Regression test for #7888

Author: odersky

tests/pos/i7888.scala

@@ -0,0 +1,8 @@
+def usingSeq[B](f: [A] => Seq[A] => B): B = {
+  f(Nil)
+}
+def crash() = {
+  usingSeq { [A] => (a: Seq[A]) =>
+    a
+  }
+}