Merge pull request #3505 from dotty-staging/3452-test-cases

Add test cases from #3452

Author: allanrenucci

tests/neg/i3542.scala

@@ -0,0 +1,8 @@
+object Test {
+  trait TC[A]
+
+  implicit def case1[F[_]](implicit t: => TC[F[Any]]): TC[String] = ???
+  implicit def case2[G[_]](implicit r: TC[G[Any]]): TC[Int] = ???
+
+  implicitly[TC[Int]] // error: no implicit argument of type TC[Int] found
+}

tests/pos/i3542-1.scala

@@ -0,0 +1,7 @@
+class Foo[T]
+
+object Test {
+  implicit def foo[T](implicit rec: => Foo[T]): Foo[T] = ???
+
+  val bla: Foo[Int] = implicitly[Foo[Int]]
+}

tests/pos/i3542-2.scala

@@ -0,0 +1,20 @@
+trait ::[H, T]
+
+trait Foo[A, R]
+
+trait FooLowPrio {
+  implicit def caseOther[A]: Foo[A, A :: Any] = null
+}
+object Foo extends FooLowPrio {
+  implicit def caseCons[H, HR, T, TR]
+    (implicit // It's a bit artificial: the by name is not required in this example...
+      t: => Foo[T, TR],
+      h: => Foo[H, HR]
+    ): Foo[H :: T, TR] = null
+
+  implicit def caseAny: Foo[Any, Any] = null
+}
+
+object Test {
+  val implicitFoo = implicitly[Foo[Long :: Any, Any]]
+}