Merge pull request #5106 from milessabin/topic/hkgadt

SI-9760 Fix for higher-kinded GADT refinement

4 files changed, 101 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Infer.scala b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
index dc91d23011..7112edd75d 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Infer.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
@@ -1257,7 +1257,6 @@ trait Infer extends Checkable {
       def isFreeTypeParamOfTerm(sym: Symbol) = (
         sym.isAbstractType
           && sym.owner.isTerm
-          && !sym.info.bounds.exists(_.typeParams.nonEmpty)
         )
 
       // Intentionally *not* using `Type#typeSymbol` here, which would normalize `tp`
diff --git a/test/files/neg/hkgadt.check b/test/files/neg/hkgadt.check
new file mode 100644
index 0000000000..ef302a9abf
--- /dev/null
+++ b/test/files/neg/hkgadt.check
@@ -0,0 +1,31 @@
+hkgadt.scala:7: error: type mismatch;
+ found   : scala.collection.immutable.Set[Int]
+ required: F[Int]
+      case Bar() => Set(1)
+                       ^
+hkgadt.scala:13: error: type mismatch;
+ found   : Boolean(true)
+ required: A
+    case Bar1() => true
+                   ^
+hkgadt.scala:24: error: type mismatch;
+ found   : scala.collection.immutable.Set[Int]
+ required: F[Int]
+      case Bar() => Set(1)
+                       ^
+hkgadt.scala:25: error: type mismatch;
+ found   : List[Int]
+ required: F[Int]
+      case Baz() => List(1)
+                        ^
+hkgadt.scala:32: error: type mismatch;
+ found   : Boolean(true)
+ required: A
+    case Bar1() => true
+                   ^
+hkgadt.scala:33: error: type mismatch;
+ found   : Int(1)
+ required: A
+    case Baz1() => 1
+                   ^
+6 errors found
diff --git a/test/files/neg/hkgadt.scala b/test/files/neg/hkgadt.scala
new file mode 100644
index 0000000000..0107d2bdde
--- /dev/null
+++ b/test/files/neg/hkgadt.scala
@@ -0,0 +1,35 @@
+object HKGADT {
+  sealed trait Foo[F[_]]
+  final case class Bar() extends Foo[List]
+
+  def frob[F[_]](foo: Foo[F]): F[Int] =
+    foo match {
+      case Bar() => Set(1)
+    }
+
+  sealed trait Foo1[F]
+  final case class Bar1() extends Foo1[Int]
+  def frob1[A](foo: Foo1[A]): A = foo match {
+    case Bar1() => true
+  }
+}
+
+object HKGADT2 {
+  sealed trait Foo[F[_]]
+  final case class Bar() extends Foo[List]
+  final case class Baz() extends Foo[Set]
+
+  def frob[F[_]](foo: Foo[F]): F[Int] =
+    foo match {
+      case Bar() => Set(1)
+      case Baz() => List(1)
+    }
+
+  sealed trait Foo1[F]
+  final case class Bar1() extends Foo1[Int]
+  final case class Baz1() extends Foo1[Boolean]
+  def frob1[A](foo: Foo1[A]): A = foo match {
+    case Bar1() => true
+    case Baz1() => 1
+  }
+}
diff --git a/test/files/pos/hkgadt.scala b/test/files/pos/hkgadt.scala
new file mode 100644
index 0000000000..5719c752cd
--- /dev/null
+++ b/test/files/pos/hkgadt.scala
@@ -0,0 +1,35 @@
+object HKGADT {
+  sealed trait Foo[F[_]]
+  final case class Bar() extends Foo[List]
+
+  def frob[F[_]](foo: Foo[F]): F[Int] =
+    foo match {
+      case Bar() => List(1)
+    }
+
+  sealed trait Foo1[F]
+  final case class Bar1() extends Foo1[Int]
+  def frob1[A](foo: Foo1[A]): A = foo match {
+    case Bar1() => 1
+  }
+}
+
+object HKGADT2 {
+  sealed trait Foo[F[_]]
+  final case class Bar() extends Foo[List]
+  final case class Baz() extends Foo[Set]
+
+  def frob[F[_]](foo: Foo[F]): F[Int] =
+    foo match {
+      case Bar() => List(1)
+      case Baz() => Set(1)
+    }
+
+  sealed trait Foo1[F]
+  final case class Bar1() extends Foo1[Int]
+  final case class Baz1() extends Foo1[Boolean]
+  def frob1[A](foo: Foo1[A]): A = foo match {
+    case Bar1() => 1
+    case Baz1() => true
+  }
+}