Don't use raw type ASTs in error message

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -4432,7 +4432,7 @@ object Types {
         typr.println(msg)
         val bound = TypeComparer.fullUpperBound(origin)
         if !(atp <:< bound) then
-          throw new TypeError(s"$msg,\nbut the latter type does not conform to the upper bound $bound")
+          throw new TypeError(i"$msg,\nbut the latter type does not conform to the upper bound $bound")
         atp
       // AVOIDANCE TODO: This really works well only if variables are instantiated from below
       // If we hit a problematic symbol while instantiating from above, then avoidance

tests/neg/i12284.check

@@ -0,0 +1,41 @@
+-- Error: tests/neg/i12284.scala:5:36 ----------------------------------------------------------------------------------
+5 |  val xx: Vector[F[_]] = deps.map(i => magic(i)) // error // error // error
+  |                                  ^^^^^^^^^^^^^
+  |                                  return type B of lambda cannot be made hygienic;
+  |                                  it is not a supertype of the hygienic type Any
+-- Error: tests/neg/i12284.scala:5:33 ----------------------------------------------------------------------------------
+5 |  val xx: Vector[F[_]] = deps.map(i => magic(i)) // error // error // error
+  |                                 ^
+  |                                 Inaccessible variables captured in instantation of type variable B.
+  |                                 F[i.A] was fixed to Any,
+  |                                 but the latter type does not conform to the upper bound F[?]
+-- Error: tests/neg/i12284.scala:5:6 -----------------------------------------------------------------------------------
+5 |  val xx: Vector[F[_]] = deps.map(i => magic(i)) // error // error // error
+  |      ^
+  |      Inaccessible variables captured in instantation of type variable B.
+  |      F[i.A] was fixed to Any,
+  |      but the latter type does not conform to the upper bound F[?]
+-- Error: tests/neg/i12284.scala:4:2 -----------------------------------------------------------------------------------
+4 |  val deps: Vector[I[F, _]] = ??? // error
+  |  ^
+  |  Inaccessible variables captured in instantation of type variable B.
+  |  F[i.A] was fixed to Any,
+  |  but the latter type does not conform to the upper bound F[?]
+-- Error: tests/neg/i12284.scala:3:4 -----------------------------------------------------------------------------------
+3 |def magic[F[_], A](in: I[F, A]): F[A] =  // error // error
+  |    ^
+  |    Inaccessible variables captured in instantation of type variable B.
+  |    F[i.A] was fixed to Any,
+  |    but the latter type does not conform to the upper bound F[?]
+-- Error: tests/neg/i12284.scala:3:0 -----------------------------------------------------------------------------------
+3 |def magic[F[_], A](in: I[F, A]): F[A] =  // error // error
+  |^
+  |Inaccessible variables captured in instantation of type variable B.
+  |F[i.A] was fixed to Any,
+  |but the latter type does not conform to the upper bound F[?]
+-- Error: tests/neg/i12284.scala:1:0 -----------------------------------------------------------------------------------
+1 |trait I[F[_], A]  // error
+  |^
+  |Inaccessible variables captured in instantation of type variable B.
+  |F[i.A] was fixed to Any,
+  |but the latter type does not conform to the upper bound F[?]

tests/neg/i12284.scala

@@ -0,0 +1,6 @@
+trait I[F[_], A]  // error
+
+def magic[F[_], A](in: I[F, A]): F[A] =  // error // error
+  val deps: Vector[I[F, _]] = ??? // error
+  val xx: Vector[F[_]] = deps.map(i => magic(i)) // error // error // error
+  ???