Merge pull request #3184 from retronym/ticket/2066

SI-2066 Plug a soundness hole higher order type params, overriding

4 files changed, 112 insertions, 0 deletions

diff --git a/test/files/neg/t2066.check b/test/files/neg/t2066.check
new file mode 100644
index 0000000000..efade87e26
--- /dev/null
+++ b/test/files/neg/t2066.check
@@ -0,0 +1,21 @@
+t2066.scala:6: error: overriding method f in trait A1 of type [T[_]]=> Unit;
+ method f has incompatible type
+  override def f[T[+_]] = ()
+               ^
+t2066.scala:10: error: overriding method f in trait A1 of type [T[_]]=> Unit;
+ method f has incompatible type
+  override def f[T[-_]] = ()
+               ^
+t2066.scala:23: error: overriding method f in trait A2 of type [T[+_]]=> Unit;
+ method f has incompatible type
+  override def f[T[-_]] = ()
+               ^
+t2066.scala:45: error: overriding method f in trait A4 of type [T[X[+_]]]=> Unit;
+ method f has incompatible type
+  override def f[T[X[_]]] = ()
+               ^
+t2066.scala:53: error: overriding method f in trait A5 of type [T[X[-_]]]=> Unit;
+ method f has incompatible type
+  override def f[T[X[_]]] = ()
+               ^
+5 errors found
diff --git a/test/files/neg/t2066.scala b/test/files/neg/t2066.scala
new file mode 100644
index 0000000000..7f15d39c67
--- /dev/null
+++ b/test/files/neg/t2066.scala
@@ -0,0 +1,70 @@
+trait A1 {
+  def f[T[_]] = ()
+}
+
+trait B1 extends A1 {
+  override def f[T[+_]] = ()
+}
+
+trait C1 extends A1 {
+  override def f[T[-_]] = ()
+}
+
+
+trait A2 {
+  def f[T[+_]] = ()
+}
+
+trait B2 extends A2 {
+  override def f[T[_]] = () // okay
+}
+
+trait C2 extends A2 {
+  override def f[T[-_]] = ()
+}
+
+
+trait A3 {
+  def f[T[-_]] = ()
+}
+
+trait B3 extends A3 {
+  override def f[T[_]] = () // okay
+}
+
+trait C3 extends A3 {
+  override def f[T[-_]] = ()
+}
+
+
+trait A4 {
+  def f[T[X[+_]]] = ()
+}
+
+trait B4 extends A4 {
+  override def f[T[X[_]]] = ()
+}
+
+trait A5 {
+  def f[T[X[-_]]] = ()
+}
+
+trait B5 extends A5 {
+  override def f[T[X[_]]] = ()
+}
+
+
+
+trait A6 {
+  def f[T[X[_]]] = ()
+}
+
+trait B6 extends A6 {
+  override def f[T[X[+_]]] = () // okay
+}
+trait C6 extends A6 {
+  override def f[T[X[_]]] = () // okay
+}
+trait D6 extends A6 {
+  override def f[T[X[-_]]] = ()
+}
diff --git a/test/files/neg/t2066b.check b/test/files/neg/t2066b.check
new file mode 100644
index 0000000000..097c44fef3
--- /dev/null
+++ b/test/files/neg/t2066b.check
@@ -0,0 +1,5 @@
+t2066b.scala:7: error: overriding method f in trait A of type [T[_]](x: T[Int])T[Any];
+ method f has incompatible type
+	 def f[T[+_]](x : T[Int]) : T[Any] = x
+             ^
+one error found
diff --git a/test/files/neg/t2066b.scala b/test/files/neg/t2066b.scala
new file mode 100644
index 0000000000..46177b19f7
--- /dev/null
+++ b/test/files/neg/t2066b.scala
@@ -0,0 +1,16 @@
+object Test extends App {
+	trait A {
+	 def f[T[_]](x : T[Int]) : T[Any]
+	}
+
+	class B extends A {
+	 def f[T[+_]](x : T[Int]) : T[Any] = x
+	}
+
+	class P[Y](var y : Y)
+
+	val p = new P(1)
+	val palias = (new B():A).f[P](p)
+	palias.y = "hello"	
+	val z: Int = p.y
+}
\ No newline at end of file