Add neg GADT test

compiler/test/dotty/tools/dotc/GadtTests.scala

@@ -24,6 +24,11 @@ class GadtTests extends ParallelTesting {
  implicit val testGroup: TestGroup = TestGroup("compileGadtTests")
  compileFilesInDir("tests/gadt", defaultOptions).checkCompile()
  }
+
+ @Test def compileGadtNeg: Unit = {
+ implicit val testGroup: TestGroup = TestGroup("compileGadtNeg")
+ compileFilesInDir("tests/gadt-neg", defaultOptions).checkExpectedErrors()
+ }
 }
 
 object GadtTests {

tests/gadt-neg/banal-nested.scala

@@ -0,0 +1,12 @@
+object banal {
+ sealed trait T[A]
+ final case class StrLit(v: String) extends T[String]
+ final case class IntLit(v: Int) extends T[Int]
+
+ def eval[A](t: T[A]): A = t match {
+ case _: T[a] => t match {
+ case StrLit(v) => v
+ case IntLit(_) => "" // error
+ }
+ }
+}

tests/gadt-neg/banal.scala

@@ -0,0 +1,17 @@
+object banal {
+ final case class Box[A](a: A)
+
+ sealed trait T[A]
+ final case class StrLit(v: String) extends T[String]
+ final case class IntLit(v: Int) extends T[Int]
+
+ def evul[A](t: T[A]): A = t match {
+ case StrLit(v) => (v: Any) // error
+ case IntLit(v) => (??? : Nothing)
+ }
+
+ def noeval[A](t: T[A]): Box[A] = t match {
+ case StrLit(v) => Box[Any](v) // error
+ case IntLit(v) => Box[Nothing](???) // error
+ }
+}

tests/gadt-neg/i4075.scala

@@ -0,0 +1,8 @@
+object i4075 {
+ case class One[T](fst: T)
+ def bad[T](e: One[T]) = e match {
+ case foo: One[a] =>
+ val nok: Nothing = foo.fst // error
+ ???
+ }
+}