Compile time NullPointerException

[nrinaudo]

I'm getting a compile time NPE when using export-hook.

I'm working on a minimal project that reproduces the issue, but it has so far proven frustrating. In the meantime, here's the repository that's causing the issue. Compiling the core project will cause the exception.

The problem seems to go away when I require sbt version 0.13.9 (as opposed to 0.13.7, where the issue occurs).

Here's the NPE's stack trace.
@milessabin pointed out here that it doesn't actually involve export-hook, but it only occurs when I add the @export.exports annotation.

java.lang.NullPointerException
    at xsbt.Dependency$ExtractDependenciesByMemberRefTraverser$$anonfun$1.isDefinedAt(Dependency.scala:142)
    at xsbt.Dependency$ExtractDependenciesByMemberRefTraverser$$anonfun$1.isDefinedAt(Dependency.scala:141)
    at xsbt.Dependency$CollectTypeTraverser.traverse(Dependency.scala:89)
    at xsbt.Dependency$ExtractDependenciesByMemberRefTraverser.traverse(Dependency.scala:144)
    at xsbt.Dependency$ExtractDependenciesByMemberRefTraverser.traverse(Dependency.scala:104)
    at scala.reflect.api.Trees$Traverser.traverseTypeAscription(Trees.scala:2478)
    at scala.reflect.internal.Trees$$anonfun$traverseMemberDef$1$1.apply$mcV$sp(Trees.scala:1214)
    at scala.reflect.api.Trees$Traverser.atOwner(Trees.scala:2507)
    at scala.reflect.internal.Trees$class.traverseMemberDef$1(Trees.scala:1203)
    at scala.reflect.internal.Trees$class.itraverse(Trees.scala:1328)
    at scala.reflect.internal.SymbolTable.itraverse(SymbolTable.scala:16)
    at scala.reflect.internal.SymbolTable.itraverse(SymbolTable.scala:16)
    at scala.reflect.api.Trees$Traverser.traverse(Trees.scala:2475)
    at xsbt.Dependency$ExtractDependenciesByMemberRefTraverser.traverse(Dependency.scala:153)
    at xsbt.Dependency$ExtractDependenciesByMemberRefTraverser.traverse(Dependency.scala:104)
    at scala.reflect.api.Trees$Traverser.traverseTrees(Trees.scala:2484)
    at xsbt.Dependency$ExtractDependenciesByMemberRefTraverser.traverse(Dependency.scala:148)
    at xsbt.Dependency$ExtractDependenciesByMemberRefTraverser.traverse(Dependency.scala:104)
    at scala.reflect.internal.Trees$$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$Traverser.traverse(Trees.scala:2475)
    at xsbt.Dependency$ExtractDependenciesByMemberRefTraverser.traverse(Dependency.scala:153)
    at xsbt.Dependency$ExtractDependenciesByMemberRefTraverser.traverse(Dependency.scala:104)
    at scala.reflect.api.Trees$Traverser.traverseTrees(Trees.scala:2484)
    at scala.reflect.internal.Trees$class.traverseComponents$1(Trees.scala:1284)
    at scala.reflect.internal.Trees$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$Traverser.traverse(Trees.scala:2475)
    at xsbt.Dependency$ExtractDependenciesByMemberRefTraverser.traverse(Dependency.scala:153)
    at xsbt.Dependency$ExtractDependenciesByMemberRefTraverser.traverse(Dependency.scala:150)
    at xsbt.Dependency$ExtractDependenciesByMemberRefTraverser.traverse(Dependency.scala:104)
    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$Traverser.traverse(Trees.scala:2475)
    at xsbt.Dependency$ExtractDependenciesByMemberRefTraverser.traverse(Dependency.scala:153)
    at xsbt.Dependency.xsbt$Dependency$$extractDependenciesByMemberRef(Dependency.scala:159)
    at xsbt.Dependency$DependencyPhase$$anonfun$run$2.apply(Dependency.scala:42)
    at xsbt.Dependency$DependencyPhase$$anonfun$run$2.apply(Dependency.scala:38)
    at scala.collection.Iterator$class.foreach(Iterator.scala:742)
    at scala.collection.AbstractIterator.foreach(Iterator.scala:1194)
    at xsbt.Dependency$DependencyPhase.run(Dependency.scala:38)
    at scala.tools.nsc.Global$Run.compileUnitsInternal(Global.scala:1501)
    at scala.tools.nsc.Global$Run.compileUnits(Global.scala:1486)
    at scala.tools.nsc.Global$Run.compileSources(Global.scala:1481)
    at scala.tools.nsc.Global$Run.compile(Global.scala:1582)
    at xsbt.CachedCompiler0.run(CompilerInterface.scala:116)
    at xsbt.CachedCompiler0.run(CompilerInterface.scala:95)
    at xsbt.CompilerInterface.run(CompilerInterface.scala:26)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at sbt.compiler.AnalyzingCompiler.call(AnalyzingCompiler.scala:101)
    at sbt.compiler.AnalyzingCompiler.compile(AnalyzingCompiler.scala:47)
    at sbt.compiler.AnalyzingCompiler.compile(AnalyzingCompiler.scala:41)
    at sbt.compiler.AggressiveCompile$$anonfun$3$$anonfun$compileScala$1$1.apply$mcV$sp(AggressiveCompile.scala:97)
    at sbt.compiler.AggressiveCompile$$anonfun$3$$anonfun$compileScala$1$1.apply(AggressiveCompile.scala:97)
    at sbt.compiler.AggressiveCompile$$anonfun$3$$anonfun$compileScala$1$1.apply(AggressiveCompile.scala:97)
    at sbt.compiler.AggressiveCompile.sbt$compiler$AggressiveCompile$$timed(AggressiveCompile.scala:162)
    at sbt.compiler.AggressiveCompile$$anonfun$3.compileScala$1(AggressiveCompile.scala:96)
    at sbt.compiler.AggressiveCompile$$anonfun$3.apply(AggressiveCompile.scala:139)
    at sbt.compiler.AggressiveCompile$$anonfun$3.apply(AggressiveCompile.scala:86)
    at sbt.inc.IncrementalCompile$$anonfun$doCompile$1.apply(Compile.scala:38)
    at sbt.inc.IncrementalCompile$$anonfun$doCompile$1.apply(Compile.scala:36)
    at sbt.inc.IncrementalCommon.cycle(IncrementalCommon.scala:31)
    at sbt.inc.Incremental$$anonfun$1.apply(Incremental.scala:39)
    at sbt.inc.Incremental$$anonfun$1.apply(Incremental.scala:38)
    at sbt.inc.Incremental$.manageClassfiles(Incremental.scala:66)
    at sbt.inc.Incremental$.compile(Incremental.scala:38)
    at sbt.inc.IncrementalCompile$.apply(Compile.scala:26)
    at sbt.compiler.AggressiveCompile.compile2(AggressiveCompile.scala:153)
    at sbt.compiler.AggressiveCompile.compile1(AggressiveCompile.scala:70)
    at sbt.compiler.AggressiveCompile.apply(AggressiveCompile.scala:45)
    at sbt.Compiler$.apply(Compiler.scala:74)
    at sbt.Compiler$.apply(Compiler.scala:65)
    at sbt.Defaults$.sbt$Defaults$$compileTaskImpl(Defaults.scala:789)
    at sbt.Defaults$$anonfun$compileTask$1.apply(Defaults.scala:781)
    at sbt.Defaults$$anonfun$compileTask$1.apply(Defaults.scala:781)
    at scala.Function1$$anonfun$compose$1.apply(Function1.scala:47)
    at sbt.$tilde$greater$$anonfun$$u2219$1.apply(TypeFunctions.scala:40)
    at sbt.std.Transform$$anon$4.work(System.scala:63)
    at sbt.Execute$$anonfun$submit$1$$anonfun$apply$1.apply(Execute.scala:226)
    at sbt.Execute$$anonfun$submit$1$$anonfun$apply$1.apply(Execute.scala:226)
    at sbt.ErrorHandling$.wideConvert(ErrorHandling.scala:17)
    at sbt.Execute.work(Execute.scala:235)
    at sbt.Execute$$anonfun$submit$1.apply(Execute.scala:226)
    at sbt.Execute$$anonfun$submit$1.apply(Execute.scala:226)
    at sbt.ConcurrentRestrictions$$anon$4$$anonfun$1.apply(ConcurrentRestrictions.scala:159)
    at sbt.CompletionService$$anon$2.call(CompletionService.scala:28)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
[error] (core/compile:compile) java.lang.NullPointerException

[milessabin]

I can confirm the NPE with SBT 0.13.7 and its absence with 0.13.9, so I'm going to read that as this being a now-fixed SBT issue.

If you're happy with that resolution we can close this.

[nrinaudo]

That seems like the right thing to do, yes.