Fix #2887: Add regression test

tests/neg/i2887a.scala

@@ -0,0 +1,13 @@
+trait A { type L[G[F[_],_],H[F[_],_]] }
+trait B { type L[F[_],_] }
+trait C { type M <: A }
+trait D { type M >: B }
+
+object Test {
+  def test(x: C with D): Unit = {
+    def foo(a: A, b: B)(z: a.L[b.L,b.L]) = z
+    def bar(y: x.M, b: B) = foo(y, b)
+    def baz(b: B) = bar(b, b)
+    baz(new B { type L[F[_],X] = F[X] })(1) // error
+  }
+}

tests/neg/i2887b.scala

@@ -0,0 +1,13 @@
+trait A { type S[X[_] <: [_] => Any, Y[_]] <: [_] => Any; type I[_] } // error // error
+trait B { type S[X[_],Y[_]]; type I[_] <: [_] => Any } // error
+trait C { type M <: B }
+trait D { type M >: A }
+
+object Test {
+  def test(x: C with D): Unit = {
+    def foo(a: A, b: B)(z: a.S[b.I,a.I][b.S[a.I,a.I]]) = z // error
+    def bar(a: A, y: x.M) = foo(a,y)
+    def baz(a: A) = bar(a, a)
+    baz(new A { type S[X[_] <: [_] => Any, Y[_]] = [Z] => X[Z][Y[Z]]; type I[X] = X })(1) // error // error
+  }
+}

tests/neg/i2887c.scala

@@ -0,0 +1,13 @@
+trait A { type S[X[_,_], Y[_],_]; type I[_] }
+trait B { type S[X[_],Y[_]]; type I[_,_] }
+trait C { type M <: B }
+trait D { type M >: A }
+
+object Test {
+  def test(x: C with D): Unit = {
+    def foo(a: A, b: B)(z: a.S[b.I,a.I,b.S[a.I,a.I]]) = z
+    def bar(a: A, y: x.M) = foo(a,y)
+    def baz(a: A) = bar(a, a)
+    baz(new A { type S[X[_,_], Y[_], Z] = X[Z,Y[Z]]; type I[X] = X })(1) // error
+  }
+}