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Fix #7965: Deal with AndTypes in joins #7992

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Merged
merged 4 commits into from
Jan 15, 2020
Merged

Fix #7965: Deal with AndTypes in joins #7992

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6c0b801
Fix #7965: Deal with AndTypes in joins
odersky Jan 15, 2020
744b5b0
Avoid -Ycheck error by refining <:< testing
odersky Jan 15, 2020
9878eb1
Also handle refinements in joins with AndTypes
odersky Jan 15, 2020
91cf80d
Address review comments
odersky Jan 15, 2020
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4 changes: 4 additions & 0 deletions compiler/src/dotty/tools/dotc/core/TypeOps.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -212,6 +212,8 @@ trait TypeOps { this: Context => // TODO: Make standalone object.
tp1.derivedAppliedType(
mergeRefinedOrApplied(tycon1, tycon2),
ctx.typeComparer.lubArgs(args1, args2, tycon1.typeParams))
case AndType(tp21, tp22) =>
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This handles having tp1 be an AppliedType and tp2 be an AndType, but it seems that we'd need similar special cases when tp1 is a RefinedType and tp2 is an AndType, etc. Instead maybe all calls to fail in this method could be replaced by a fallback that handles the recursion when tp2 is an AndType.

mergeRefinedOrApplied(tp1, tp21) & mergeRefinedOrApplied(tp1, tp22)
case _ => fail
}
case tp1 @ TypeRef(pre1, _) =>
Expand All @@ -220,6 +222,8 @@ trait TypeOps { this: Context => // TODO: Make standalone object.
tp1.derivedSelect(pre1 | pre2)
case _ => fail
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@smarter smarter Jan 15, 2020 •
edited
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The fallback is also necessary here, otherwise the following would crash:

class Outer {
  class Elem
}

class Test {
  val o1: Outer = ???
  val o2: Outer = ???
  val o3: Outer = ???

  val x: o1.Elem | (o2.Elem & o3.Elem)
  def foo[T <: Outer#Elem](has: T): T = ???
  foo(x)
}

}
case AndType(tp11, tp12) =>
mergeRefinedOrApplied(tp11, tp2) & mergeRefinedOrApplied(tp12, tp2)
case _ => fail
}
}
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46 changes: 46 additions & 0 deletions tests/pos/i7965.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,46 @@
class Has[A]
trait X
trait Y
trait Z

abstract class Test {
val x: Has[X] | (Has[Y] & Has[Z])
def foo[T <: Has[_]](has: T): T = has
foo(x)
}

trait ZLayer[-RIn, +E, +ROut <: Has[_]] {
def >>>[E1 >: E, ROut2 <: Has[_]](that: ZLayer[ROut, E1, ROut2]): ZLayer[RIn, E1, ROut2]
def ++[E1 >: E, RIn2, ROut1 >: ROut <: Has[_], ROut2 <: Has[_]](that: ZLayer[RIn2, E1, ROut2]): ZLayer[RIn with RIn2, E1, ROut1 with ROut2]
}
object ZLayer {
type NoDeps[+E, +B <: Has[_]] = ZLayer[Any, E, B]
}

type ServiceA = Has[ServiceA.Service]
object ServiceA {
trait Service
val live: ZLayer.NoDeps[Nothing, ServiceA] = ???
}

type ServiceB = Has[ServiceB.Service]
object ServiceB {
trait Service
val live: ZLayer.NoDeps[Nothing, ServiceB] = ???
}

type ServiceC = Has[ServiceC.Service]
object ServiceC {
trait Service
val live: ZLayer.NoDeps[Nothing, ServiceC] = ???
}

type ServiceD = Has[ServiceD.Service]
object ServiceD {
trait Service
val live: ZLayer.NoDeps[ServiceC, ServiceD with ServiceC] = ???
}

val combined =
ServiceA.live >>>
(ServiceB.live ++ (ServiceC.live >>> ServiceD.live))