InternalPositionImpl$class.copyRange(Position.scala:205)
at scala.reflect.internal.util.InternalPositionImpl$class.withStart(Position.scala:124)
at scala.reflect.internal.util.Position.withStart(Position.scala:12)
at scala.tools.refactoring.common.EnrichedTrees$TreeMethodsForPositions.namePosition(EnrichedTrees.scala:196)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SafeSymbol$class.safeSymbol(SafeSymbol.scala:154)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SymbolClassification.safeSymbol(SymbolClassification.scala:34)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SymbolClassification.org$scalaide$core$internal$decorators$semantichighlighting$classifier$SymbolClassification$$findSymbolInfo$1(SymbolClassification.scala:93)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SymbolClassification$$anon$1.traverse(SymbolClassification.scala:105)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SymbolClassification$$anon$1.traverse(SymbolClassification.scala:99)
at scala.reflect.api.Trees$Traverser.traverseTrees(Trees.scala:2484)
at scala.reflect.internal.Trees$class.traverseComponents$1(Trees.scala:1234)
at scala.reflect.internal.Trees$class.itraverse(Trees.scala:1330)
at scala.reflect.internal.SymbolTable.itraverse(SymbolTable.scala:16)
at scala.reflect.internal.SymbolTable.itraverse(SymbolTable.scala:16)
at scala.reflect.api.Trees$Traverser.traverse(Trees.scala:2475)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SymbolClassification$$anon$1.traverse(SymbolClassification.scala:108)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SymbolClassification$$anon$1.traverse(SymbolClassification.scala:99)
at scala.reflect.internal.Trees$$anonfun$traverseMemberDef$1$1.apply$mcV$sp(Trees.scala:1215)
at scala.reflect.api.Trees$Traverser.atOwner(Trees.scala:2507)
at scala.reflect.internal.Trees$class.traverseMemberDef$1(Trees.scala:1203)
at scala.reflect.internal.Trees$class.itraverse(Trees.scala:1328)
at scala.reflect.internal.SymbolTable.itraverse(SymbolTable.scala:16)
at scala.reflect.internal.SymbolTable.itraverse(SymbolTable.scala:16)
at scala.reflect.api.Trees$Traverser.traverse(Trees.scala:2475)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SymbolClassification$$anon$1.traverse(SymbolClassification.scala:108)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SymbolClassification$$anon$1.traverse(SymbolClassification.scala:99)
at scala.reflect.api.Trees$Traverser$$anonfun$traverseStats$1$$anonfun$apply$1.apply$mcV$sp(Trees.scala:2498)
at scala.reflect.api.Trees$Traverser.atOwner(Trees.scala:2507)
at scala.reflect.api.Trees$Traverser.traverseStats(Trees.scala:2497)
at scala.reflect.internal.Trees$class.traverseComponents$1(Trees.scala:1232)
at scala.reflect.internal.Trees$class.itraverse(Trees.scala:1330)
at scala.reflect.internal.SymbolTable.itraverse(SymbolTable.scala:16)
at scala.reflect.internal.SymbolTable.itraverse(SymbolTable.scala:16)
at scala.reflect.api.Trees$Traverser.traverse(Trees.scala:2475)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SymbolClassification$$anon$1.traverse(SymbolClassification.scala:108)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SymbolClassification$$anon$1.traverse(SymbolClassification.scala:99)
at scala.reflect.internal.Trees$$anonfun$traverseMemberDef$1$1.apply$mcV$sp(Trees.scala:1208)
at scala.reflect.api.Trees$Traverser.atOwner(Trees.scala:2507)
at scala.reflect.internal.Trees$class.traverseMemberDef$1(Trees.scala:1203)
at scala.reflect.internal.Trees$class.itraverse(Trees.scala:1327)
at scala.reflect.internal.SymbolTable.itraverse(SymbolTable.scala:16)
at scala.reflect.internal.SymbolTable.itraverse(SymbolTable.scala:16)
at scala.reflect.api.Trees$Traverser.traverse(Trees.scala:2475)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SymbolClassification$$anon$1.traverse(SymbolClassification.scala:108)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SymbolClassification$$anon$1.traverse(SymbolClassification.scala:99)
at scala.reflect.api.Trees$Traverser$$anonfun$traverseStats$1$$anonfun$apply$1.apply$mcV$sp(Trees.scala:2498)
at scala.reflect.api.Trees$Traverser.atOwner(Trees.scala:2507)
at scala.reflect.api.Trees$Traverser.traverseStats(Trees.scala:2497)
at scala.reflect.internal.Trees$class.itraverse(Trees.scala:1326)
at scala.reflect.internal.SymbolTable.itraverse(SymbolTable.scala:16)
at scala.reflect.internal.SymbolTable.itraverse(SymbolTable.scala:16)
at scala.reflect.api.Trees$Traverser.traverse(Trees.scala:2475)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SymbolClassification$$anon$1.traverse(SymbolClassification.scala:108)
at org.scalaide.core.internal.decorators.semantichighlighting.classifier.SymbolClassification.classifySymbols(SymbolClassification.scala:110)
at org.scalaide.ui.internal.editor.decorators.semantichighlighting.Presenter$SemanticHighlightingJob$$anonfun$performSemanticHighlighting$1$$anonfun$apply$1.apply(Presenter.scala:123)
at org.scalaide.ui.internal.editor.decorators.semantichighlighting.Presenter$SemanticHighlightingJob$$anonfun$performSemanticHighlighting$1$$anonfun$apply$1.apply(Presenter.scala:119)
at org.scalaide.core.compiler.InteractiveCompilationUnit$$anonfun$withSourceFile$1.apply(InteractiveCompilationUnit.scala:201)
at org.scalaide.core.compiler.InteractiveCompilationUnit$$anonfun$withSourceFile$1.apply(InteractiveCompilationUnit.scala:201)
at org.scalaide.core.internal.compiler.PresentationCompilerProxy$$anonfun$internal$1.apply(PresentationCompilerProxy.scala:101)
at org.scalaide.core.internal.compiler.PresentationCompilerProxy$$anonfun$internal$1.apply(PresentationCompilerProxy.scala:100)
at scala.Option.flatMap(Option.scala:171)
at org.scalaide.core.internal.compiler.PresentationCompilerProxy.internal(PresentationCompilerProxy.scala:100)
at org.scalaide.core.internal.compiler.PresentationCompilerProxy.apply(PresentationCompilerProxy.scala:58)
at org.scalaide.core.compiler.InteractiveCompilationUnit$class.withSourceFile(InteractiveCompilationUnit.scala:201)
at org.scalaide.core.internal.jdt.model.ScalaSourceFile.withSourceFile(ScalaSourceFile.scala:71)
at org.scalaide.ui.internal.editor.decorators.semantichighlighting.Presenter$SemanticHighlightingJob$$anonfun$performSemanticHighlighting$1.apply(Presenter.scala:119)
at org.scalaide.ui.internal.editor.decorators.semantichighlighting.Presenter$SemanticHighlightingJob$$anonfun$performSemanticHighlighting$1.apply(Presenter.scala:119)
at scala.Option.flatMap(Option.scala:171)
at org.scalaide.ui.internal.editor.decorators.semantichighlighting.Presenter$SemanticHighlightingJob.performSemanticHighlighting(Presenter.scala:119)
at org.scalaide.ui.internal.editor.decorators.semantichighlighting.Presenter$SemanticHighlightingJob.run(Presenter.scala:115)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)

I reduced it a little further:

object Bar { def foo[T <: Comparable[T]]: Ordering[T] = (a: T, b: T) => a.compareTo(b) }

Still causes the issue. However, this does not:

object Bar { def foo[T <: Comparable[T]]: Ordering[T] = new Ordering[T] { def compare(a: T, b: T) = a.compareTo(b) } }

Your code examples do not compile. Do you have an implicit conversion lying around somewhere from (T,T) => Int to Ordering[T] or do you also get compilation errors?

Beside from that the problem is that we create a position internally which is not valid. I do not understand why the position can be invalid just by looking at our code though.

I have -Xexperimental on. This is just a SAM conversion right?

EDIT: I verified that it compiles on my machine using sbt. This program:

package bar

object Bar {
  def foo[T <: Comparable[T]]: Ordering[T] = (a: T, b: T) => a.compareTo(b)
  def main(args: Array[String]): Unit = {
    val data = IndexedSeq("1","3","2")
    println(data.sorted(foo[String]))
  }
}

Ran just fine:

sbt "runMain bug.Bar"
.....
[info] Running bug.Bar 
[info] Vector(1, 2, 3)
[success] Total time: 7 s, completed Sep 4, 2016 9:02:59 AM

Ok, with -Xexperimental enabled I can reproduce the issue. The issue now actually makes sense. I guess the transformation of the SAM converter creates some invalid positions, which is not very surprising given that it is an experimental feature.