Merge pull request #14361 from dwijnand/fix-approximating-RefinedTypes

Fix approximating RefinedTypes (n>1)

Author: smarter

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -5802,7 +5802,7 @@ object Types {
             case Range(infoLo: TypeBounds, infoHi: TypeBounds) =>
               assert(variance == 0)
               if (!infoLo.isTypeAlias && !infoHi.isTypeAlias) propagate(infoLo, infoHi)
-              else range(defn.NothingType, tp.parent)
+              else range(defn.NothingType, parent)
             case Range(infoLo, infoHi) =>
               propagate(infoLo, infoHi)
             case _ =>

tests/pos/i14349.min.scala

@@ -0,0 +1,13 @@
+class Inv[M]
+
+class Module:
+  type X
+  type Y
+  type M = Module {
+    type X = Module.this.X
+    type Y = Module.this.Y
+  }
+  def expose = new Inv[M]
+  def test                  = this match { case m => m.expose }
+  // was: leak: `(m : Module)` in `m.expose: Inv[? <: Module { X = m.X }]`
+  def res: Inv[_ <: Module] = this match { case m => m.expose }

tests/pos/i14349.scala

@@ -0,0 +1,19 @@
+trait Module:
+  self =>
+  type M <: Module {
+    type X = self.X
+    type Y = self.Y
+  }
+  type X
+  type Y
+
+  def expose: Expose[X, Y, M]
+
+trait Expose[
+    X0,
+    Y0,
+    M <: Module { type X = X0; type Y = Y0 }
+]
+
+def test(ms: Seq[Option[Module]]): Seq[Expose[_, _, _]] =
+  ms.collect { case Some(module) => module.expose }