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Fix #5044: guard against forward references in the TypeTree of New trees #5178

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Merged
merged 2 commits into from
Oct 2, 2018
Merged

Fix #5044: guard against forward references in the TypeTree of New trees #5178

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e7c9fce
Fix #5044: guard against forward references in the TypeTree of New trees
Jasper-M Sep 28, 2018
91eaf20
address review
Jasper-M Sep 28, 2018
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8 changes: 6 additions & 2 deletions compiler/src/dotty/tools/dotc/typer/RefChecks.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -1010,9 +1010,14 @@ class RefChecks extends MiniPhase { thisPhase =>
}

override def transformNew(tree: New)(implicit ctx: Context) = {
val sym = tree.tpe.typeSymbol
val tpe = tree.tpe
val sym = tpe.typeSymbol
checkUndesiredProperties(sym, tree.pos)
currentLevel.enterReference(sym, tree.pos)
tpe.dealias.foreachPart {
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Is dealias required?

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@Jasper-M Jasper-M Sep 28, 2018 •
edited
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Without it the second test still fails (crashes). If you would dealias a bit sooner I think def foo = { type T = Foo; val a = new T; class Foo } would also emit an error, like in scalac.

case TermRef(_, s: Symbol) => currentLevel.enterReference(s, tree.pos)
case _ =>
}
tree
}
}
Expand Down Expand Up @@ -1643,4 +1648,3 @@ class RefChecks extends MiniPhase { thisPhase =>
}
}
*/

7 changes: 7 additions & 0 deletions tests/neg/i5044a.scala
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@@ -0,0 +1,7 @@
class I0 {
class I1
def i3 = {
val i4 = new i5.I1 // error: `i5` is a forward reference extending over the definition of `i4`
val i5 = new I0
}
}
8 changes: 8 additions & 0 deletions tests/neg/i5044b.scala
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@@ -0,0 +1,8 @@
class I0 {
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I would merge the two tests together:

class I0 {
  class I1
  def test0 = {
    val x = new y.I1 // error: `y` is a forward reference extending over the definition of `x`
    val y = new I0
  }

  def test1 = {
    type T = y.I1
    val x = new T // error: `y` is a forward reference extending over the definition of `x`
    val y = new I0
  }
}

class I1
def i3 = {
type T = i5.I1
val i4 = new T // error: `i5` is a forward reference extending over the definition of `i4`
val i5 = new I0
}
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Here is another test with a type lambda

class I0 {
  class I2[T1, T2]
  def test2 = {
    type A[T] = i5.I2[T, String]
    val i4 = new A[Int]
    val i5 = new I0
  }
}

This one currently crashes with Scala 2.12.6 😄

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I would also add:

  def test3 = {
    val x = new T // error: `T` is a forward reference extending over the definition of `x`
    val y = new I0
    type T = y.I1
  }

}