crash when summon sum mirror of intersection type

[bishabosha]

Compiler version

3.1.2

Minimized code

import scala.deriving.Mirror

trait Mixin

sealed trait Fruit extends Mixin
object Fruit {
  case object Apple extends Fruit
  case object Orange extends Fruit
}

@main def Test = {
  summon[Mirror.SumOf[Fruit & Mixin]]
}

Output (click arrow to expand)

Exception in thread "main" scala.MatchError: AndType(TypeRef(ThisType(TypeRef(NoPrefix,module class <empty>)),trait Fruit),TypeRef(ThisType(TypeRef(NoPrefix,module class <empty>)),trait Mixin)) (of class dotty.tools.dotc.core.Types$CachedAndType) while compiling /Users/jamie/workspace/dotty/local/foo/App.scala
scala.MatchError: AndType(TypeRef(ThisType(TypeRef(NoPrefix,module class <empty>)),trait Fruit),TypeRef(ThisType(TypeRef(NoPrefix,module class <empty>)),trait Mixin)) (of class dotty.tools.dotc.core.Types$CachedAndType)
	at dotty.tools.dotc.transform.TypeUtils$.companionRef(TypeUtils.scala:91)
	at dotty.tools.dotc.typer.Synthesizer.companionPath(Synthesizer.scala:208)
	at dotty.tools.dotc.typer.Synthesizer.sumMirror(Synthesizer.scala:327)
	at dotty.tools.dotc.typer.Synthesizer.$init$$$anonfun$6$$anonfun$1$$anonfun$1$$anonfun$1(Synthesizer.scala:352)
	at dotty.tools.dotc.typer.Synthesizer.makeMirror(Synthesizer.scala:338)
	at dotty.tools.dotc.typer.Synthesizer.$init$$$anonfun$6$$anonfun$1(Synthesizer.scala:352)
	at dotty.tools.dotc.typer.Synthesizer.recur$1(Synthesizer.scala:505)
	at dotty.tools.dotc.typer.Synthesizer.tryAll(Synthesizer.scala:510)
	at dotty.tools.dotc.typer.Implicits.inferImplicitArg(Implicits.scala:863)
	at dotty.tools.dotc.typer.Implicits.inferImplicitArg$(Implicits.scala:791)
	at dotty.tools.dotc.typer.Typer.inferImplicitArg(Typer.scala:119)
	at dotty.tools.dotc.typer.Typer.implicitArgs$1(Typer.scala:3428)
	at dotty.tools.dotc.typer.Typer.addImplicitArgs$1(Typer.scala:3464)
	at dotty.tools.dotc.typer.Typer.adaptNoArgsImplicitMethod$1(Typer.scala:3544)
	at dotty.tools.dotc.typer.Typer.adaptNoArgs$1(Typer.scala:3742)
	at dotty.tools.dotc.typer.Typer.adapt1(Typer.scala:3976)
	at dotty.tools.dotc.typer.Typer.adapt(Typer.scala:3306)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2937)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2941)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3057)
	at dotty.tools.dotc.typer.Typer.typedBlock(Typer.scala:1075)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2817)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2872)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2937)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2941)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3057)
	at dotty.tools.dotc.typer.Namer.typedAheadExpr$$anonfun$1(Namer.scala:1473)
	at dotty.tools.dotc.typer.Namer.typedAhead(Namer.scala:1463)
	at dotty.tools.dotc.typer.Namer.typedAheadExpr(Namer.scala:1473)
	at dotty.tools.dotc.typer.Namer.typedAheadRhs$1$$anonfun$1(Namer.scala:1710)
	at dotty.tools.dotc.typer.PrepareInlineable$.dropInlineIfError(PrepareInlineable.scala:238)
	at dotty.tools.dotc.typer.Namer.typedAheadRhs$1(Namer.scala:1710)
	at dotty.tools.dotc.typer.Namer.rhsType$1(Namer.scala:1718)
	at dotty.tools.dotc.typer.Namer.cookedRhsType$1(Namer.scala:1736)
	at dotty.tools.dotc.typer.Namer.lhsType$1(Namer.scala:1737)
	at dotty.tools.dotc.typer.Namer.inferredResultType(Namer.scala:1748)
	at dotty.tools.dotc.typer.Namer.inferredType$1(Namer.scala:1512)
	at dotty.tools.dotc.typer.Namer.valOrDefDefSig(Namer.scala:1519)
	at dotty.tools.dotc.typer.Namer.defDefSig(Namer.scala:1588)
	at dotty.tools.dotc.typer.Namer$Completer.typeSig(Namer.scala:782)
	at dotty.tools.dotc.typer.Namer$Completer.completeInCreationContext(Namer.scala:914)
	at dotty.tools.dotc.typer.Namer$Completer.complete(Namer.scala:806)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.completeFrom(SymDenotations.scala:168)
	at dotty.tools.dotc.core.Denotations$Denotation.completeInfo$1(Denotations.scala:188)
	at dotty.tools.dotc.core.Denotations$Denotation.info(Denotations.scala:190)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.ensureCompleted(SymDenotations.scala:370)
	at dotty.tools.dotc.typer.Typer.retrieveSym(Typer.scala:2751)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2776)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2871)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2937)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2941)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2963)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3013)
	at dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:2454)
	at dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$1(Typer.scala:2797)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2801)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2871)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2937)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2941)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2963)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3013)
	at dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:2581)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2842)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2872)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2937)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2941)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3057)
	at dotty.tools.dotc.typer.TyperPhase.typeCheck$$anonfun$1(TyperPhase.scala:47)
	at dotty.tools.dotc.core.Phases$Phase.monitor(Phases.scala:411)
	at dotty.tools.dotc.typer.TyperPhase.typeCheck(TyperPhase.scala:54)
	at dotty.tools.dotc.typer.TyperPhase.runOn$$anonfun$3(TyperPhase.scala:88)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:333)
	at dotty.tools.dotc.typer.TyperPhase.runOn(TyperPhase.scala:88)
	at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:259)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1328)
	at dotty.tools.dotc.Run.runPhases$1(Run.scala:270)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:278)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:68)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:287)
	at dotty.tools.dotc.Run.compileSources(Run.scala:220)
	at dotty.tools.dotc.Run.compile(Run.scala:204)
	at dotty.tools.dotc.Driver.doCompile(Driver.scala:39)
	at dotty.tools.dotc.Driver.process(Driver.scala:199)
	at dotty.tools.dotc.Driver.process(Driver.scala:167)
	at dotty.tools.dotc.Driver.process(Driver.scala:179)
	at dotty.tools.dotc.Driver.main(Driver.scala:209)
	at dotty.tools.dotc.Main.main(Main.scala)

[bishabosha]

hard to know what to do in this case, in the case of product types then one part of the intersection is chosen to be the mirror, so there is no intersection in the companion path, but in the case of sum types then one part of the intersection is known to be a subclass of the other, so in mirrorCompanionRef we can take advantage of that.