Scala – Why does sbt compile fail with StackOverflowError

I am working on a Scala project that has been in existence for a few years but is new to me. My task is to upgrade it from Scala 2.9.3 to 2.11.7, along with its dependencies. I have gotten past the errors and warnings, but I cannot get the project to compile successfully in SBT. I always get a StackOverflowError in pretty much the same place. The stacktrace looks like this, but details vary with the Xss setting (currently 4M, but have tried as high as 24M):

java.lang.StackOverflowError
at scala.tools.nsc.transform.Erasure$Eraser.typed1(Erasure.scala:698)
at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5395)
at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5422)
at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5369)
at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5373)
at scala.tools.nsc.typechecker.Typers$Typer.typedQualifier(Typers.scala:5471)
at scala.tools.nsc.typechecker.Typers$Typer.typedQualifier(Typers.scala:5479)
at scala.tools.nsc.transform.Erasure$Eraser.adaptMember(Erasure.scala:644)
at scala.tools.nsc.transform.Erasure$Eraser.typed1(Erasure.scala:698)
at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5395)
at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5422)

SBT_OPTS looks like this:

-Xmx2G -Xss4M -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled

I can 'make' the project successfully in Intellij, and others can pull my changes from GitHub and compile the project in sbt, so the issue seems to be local to my machine (a recent quad-core Macbook Pro with 16GB RAM). Other Scala/sbt projects compile successfully for me on this machine.

Here are other relevant details:

Scala version: 2.11.7
Java version: java version "1.8.0_66" (build 1.8.0_66-b17)
sbt version: 0.13.7 (have also tried 0.13.9)

I have completely rebuilt the ivy2 cache and cleared the lib_managed directory. The version of the scala-compiler.jar is the same as is used on at least one machine that can 'sbt compile' the code successfully. I did a clean reinstall of sbt (via brew remove sbt, manual removal of ~/.sbt directory, then brew install sbt).

I have not tried to isolate the line of source code being compiled when the error occurs. I have assumed it would be more productive to look for a configuration issue or dependency conflict somewhere.

Any suggestions for further troubleshooting will be appreciated.

[Added…] It may be helpful to add that, as an experiment, I downloaded the Scala language source code from https://github.com/scala/scala and got the following very similar error trying to sbt compile it:

java.lang.StackOverflowError
at scala.tools.nsc.transform.ExplicitOuter$OuterPathTransformer.outerValue(ExplicitOuter.scala:229)
at scala.tools.nsc.transform.ExplicitOuter$ExplicitOuterTransformer.transform(ExplicitOuter.scala:441)
at scala.tools.nsc.transform.ExplicitOuter$ExplicitOuterTransformer.transform(ExplicitOuter.scala:352)
at scala.reflect.internal.Trees$class.itransform(Trees.scala:1345)
at scala.reflect.internal.SymbolTable.itransform(SymbolTable.scala:16)
at scala.reflect.internal.SymbolTable.itransform(SymbolTable.scala:16)
at scala.reflect.api.Trees$Transformer.transform(Trees.scala:2555)
at scala.tools.nsc.transform.TypingTransformers$TypingTransformer.transform(TypingTransformers.scala:44)
at scala.tools.nsc.transform.ExplicitOuter$OuterPathTransformer.scala$reflect$internal$Trees$UnderConstructionTransformer$$super$transform(ExplicitOuter.scala:219)
at scala.reflect.internal.Trees$UnderConstructionTransformer$class.transform(Trees.scala:1693)
at scala.tools.nsc.transform.ExplicitOuter$OuterPathTransformer.transform(ExplicitOuter.scala:291)
at scala.tools.nsc.transform.ExplicitOuter$ExplicitOuterTransformer.transform(ExplicitOuter.scala:459)
at scala.tools.nsc.transform.ExplicitOuter$ExplicitOuterTransformer.transform(ExplicitOuter.scala:352)
at scala.reflect.internal.Trees$class.itransform(Trees.scala:1347)
at scala.reflect.internal.SymbolTable.itransform(SymbolTable.scala:16)
at scala.reflect.internal.SymbolTable.itransform(SymbolTable.scala:16)
at scala.reflect.api.Trees$Transformer.transform(Trees.scala:2555)

Here is something interesting. From this post I found out about launching sbt with a -d flag for debugging info. Got the following output:

Kevins-MacBook-Pro:scala kdoherty$ sbt -d
[process_args] java_version = '1.8.0_66'
# Executing command line:
java
-Xmx2G
-Xss4M
-XX:+UseConcMarkSweepGC
-XX:+CMSClassUnloadingEnabled
-Xmx384m
-Xss512k
-XX:+UseCompressedOops
-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5005
-jar
/usr/local/Cellar/sbt/0.13.9/libexec/sbt-launch.jar

So somewhere my SBT_OPTS settings are being overridden (by defaults, I guess). Now I need to find where those defaults are coming from.