Bug with inner classe inheritance.

[nicolasstucki]

The following code

trait A {
  class Inner
 }  
trait B extends A {
  class Inner extends super.Inner
}

fails to compile with this error:

6 |               class Inner extends super.Inner
  |                                   ^^^^^^^^^^^
  |                            cyclic inheritance: class Inner extends itself

This pattern can be found in scala-scala/src/library/scala/collection/parallel/ParSeqLike.scala with protected trait Accessor[R, Tp] extends super.Accessor[R, Tp].

Even worse, the compiler crashes when compiling

trait A {
  class Inner
 }  
trait B extends A {
  class Inner extends super.Inner
}

[odersky]

That's no longer allowed. You have to rewrite the inner classes to have different names. Look at the inner Ops classes in subclasses of type scala.math.Numeric to see what needs to be done.

[odersky]

I could not reproduce the crash. Did you paste the wrong test? (it's the same as the one before).

[nicolasstucki]

Oh yes, the correct tests is

trait A {
  class Inner
}  
trait B extends A {
  class Inner2 extends super.Inner
}

[odersky]

That one also works fine for me (?)

[nicolasstucki]

Im getting this in the repl:

scala> trait A {
           class Inner
         }   
defined trait A
scala> trait B extends A {
           class Inner2 extends super.Inner
         }exception while typing [cannot display due to dotty.tools.dotc.core.Denotations$StaleSymbol: stale symbol; method line1$object$$iw$$iw$A$Inner$$$outer#32842 in class Inner, defined in Period(19..32, run = 4), is referred to in run Period(32..32, run = 6), raw string = dotty.tools.dotc.printing.Formatting$StringFormatter@18bf3d14] of class class dotty.tools.dotc.ast.Trees$Apply # 2297
exception while typing [cannot display due to dotty.tools.dotc.core.Denotations$StaleSymbol: stale symbol; method line1$object$$iw$$iw$A$Inner$$$outer#32842 in class Inner, defined in Period(19..32, run = 4), is referred to in run Period(32..32, run = 6), raw string = dotty.tools.dotc.printing.Formatting$StringFormatter@4fb64261] of class class dotty.tools.dotc.ast.Trees$TypeDef # 2318
exception while typing [cannot display due to dotty.tools.dotc.core.Denotations$StaleSymbol: stale symbol; method line1$object$$iw$$iw$A$Inner$$$outer#32842 in class Inner, defined in Period(19..32, run = 4), is referred to in run Period(32..32, run = 6), raw string = dotty.tools.dotc.printing.Formatting$StringFormatter@42607a4f] of class class dotty.tools.dotc.ast.Trees$TypeDef # 2320
exception while typing [cannot display due to dotty.tools.dotc.core.Denotations$StaleSymbol: stale symbol; method line1$object$$iw$$iw$A$Inner$$$outer#32842 in class Inner, defined in Period(19..32, run = 4), is referred to in run Period(32..32, run = 6), raw string = dotty.tools.dotc.printing.Formatting$StringFormatter@782663d3] of class class dotty.tools.dotc.ast.Trees$TypeDef # 2322
exception while typing [cannot display due to dotty.tools.dotc.core.Denotations$StaleSymbol: stale symbol; method line1$object$$iw$$iw$A$Inner$$$outer#32842 in class Inner, defined in Period(19..32, run = 4), is referred to in run Period(32..32, run = 6), raw string = dotty.tools.dotc.printing.Formatting$StringFormatter@1990a65e] of class class dotty.tools.dotc.ast.Trees$TypeDef # 2324
exception while typing [cannot display due to dotty.tools.dotc.core.Denotations$StaleSymbol: stale symbol; method line1$object$$iw$$iw$A$Inner$$$outer#32842 in class Inner, defined in Period(19..32, run = 4), is referred to in run Period(32..32, run = 6), raw string = dotty.tools.dotc.printing.Formatting$StringFormatter@64485a47] of class class dotty.tools.dotc.ast.Trees$TypeDef # 2326
exception while typing [cannot display due to dotty.tools.dotc.core.Denotations$StaleSymbol: stale symbol; method line1$object$$iw$$iw$A$Inner$$$outer#32842 in class Inner, defined in Period(19..32, run = 4), is referred to in run Period(32..32, run = 6), raw string = dotty.tools.dotc.printing.Formatting$StringFormatter@25bbf683] of class class dotty.tools.dotc.ast.Trees$PackageDef # 2327
Exception in thread "main" dotty.tools.dotc.core.Denotations$StaleSymbol: stale symbol; method line1$object$$iw$$iw$A$Inner$$$outer#32842 in class Inner, defined in Period(19..32, run = 4), is referred to in run Period(32..32, run = 6)
	at dotty.tools.dotc.core.Denotations$SingleDenotation.staleSymbolError(Denotations.scala:932)
	at dotty.tools.dotc.core.Denotations$SingleDenotation.bringForward(Denotations.scala:742)
	at dotty.tools.dotc.core.Denotations$SingleDenotation.current(Denotations.scala:786)
	at dotty.tools.dotc.core.Symbols$Symbol.denot(Symbols.scala:387)
	at dotty.tools.dotc.core.Scopes$Scope.denotsNamed(Scopes.scala:119)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.membersNamed(SymDenotations.scala:1592)
	at dotty.tools.dotc.core.SymDenotations$ClassDenotation.findMember(SymDenotations.scala:1645)
	at dotty.tools.dotc.core.Types$Type.go$1(Types.scala:445)
	at dotty.tools.dotc.core.Types$Type.findMember(Types.scala:580)
	at dotty.tools.dotc.core.Types$Type.memberExcluding(Types.scala:414)
	at dotty.tools.dotc.core.Types$Type$$anonfun$member$1.apply(Types.scala:398)
	at dotty.tools.dotc.core.Types$Type$$anonfun$member$1.apply(Types.scala:398)
	at dotty.tools.dotc.util.Stats$.track(Stats.scala:35)

[nicolasstucki]

It looks like the issue is only in the repl