3.7 regression: unhandled exception while running MegaPhase - map extension for (Int, Int) #22727

OndrejSpanel · 2025-03-05T20:27:47Z

Compiler version

3.7.0-RC1-bin-20250228-e592b37-NIGHTLY

The same code works fine in 3.6.3 or 3.6.4-RC2.

Minimized code

object Main {
  type IXY = (Int, Int)

  extension (xy: IXY) {
    def map(f: Int => Int): (Int, Int) = (f(xy._1), f(xy._2))
  }

  def main(args: Array[String]): Unit = {
    val a = (0, 1)
    println(a)
  }
}

Output (click arrow to expand)

scala: 
  unhandled exception while running MegaPhase{crossVersionChecks, firstTransform, checkReentrant, elimPackagePrefixes, cookComments, checkLoopingImplicits, betaReduce, inlineVals, expandSAMs, elimRepeated, refchecks, dropForMap} on C:\Dev\Sandbox\src\main\scala\Main.scala

  An unhandled exception was thrown in the compiler.
  Please file a crash report here:
  https://github.com/scala/scala3/issues/new/choose
  For non-enriched exceptions, compile with -Xno-enrich-error-messages.


     while compiling: C:\Dev\Sandbox\src\main\scala\Main.scala
        during phase: MegaPhase{crossVersionChecks, firstTransform, checkReentrant, elimPackagePrefixes, cookComments, checkLoopingImplicits, betaReduce, inlineVals, expandSAMs, elimRepeated, refchecks, dropForMap}
                mode: Mode(ImplicitsEnabled)
     library version: version 2.13.16
    compiler version: version 3.7.0-RC1-bin-20250228-e592b37-NIGHTLY-git-e592b37

     while compiling: C:\Dev\Sandbox\src\main\scala\Main.scala
        during phase: MegaPhase{crossVersionChecks, firstTransform, checkReentrant, elimPackagePrefixes, cookComments, checkLoopingImplicits, betaReduce, inlineVals, expandSAMs, elimRepeated, refchecks, dropForMap}
                mode: Mode(ImplicitsEnabled)
     library version: version 2.13.16
    compiler version: version 3.7.0-RC1-bin-20250228-e592b37-NIGHTLY-git-e592b37
            settings: -Werror true -Wunused List(imports) -classpath C:\Dev\Sandbox\target\scala-3.7.0-RC1-bin-20250228-e592b37-NIGHTLY\classes;C:\Users\Ondra\AppData\Local\Coursier\Cache\v1\https\repo1.maven.org\maven2\org\scala-lang\scala3-library_3\3.7.0-RC1-bin-20250228-e592b37-NIGHTLY\scala3-library_3-3.7.0-RC1-bin-20250228-e592b37-NIGHTLY.jar;C:\Users\Ondra\AppData\Local\Coursier\Cache\v1\https\repo1.maven.org\maven2\org\scala-lang\scala-library\2.13.16\scala-library-2.13.16.jar -d C:\Dev\Sandbox\target\scala-3.7.0-RC1-bin-20250228-e592b37-NIGHTLY\classes

[error] ## Exception when compiling 1 sources to C:\Dev\Sandbox\target\scala-3.7.0-RC1-bin-20250228-e592b37-NIGHTLY\classes
[error] java.lang.AssertionError: assertion failed: TypeAlias(AppliedType(TypeRef(ThisType(TypeRef(NoPrefix,module class scala)),class Tuple2),List(TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),class Int), TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),class Int))))
[error] scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
[error] dotty.tools.dotc.core.Types$TypeBounds.<init>(Types.scala:5555)
[error] dotty.tools.dotc.core.Types$RealTypeBounds.<init>(Types.scala:5631)
[error] dotty.tools.dotc.core.Types$TypeBounds$.apply(Types.scala:5672)
[error] dotty.tools.dotc.core.Types$ApproximatingTypeMap.rangeToBounds(Types.scala:6376)
[error] dotty.tools.dotc.core.Types$ApproximatingTypeMap.derivedAppliedType$$anonfun$2(Types.scala:6516)
[error] scala.collection.immutable.List.map(List.scala:247)
[error] dotty.tools.dotc.core.Types$ApproximatingTypeMap.derivedAppliedType(Types.scala:6516)
[error] dotty.tools.dotc.core.Types$TypeMap.mapOver(Types.scala:6203)
[error] dotty.tools.dotc.core.TypeOps$AsSeenFromMap.apply(TypeOps.scala:111)
[error] dotty.tools.dotc.core.Types$TypeMap.mapOverLambda(Types.scala:6160)
[error] dotty.tools.dotc.core.TypeOps$AsSeenFromMap.apply(TypeOps.scala:105)
[error] dotty.tools.dotc.core.Types$TypeMap.mapOverLambda(Types.scala:6160)
[error] dotty.tools.dotc.core.TypeOps$AsSeenFromMap.apply(TypeOps.scala:105)
[error] dotty.tools.dotc.core.TypeOps$.asSeenFrom(TypeOps.scala:55)
[error] dotty.tools.dotc.core.Types$Type.asSeenFrom(Types.scala:1113)
[error] dotty.tools.dotc.core.Denotations$SingleDenotation.derived$1(Denotations.scala:1107)
[error] dotty.tools.dotc.core.Denotations$SingleDenotation.computeAsSeenFrom(Denotations.scala:1134)
[error] dotty.tools.dotc.core.Denotations$SingleDenotation.computeAsSeenFrom(Denotations.scala:1087)
[error] dotty.tools.dotc.core.Denotations$PreDenotation.asSeenFrom(Denotations.scala:137)
[error] dotty.tools.dotc.core.SymDenotations$ClassDenotation.findMember(SymDenotations.scala:2195)
[error] dotty.tools.dotc.core.Types$Type.go$1(Types.scala:778)
[error] dotty.tools.dotc.core.Types$Type.findMember(Types.scala:959)
[error] dotty.tools.dotc.core.Types$Type.memberBasedOnFlags(Types.scala:751)
[error] dotty.tools.dotc.core.Types$Type.nonPrivateMember(Types.scala:741)
[error] dotty.tools.dotc.typer.RefChecks$.hidden$1(RefChecks.scala:1177)
[error] dotty.tools.dotc.typer.RefChecks$.checkExtensionMethods(RefChecks.scala:1203)
[error] dotty.tools.dotc.typer.RefChecks.transformDefDef(RefChecks.scala:1357)
[error] dotty.tools.dotc.typer.RefChecks.transformDefDef(RefChecks.scala:1352)
[error] dotty.tools.dotc.transform.MegaPhase.goDefDef(MegaPhase.scala:1041)
[error] dotty.tools.dotc.transform.MegaPhase.goDefDef(MegaPhase.scala:1042)
[error] dotty.tools.dotc.transform.MegaPhase.goDefDef(MegaPhase.scala:1042)
[error] dotty.tools.dotc.transform.MegaPhase.goDefDef(MegaPhase.scala:1042)
[error] dotty.tools.dotc.transform.MegaPhase.goDefDef(MegaPhase.scala:1042)
[error] dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:268)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:452)
[error] dotty.tools.dotc.transform.MegaPhase.loop$1(MegaPhase.scala:465)
[error] dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:465)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:376)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:454)
[error] dotty.tools.dotc.transform.MegaPhase.transformNamed$1(MegaPhase.scala:272)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:452)
[error] dotty.tools.dotc.transform.MegaPhase.loop$1(MegaPhase.scala:465)
[error] dotty.tools.dotc.transform.MegaPhase.transformStats(MegaPhase.scala:465)
[error] dotty.tools.dotc.transform.MegaPhase.mapPackage$1(MegaPhase.scala:396)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnnamed$1(MegaPhase.scala:399)
[error] dotty.tools.dotc.transform.MegaPhase.transformTree(MegaPhase.scala:454)
[error] dotty.tools.dotc.transform.MegaPhase.transformUnit(MegaPhase.scala:481)
[error] dotty.tools.dotc.transform.MegaPhase.run(MegaPhase.scala:493)
[error] dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:383)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.immutable.List.foreach(List.scala:334)
[error] dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:376)
[error] dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:346)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1324)
[error] dotty.tools.dotc.Run.runPhases$1(Run.scala:339)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$1$$anonfun$2(Run.scala:386)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$1$$anonfun$adapted$1(Run.scala:386)
[error] scala.Function0.apply$mcV$sp(Function0.scala:42)
[error] dotty.tools.dotc.Run.showProgress(Run.scala:448)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:386)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:398)
[error] dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:69)
[error] dotty.tools.dotc.Run.compileUnits(Run.scala:398)
[error] dotty.tools.dotc.Run.compileSources(Run.scala:285)
[error] dotty.tools.dotc.Run.compile(Run.scala:270)
[error] dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
[error] dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:141)
[error] dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
[error] sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:196)
[error] scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
[error] sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:252)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:186)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:166)
[error] sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:241)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:166)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:214)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:542)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:542)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$3(Incremental.scala:178)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$3$adapted(Incremental.scala:176)
[error] sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:454)
[error] sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:117)
[error] sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
[error] sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
[error] sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:265)
[error] sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:409)
[error] sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:496)
[error] sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:396)
[error] sbt.internal.inc.Incremental$.apply(Incremental.scala:204)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:542)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:496)
[error] sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:433)
[error] sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
[error] sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:2419)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$2(Defaults.scala:2369)
[error] sbt.internal.server.BspCompileTask$.$anonfun$compute$1(BspCompileTask.scala:41)
[error] sbt.internal.io.Retry$.apply(Retry.scala:47)
[error] sbt.internal.io.Retry$.apply(Retry.scala:29)
[error] sbt.internal.io.Retry$.apply(Retry.scala:24)
[error] sbt.internal.server.BspCompileTask$.compute(BspCompileTask.scala:41)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:2367)
[error] scala.Function1.$anonfun$compose$1(Function1.scala:49)
[error] sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:63)
[error] sbt.std.Transform$$anon$4.work(Transform.scala:69)
[error] sbt.Execute.$anonfun$submit$2(Execute.scala:283)
[error] sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:24)
[error] sbt.Execute.work(Execute.scala:292)
[error] sbt.Execute.$anonfun$submit$1(Execute.scala:283)
[error] sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:265)
[error] sbt.CompletionService$$anon$2.call(CompletionService.scala:65)
[error] java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error] java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
[error] java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error] java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
[error] java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
[error] java.base/java.lang.Thread.run(Thread.java:834)
[error]
[error] stack trace is suppressed; run 'last Compile / compileIncremental' for the full output
[error] (Compile / compileIncremental) java.lang.AssertionError: assertion failed: TypeAlias(AppliedType(TypeRef(ThisType(TypeRef(NoPrefix,module class scala)),class Tuple2),List(TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),class Int), TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),class Int))))
[error] Total time: 1 s, completed 5. 3. 2025 21:23:36

The text was updated successfully, but these errors were encountered:

OndrejSpanel · 2025-03-05T20:46:30Z

There is no crash when the code is changed from extension (xy: IXY) to extension (xy: (Int, Int)).

soronpo · 2025-03-06T06:07:42Z

Could this be because of SIP62? #22652
cc @KacperFKorban

KacperFKorban · 2025-03-06T08:55:37Z

II tested it and it doesn't seem to be connected to SIP-62, I removed the dropForMap phase and it still crashed. Looks like the bug might be in RefCheck

Gedochao · 2025-03-06T10:43:27Z

Last good nightly: 3.7.0-RC1-bin-20250222-4dc4668-NIGHTLY
First bad nightly: 3.7.0-RC1-bin-20250225-a25fe5e-NIGHTLY

~015f73fe686753e008cbf26a48fce457cd7fbf68 is the first bad commit. ~

cc @hamzaremmal

EDIT: Further investigation indicates that the first bad commit is actually 7d79c56 (#22502)

hamzaremmal · 2025-03-06T10:46:27Z

Last good nightly: 3.7.0-RC1-bin-20250222-4dc4668-NIGHTLY First bad nightly: 3.7.0-RC1-bin-20250225-a25fe5e-NIGHTLY

015f73f is the first bad commit.

cc @hamzaremmal

Euh, I don't see how my commit could have had an impact on this 😅

Gedochao · 2025-03-06T10:57:12Z

It's not impossible that the bisect script crashed on 015f73f for a different reason... #22640 included 3 commits and wasn't squashed.

The fault is most definitely somewhere within the range of 4dc4668..a25fe5e.
So if it's not 015f73f, then it's one of:

Gedochao · 2025-03-06T11:11:25Z

Hmm... Investigating those, I'm getting the exact same crash on 7d79c56
It seems 7d79c56 (#22502) is the actual culprit.
Mental note to improve the bisect script.

cc @hamzaremmal @rochala @julian-a-avar-c @nmcb

hamzaremmal · 2025-03-06T12:49:24Z

Hmm... Investigating those, I'm getting the exact same crash on 7d79c56 It seems 7d79c56 (#22502) is the actual culprit. Mental note to improve the bisect script.

cc @hamzaremmal @rochala @julian-a-avar-c @nmcb

Okay, that has the potential of being faulty.

som-snytt · 2025-03-07T16:15:24Z

I looked at my linked follow-up PR at the duplicate ticket. It fixes the crash.

I added the excellent minimization to the PR.

Fixes scala#22705 Fixes scala#22706 Fixes scala#22727 Follow-up to scala#22502 by inserting a `dealias` when arriving at `target` type. Refactored the body of `hidden` to make it easier to read. Adjusted the doc for the same reason. As a reminder to self, the original reason for special handling of aliases was due to subclassing, but overrides are excluded. (One could restore that warning for edge cases.) The long doc explaining the handling of leading implicits is moved to the end (as an appendix). Despite best efforts, I was unable to make the doc longer than the code. [Cherry-picked d362492]

OndrejSpanel added itype:bug itype:crash stat:needs triage Every issue needs to have an "area" and "itype" label labels Mar 5, 2025

OndrejSpanel mentioned this issue Mar 5, 2025

assertion failed: missing outer accessor #22704

Open

Gedochao removed the stat:needs bisection Need to use nightly builds and git bisect to find out the commit where this issue was introduced label Mar 6, 2025

Gedochao assigned hamzaremmal Mar 6, 2025

mrdziuban mentioned this issue Mar 7, 2025

Compiler crash in 3.7 nightly while compiling http4s-related code, "invalid new prefix" #22737

Closed

som-snytt mentioned this issue Mar 7, 2025

Dealias before checking for member in lint #22708

Merged

som-snytt marked this as a duplicate of #22737 Mar 7, 2025

KacperFKorban closed this as completed in #22708 Mar 10, 2025

KacperFKorban closed this as completed in d362492 Mar 10, 2025

WojciechMazur added this to the 3.7.0 milestone Mar 11, 2025

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3.7 regression: unhandled exception while running MegaPhase - map extension for (Int, Int) #22727

3.7 regression: unhandled exception while running MegaPhase - map extension for (Int, Int) #22727

OndrejSpanel commented Mar 5, 2025 •

edited

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OndrejSpanel commented Mar 5, 2025 •

edited

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soronpo commented Mar 6, 2025

KacperFKorban commented Mar 6, 2025

Gedochao commented Mar 6, 2025 •

edited

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hamzaremmal commented Mar 6, 2025

Gedochao commented Mar 6, 2025

Gedochao commented Mar 6, 2025

hamzaremmal commented Mar 6, 2025

som-snytt commented Mar 7, 2025 •

edited

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3.7 regression: unhandled exception while running MegaPhase - map extension for (Int, Int) #22727

3.7 regression: unhandled exception while running MegaPhase - map extension for (Int, Int) #22727

Comments

OndrejSpanel commented Mar 5, 2025 • edited Loading

Compiler version

Minimized code

Output (click arrow to expand)

OndrejSpanel commented Mar 5, 2025 • edited Loading

soronpo commented Mar 6, 2025

KacperFKorban commented Mar 6, 2025

Gedochao commented Mar 6, 2025 • edited Loading

hamzaremmal commented Mar 6, 2025

Gedochao commented Mar 6, 2025

Gedochao commented Mar 6, 2025

hamzaremmal commented Mar 6, 2025

som-snytt commented Mar 7, 2025 • edited Loading

OndrejSpanel commented Mar 5, 2025 •

edited

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OndrejSpanel commented Mar 5, 2025 •

edited

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Gedochao commented Mar 6, 2025 •

edited

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som-snytt commented Mar 7, 2025 •

edited

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