Crash involving type bounds in pattern matching

[anatoliykmetyuk]

minimized code

val x = "foo" match
  case _: (a *: (b: Any)) => ???

Stack trace

-- [E040] Syntax Error: ../pg/Macros.scala:31:18 -------------------------------
31 |  case _: (a *: (b: Any)) => ???
   |                  ^
   |                  ')' expected, but ':' found
exception occurred while typechecking ../pg/Macros.scala
exception occurred while compiling ../pg/Macros.scala
scala.MatchError: Parens(Ident(b)) (of class dotty.tools.dotc.ast.untpd$Parens) while compiling ../pg/Macros.scala
Exception in thread "main" scala.MatchError: Parens(Ident(b)) (of class dotty.tools.dotc.ast.untpd$Parens)
	at dotty.tools.dotc.ast.desugar$.patternVar(Desugar.scala:1111)
	at dotty.tools.dotc.typer.Typer.typedArg$1(Typer.scala:1365)
	at dotty.tools.dotc.typer.Typer.$anonfun$23(Typer.scala:1392)
	at dotty.tools.dotc.core.Decorators$ListDecorator$.zipWithConserve$extension(Decorators.scala:110)
	at dotty.tools.dotc.core.Decorators$ListDecorator$.zipWithConserve$extension(Decorators.scala:111)
	at dotty.tools.dotc.typer.Typer.typedAppliedTypeTree(Typer.scala:1392)
	at dotty.tools.dotc.typer.Typer.typedInfixOp(Typer.scala:1956)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2098)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2117)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2104)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2117)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2153)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2165)
	at dotty.tools.dotc.typer.Typer.typedType(Typer.scala:2243)
	at dotty.tools.dotc.typer.Typer.typedTpt$1(Typer.scala:662)
	at dotty.tools.dotc.typer.Typer.handlePattern$1(Typer.scala:664)
	at dotty.tools.dotc.typer.Typer.typedTyped$$anonfun$3(Typer.scala:671)
	at dotty.tools.dotc.typer.Typer.cases$1(Typer.scala:619)
	at dotty.tools.dotc.typer.Typer.typedTyped(Typer.scala:673)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2066)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2117)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2153)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2165)
	at dotty.tools.dotc.typer.Typer.typedPattern(Typer.scala:2245)
	at dotty.tools.dotc.typer.Typer.typedCase(Typer.scala:1169)
	at dotty.tools.dotc.typer.Typer.typedCases$$anonfun$1(Typer.scala:1129)
	at dotty.tools.dotc.core.Decorators$ListDecorator$.loop$1(Decorators.scala:63)
	at dotty.tools.dotc.core.Decorators$ListDecorator$.mapconserve$extension(Decorators.scala:79)
	at dotty.tools.dotc.typer.Typer.typedCases(Typer.scala:1129)
	at dotty.tools.dotc.typer.Typer.$anonfun$17(Typer.scala:1123)
	at dotty.tools.dotc.typer.Applications.harmonic(Applications.scala:1880)
	at dotty.tools.dotc.typer.Typer.harmonic(Typer.scala:83)
	at dotty.tools.dotc.typer.Typer.typedMatchFinish(Typer.scala:1123)
	at dotty.tools.dotc.typer.Typer.typedMatch(Typer.scala:1105)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2074)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2117)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2153)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2165)
	at dotty.tools.dotc.typer.Namer.typedAheadExpr$$anonfun$1(Namer.scala:1211)
	at dotty.tools.dotc.typer.Namer.typedAhead(Namer.scala:1201)
	at dotty.tools.dotc.typer.Namer.typedAheadExpr(Namer.scala:1211)
	at dotty.tools.dotc.typer.Namer.rhsType$2(Namer.scala:1346)
	at dotty.tools.dotc.typer.Namer.cookedRhsType$1(Namer.scala:1357)
	at dotty.tools.dotc.typer.Namer.lhsType$1(Namer.scala:1358)
	at dotty.tools.dotc.typer.Namer.inferredType$1(Namer.scala:1369)
	at dotty.tools.dotc.typer.Namer.valOrDefDefSig(Namer.scala:1377)
	at dotty.tools.dotc.typer.Namer$Completer.typeSig(Namer.scala:765)
	at dotty.tools.dotc.typer.Namer$Completer.completeInCreationContext(Namer.scala:886)
	at dotty.tools.dotc.typer.Namer$Completer.complete(Namer.scala:796)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.completeFrom(SymDenotations.scala:257)
	at dotty.tools.dotc.core.Denotations$Denotation.completeInfo$1(Denotations.scala:182)
	at dotty.tools.dotc.core.Denotations$Denotation.info(Denotations.scala:184)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.ensureCompleted(SymDenotations.scala:397)
	at dotty.tools.dotc.typer.Typer.retrieveSym(Typer.scala:2013)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2038)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2116)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2153)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2165)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2184)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:2228)
	at dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:1727)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2051)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2116)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2153)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2165)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2184)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:2228)
	at dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:1852)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2092)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2117)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2153)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2165)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:2241)
	at dotty.tools.dotc.typer.FrontEnd.typeCheck$$anonfun$1(FrontEnd.scala:75)
	at dotty.runtime.function.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
	at dotty.tools.dotc.typer.FrontEnd.monitor(FrontEnd.scala:41)
	at dotty.tools.dotc.typer.FrontEnd.typeCheck(FrontEnd.scala:79)
	at dotty.tools.dotc.typer.FrontEnd.runOn$$anonfun$3(FrontEnd.scala:109)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:312)
	at dotty.tools.dotc.typer.FrontEnd.runOn(FrontEnd.scala:109)
	at dotty.tools.dotc.Run.runPhases$4$$anonfun$4(Run.scala:159)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1350)
	at dotty.tools.dotc.Run.runPhases$5(Run.scala:169)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:177)
	at dotty.runtime.function.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:67)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:184)
	at dotty.tools.dotc.Run.compileSources(Run.scala:121)
	at dotty.tools.dotc.Run.compile(Run.scala:104)
	at dotty.tools.dotc.Driver.doCompile(Driver.scala:35)
	at dotty.tools.dotc.Driver.process(Driver.scala:178)
	at dotty.tools.dotc.Driver.process(Driver.scala:147)
	at dotty.tools.dotc.Driver.process(Driver.scala:159)
	at dotty.tools.dotc.Driver.main(Driver.scala:186)
	at dotty.tools.dotc.Main.main(Main.scala)
[error] Nonzero exit code returned from runner: 1
[error] (dotty-compiler / Compile / runMain) Nonzero exit code returned from runner: 1
[error] Total time: 8 s, completed Sep 18, 2019 2:40:44 PM