Regression: exception while transforming attempt of class class dotty.tools.dotc.ast.Trees$Ident

[olafurpg]

See stacktrace while compiling scalatest with Dotty at commit 4b33e36 from April 11th: https://travis-ci.org/lampepfl/dotty-community-build/jobs/221252016#L7457

The build was green at commit 0bd7821 on April 10th: https://travis-ci.org/lampepfl/dotty-community-build/jobs/220858741#L261

[OlivierBlanvillain]

It's a bit tricky to minimise scalatest issues, the best approach I can see is to git bisect from the dotty repo:

export COMPILERVERSION=0.1.1-SNAPSHOT
sbt publish-local && (cd ~/workspace/scalatest;  sbt ";clean ;compile")
# dotty doesn't compile     → git bisect skip
# scalatest doesn't compile → git bisect bad
# scalatest compiles        → git bisect good

Given that each step takes about ~5 minutes at full CPU, I think this really needs to be automated. Without a way to pinpoint a single commit/PR, it's really to even get started on such issues. But at the same time, if we keep things in a failing states, it defeats the purpose of the community build.

[smarter]

I've opened #2246 to track one possible cause of the issue.

[OlivierBlanvillain]

I think the issue comes from this PR: #2128. Unfortunately many commits do not compile, so I could not reduce it to something small (git bisect says something went wrong between d5c1e6d and 87608bd).

[smarter]

The problem actually comes from PR #2216, minimization:

class Foo(x: Any => Any)

class Test {
  def foo(param: Int) = {
    class Hi extends Foo(_ => param)
  }
}

Exception in thread "main" java.lang.IllegalArgumentException: Could not find proxy for param: Int in List(val param, method foo, class Test, module class <empty>, module class <root>), encl = method $anonfun, owners = method $anonfun, constructor Hi, class Hi, method foo, class Test, package <empty>, package <root>; enclosures = method $anonfun, class Test, package <empty>, package <root>
        at dotty.tools.dotc.transform.LambdaLift$LambdaLifter.searchIn$1(LambdaLift.scala:425)
        at dotty.tools.dotc.transform.LambdaLift$LambdaLifter.proxy(LambdaLift.scala:438)
        at dotty.tools.dotc.transform.LambdaLift$LambdaLifter.dotty$tools$dotc$transform$LambdaLift$LambdaLifter$$proxyRef(LambdaLift.scala:456)
        at dotty.tools.dotc.transform.LambdaLift$LambdaLifter.transformIdent(LambdaLift.scala:510)

[olafurpg]

I am still able to reproduce this error with dotty version 0.1.1-bin-20170427-fa13f8d-NIGHTLY

Here is a log of the stack trace crash-log.zip The output is truncated by Travis https://travis-ci.org/dotty-staging/scalatest/builds/226833950

[smarter]

@olafurpg This should be fixed once #2282 is merged.

[odersky]

@olafurpg #2282 was just merged. Can you check again? Thanks!

[olafurpg]

I can confirm that the error message is no longer "java.lang.IllegalArgumentException: Could not find proxy for attempt:". We can close this issue.

There is now a new error

 [error] (compile:compileIncremental) java.lang.NoSuchMethodError: dotty.tools.dotc.reporting.UniqueMessagePositions.dotty$tools$dotc$reporting$UniqueMessagePositions$$initial$positions()Lscala/collection/mutable/HashMap;

I thought it was caused by an outdated dotty bridge but I'm on sbt 0.13.15 and using sbt-dotty 0.1.0-RC3.