Missing desugaring case for extension methods.

[nicolasstucki]

Minimized code

given AnyRef = { // should have been `given AnyRef {`
  extension (n: Int)
    def plus(m: Int): Int = n + m
}

Output (click arrow to expand)

scala.MatchError: ExtMethods(List(),List(List(ValDef(n,Ident(Int),EmptyTree))),List(DefDef(plus,List(),List(List(ValDef(m,Ident(Int),EmptyTree))),Ident(Int),InfixOp(Ident(n),Ident(+),Ident(m))))) (of class dotty.tools.dotc.ast.untpd$ExtMethods) while compiling Foo.scala
Exception in thread "main" scala.MatchError: ExtMethods(List(),List(List(ValDef(n,Ident(Int),EmptyTree))),List(DefDef(plus,List(),List(List(ValDef(m,Ident(Int),EmptyTree))),Ident(Int),InfixOp(Ident(n),Ident(+),Ident(m))))) (of class dotty.tools.dotc.ast.untpd$ExtMethods)
        at dotty.tools.dotc.ast.desugar$.apply(Desugar.scala:1717)
        at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2468)
        at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2484)
        at dotty.tools.dotc.typer.Typer.op$1(Typer.scala:2553)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2554)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2557)
        at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:2671)
        at dotty.tools.dotc.typer.Typer.typedBlock(Typer.scala:871)
        at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2431)
        at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2484)
        at dotty.tools.dotc.typer.Typer.op$1(Typer.scala:2553)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2554)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2557)
        at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:2671)
        at dotty.tools.dotc.typer.Typer.$anonfun$32(Typer.scala:1946)
        at dotty.tools.dotc.typer.PrepareInlineable$.dropInlineIfError(PrepareInlineable.scala:217)
        at dotty.tools.dotc.typer.Typer.typedDefDef(Typer.scala:1946)
        at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2400)
        at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2483)
        at dotty.tools.dotc.typer.Typer.op$1(Typer.scala:2553)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2554)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2557)
        at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2579)
        at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:2627)
        at dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:2081)
        at dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$2(Typer.scala:2411)
        at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2415)
        at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2483)
        at dotty.tools.dotc.typer.Typer.op$1(Typer.scala:2553)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2554)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2557)
        at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2579)
        at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:2627)
        at dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:2207)
        at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2455)
        at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2484)
        at dotty.tools.dotc.typer.Typer.op$1(Typer.scala:2553)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2554)
        at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2557)
        at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:2671)
        at dotty.tools.dotc.typer.FrontEnd.liftedTree1$1(FrontEnd.scala:79)
        at dotty.tools.dotc.typer.FrontEnd.typeCheck$$anonfun$1(FrontEnd.scala:84)
        at dotty.runtime.function.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
        at dotty.tools.dotc.typer.FrontEnd.monitor(FrontEnd.scala:43)
        at dotty.tools.dotc.typer.FrontEnd.typeCheck(FrontEnd.scala:85)
        at dotty.tools.dotc.typer.FrontEnd.runOn$$anonfun$3(FrontEnd.scala:120)
        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:333)
        at dotty.tools.dotc.typer.FrontEnd.runOn(FrontEnd.scala:120)
        at dotty.tools.dotc.Run.runPhases$4$$anonfun$4(Run.scala:180)
        at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:15)
        at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:10)
        at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323)
        at dotty.tools.dotc.Run.runPhases$5(Run.scala:190)
        at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:198)
        at dotty.runtime.function.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
        at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:64)
        at dotty.tools.dotc.Run.compileUnits(Run.scala:205)
        at dotty.tools.dotc.Run.compileSources(Run.scala:142)
        at dotty.tools.dotc.Run.compile(Run.scala:124)
        at dotty.tools.dotc.Driver.doCompile(Driver.scala:38)
        at dotty.tools.dotc.Driver.process(Driver.scala:195)
        at dotty.tools.dotc.Driver.process(Driver.scala:164)
        at dotty.tools.dotc.Driver.process(Driver.scala:176)
        at dotty.tools.dotc.Driver.main(Driver.scala:203)
        at dotty.tools.dotc.Main.main(Main.scala)