How can I find the source file that causes a Scalac Compiler crash

Question

I am in the process of upgrading a large project to 2.10.4 to 2.11.4. I have gotten a compiler crash, is there anyway to display the name of source file that is causing the crash? I am able to get the full trace with ' last everitt/compile:compile'

I am going to revert to erasing large chunks of the project to binary search out the cause of the crash.

Here is the trace btw:

java.lang.NullPointerException
    at scala.tools.nsc.typechecker.NamesDefaults$class.baseFunBlock$1(NamesDefaults.scala:130)
    at scala.tools.nsc.typechecker.NamesDefaults$class.transformNamedApplication(NamesDefaults.scala:375)
    at scala.tools.nsc.Global$$anon$1.transformNamedApplication(Global.scala:450)
    at scala.tools.nsc.typechecker.NamesDefaults$class.transformNamedApplication(NamesDefaults.scala:326)
    at scala.tools.nsc.Global$$anon$1.transformNamedApplication(Global.scala:450)
    at scala.tools.nsc.typechecker.Typers$Typer.tryNamesDefaults$1(Typers.scala:3298)
    at scala.tools.nsc.typechecker.Typers$Typer.doTypedApply(Typers.scala:3367)
    at scala.tools.nsc.typechecker.Typers$Typer.tryNamesDefaults$1(Typers.scala:3353)
    at scala.tools.nsc.typechecker.Typers$Typer.doTypedApply(Typers.scala:3367)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$tryTypedApply$1$1.apply(Typers.scala:4404)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$tryTypedApply$1$1.apply(Typers.scala:4404)
    at scala.tools.nsc.typechecker.Typers$Typer.silent(Typers.scala:689)
    at scala.tools.nsc.typechecker.Typers$Typer.tryTypedApply$1(Typers.scala:4404)
    at scala.tools.nsc.typechecker.Typers$Typer.normalTypedApply$1(Typers.scala:4449)
    at scala.tools.nsc.typechecker.Typers$Typer.typedApply$1(Typers.scala:4484)
    at scala.tools.nsc.typechecker.Typers$Typer.typedInAnyMode$1(Typers.scala:5242)
    at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5259)
    at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5295)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5322)
    at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5269)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5273)
    at scala.tools.nsc.typechecker.Typers$Typer.typedArg(Typers.scala:3094)
    at scala.tools.nsc.typechecker.PatternTypers$PatternTyper$class.typedArgWithFormal$1(PatternTypers.scala:112)
    at scala.tools.nsc.typechecker.PatternTypers$PatternTyper$$anonfun$2.apply(PatternTypers.scala:115)
    at scala.tools.nsc.typechecker.PatternTypers$PatternTyper$$anonfun$2.apply(PatternTypers.scala:115)
    at scala.runtime.Tuple2Zipped$$anonfun$map$extension$1.apply(Tuple2Zipped.scala:42)
    at scala.runtime.Tuple2Zipped$$anonfun$map$extension$1.apply(Tuple2Zipped.scala:40)
    at scala.collection.immutable.List.foreach(List.scala:381)
    at scala.runtime.Tuple2Zipped$.map$extension(Tuple2Zipped.scala:40)
    at scala.tools.nsc.typechecker.PatternTypers$PatternTyper$class.typedArgsForFormals(PatternTypers.scala:115)
    at scala.tools.nsc.typechecker.Typers$Typer.typedArgsForFormals(Typers.scala:107)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$handleMonomorphicCall$1(Typers.scala:3384)
    at scala.tools.nsc.typechecker.Typers$Typer.doTypedApply(Typers.scala:3409)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$tryTypedApply$1$1.apply(Typers.scala:4404)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$tryTypedApply$1$1.apply(Typers.scala:4404)
    at scala.tools.nsc.typechecker.Typers$Typer.silent(Typers.scala:676)
    at scala.tools.nsc.typechecker.Typers$Typer.tryTypedApply$1(Typers.scala:4404)
    at scala.tools.nsc.typechecker.Typers$Typer.normalTypedApply$1(Typers.scala:4449)
    at scala.tools.nsc.typechecker.Typers$Typer.typedApply$1(Typers.scala:4484)
    at scala.tools.nsc.typechecker.Typers$Typer.typedInAnyMode$1(Typers.scala:5242)
    at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5259)
    at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5295)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5322)
    at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5269)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5273)
    at scala.tools.nsc.typechecker.Typers$Typer.typedAssign$1(Typers.scala:4136)
    at scala.tools.nsc.typechecker.Typers$Typer.typedOutsidePatternMode$1(Typers.scala:5223)
    at scala.tools.nsc.typechecker.Typers$Typer.typedInAnyMode$1(Typers.scala:5252)
    at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5259)
    at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5295)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5322)
    at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5269)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5273)
    at scala.tools.nsc.typechecker.Typers$Typer.typedBlock(Typers.scala:2341)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$typedOutsidePatternMode$1$1.apply(Typers.scala:5217)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$typedOutsidePatternMode$1$1.apply(Typers.scala:5217)
    at scala.tools.nsc.typechecker.Typers$Typer.typedOutsidePatternMode$1(Typers.scala:5216)
    at scala.tools.nsc.typechecker.Typers$Typer.typedInAnyMode$1(Typers.scala:5252)
    at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5259)
    at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5295)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5322)
    at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5269)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5273)
    at scala.tools.nsc.typechecker.Typers$Typer.transformedOrTyped(Typers.scala:5504)
    at scala.tools.nsc.typechecker.Typers$Typer.typedDefDef(Typers.scala:2167)
    at scala.tools.nsc.typechecker.Typers$Typer.typedMemberDef$1(Typers.scala:5207)
    at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5258)
    at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5295)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5322)
    at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5269)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5273)
    at scala.tools.nsc.typechecker.Typers$Typer.typedByValueExpr(Typers.scala:5351)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedStat$1(Typers.scala:2977)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$60.apply(Typers.scala:3081)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$60.apply(Typers.scala:3081)
    at scala.collection.immutable.List.loop$1(List.scala:172)
    at scala.collection.immutable.List.mapConserve(List.scala:188)
    at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:3081)
    at scala.tools.nsc.typechecker.Typers$Typer.typedTemplate(Typers.scala:1880)
    at scala.tools.nsc.typechecker.Typers$Typer.typedClassDef(Typers.scala:1721)
    at scala.tools.nsc.typechecker.Typers$Typer.typedMemberDef$1(Typers.scala:5208)
    at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5258)
    at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5295)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5322)
    at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5269)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5273)
    at scala.tools.nsc.typechecker.Typers$Typer.typedByValueExpr(Typers.scala:5351)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedStat$1(Typers.scala:2977)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$60.apply(Typers.scala:3081)
    at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$60.apply(Typers.scala:3081)
    at scala.collection.immutable.List.loop$1(List.scala:172)
    at scala.collection.immutable.List.mapConserve(List.scala:188)
    at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:3081)
    at scala.tools.nsc.typechecker.Typers$Typer.typedPackageDef$1(Typers.scala:4918)
    at scala.tools.nsc.typechecker.Typers$Typer.typedMemberDef$1(Typers.scala:5211)
    at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5258)
    at scala.tools.nsc.typechecker.Typers$Typer.runTyper$1(Typers.scala:5295)
    at scala.tools.nsc.typechecker.Typers$Typer.scala$tools$nsc$typechecker$Typers$Typer$$typedInternal(Typers.scala:5322)
    at scala.tools.nsc.typechecker.Typers$Typer.body$2(Typers.scala:5269)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5273)
    at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5347)
    at scala.tools.nsc.typechecker.Analyzer$typerFactory$$anon$3.apply(Analyzer.scala:102)
    at scala.tools.nsc.Global$GlobalPhase$$anonfun$applyPhase$1.apply$mcV$sp(Global.scala:428)
    at scala.tools.nsc.Global$GlobalPhase.withCurrentUnit(Global.scala:419)
    at scala.tools.nsc.Global$GlobalPhase.applyPhase(Global.scala:428)
    at scala.tools.nsc.typechecker.Analyzer$typerFactory$$anon$3$$anonfun$run$1.apply(Analyzer.scala:94)
    at scala.tools.nsc.typechecker.Analyzer$typerFactory$$anon$3$$anonfun$run$1.apply(Analyzer.scala:93)
    at scala.collection.Iterator$class.foreach(Iterator.scala:743)
    at scala.collection.AbstractIterator.foreach(Iterator.scala:1195)
    at scala.tools.nsc.typechecker.Analyzer$typerFactory$$anon$3.run(Analyzer.scala:93)
    at scala.tools.nsc.Global$Run.compileUnitsInternal(Global.scala:1338)
    at scala.tools.nsc.Global$Run.compileUnits(Global.scala:1325)
    at scala.tools.nsc.Global$Run.compileSources(Global.scala:1320)
    at scala.tools.nsc.Global$Run.compile(Global.scala:1418)
    at xsbt.CachedCompiler0.run(CompilerInterface.scala:116)
    at xsbt.CachedCompiler0.run(CompilerInterface.scala:95)
    at xsbt.CompilerInterface.run(CompilerInterface.scala:26)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at sbt.compiler.AnalyzingCompiler.call(AnalyzingCompiler.scala:101)
    at sbt.compiler.AnalyzingCompiler.compile(AnalyzingCompiler.scala:47)
    at sbt.compiler.AnalyzingCompiler.compile(AnalyzingCompiler.scala:41)
    at sbt.compiler.AggressiveCompile$$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:777)
    at sbt.Defaults$$anonfun$compileTask$1.apply(Defaults.scala:769)
    at sbt.Defaults$$anonfun$compileTask$1.apply(Defaults.scala:769)
    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$2.call(CompletionService.scala:28)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)

Edit: After erasing and commenting out lots of files I simplified it to this:

case class A(x: String)
case class B(a: A, y: String)
class C(var b: B) {
  def a = b.a
  b.copy(a = a.copy())
}

Edit2: Best I can tell is that there isn't a good option for this, I am going to move on, I filed a bug report for this issue (SI-9035). If anyone knows of the option / way to do this please post an answer! In the meantime I will just continue to use the method I have been using since 2.6: erase files and comment out lines until I get it down to a minimum example and submit a bug report. Thanks for the ideas.

Answer 1

In this case -verbose indicates it's done with phase packageobjects, and -Xshow-phases says typer is next. (Parser reports what it just parsed.)

-Ytyper-debug emits reams of generally inscrutable output, but shows what is undergoing typechecking.

That information can at least help your next search or gitter question.

Something like:

|    |    |-- b.copy(a = a.copy()) EXPRmode (site: method f in C) 
|    |    |    |-- b.copy BYVALmode-EXPRmode-FUNmode-POLYmode (silent: method f in C) 
|    |    |    |    |-- b EXPRmode-POLYmode-QUALmode (silent: method f in C) 
|    |    |    |    |    \-> nope.B
|    |    |    |    \-> (a: nope.A, y: String)nope.B
|    |    |    |-- qual$1 EXPRmode-POLYmode-QUALmode (silent: method f in C) 
|    |    |    |    \-> qual$1.type (with underlying type nope.B)
|    |    |    |-- (a: nope.A, y: String)nope.B EXPRmode-FUNmode-POLYmode-TAPPmode (silent: method f in C) 
|    |    |    |    \-> (a: nope.A, y: String)nope.B
|    |    |    |-- a = a.copy() : pt=nope.A EXPRmode (silent: method f in C) 
|    |    |    |    |-- a EXPRmode-LHSmode (silent: method f in C) 
|    |    |    |    |    \-> nope.A
|    |    |    |    |-- C.this.a_$eq(a.copy()) : pt=nope.A EXPRmode (silent: method f in C) 
|    |    |    |    |    |-- C.this.a_$eq BYVALmode-EXPRmode-FUNmode-POLYmode (silent: method f in C) 
|    |    |    |    |    |    \-> <error>
|    |    |    |    |    |-- a.copy() : pt=<error> EXPRmode (silent: method f in C) 
|    |    |    |    |    |    |-- a.copy BYVALmode-EXPRmode-FUNmode-POLYmode (silent: method f in C) 
|    |    |    |    |    |    |    |-- a EXPRmode-POLYmode-QUALmode (silent: method f in C) 
|    |    |    |    |    |    |    |    \-> nope.A
|    |    |    |    |    |    |    \-> (x: String)nope.A
|    |    |    |    |    |    |-- qual$2 EXPRmode-POLYmode-QUALmode (silent: method f in C) 
|    |    |    |    |    |    |    \-> qual$2.type (with underlying type nope.A)
|    |    |    |    |    |    |-- (x: String)nope.A EXPRmode-FUNmode-POLYmode-TAPPmode (silent: method f in C) 
|    |    |    |    |    |    |    \-> (x: String)nope.A
|    |    |    |    |    |    \-> nope.A
|    |    |    |    |    \-> <error>
|    |    |    |    \-> <error>
error: java.lang.NullPointerException
    at scala.tools.nsc.typechecker.Typers$Typer.noExpectedType$1(Typers.scala:3464)

might lead you to search for any bugs with "named arguments", such as this open bug; not your crasher, but similar players.

When the compiler "aborts", it offers more useful information than when it full-on crashes.