Use inferred type transformer for SeqLiterals

Fixes #19470

Author: odersky

compiler/src/dotty/tools/dotc/cc/Setup.scala

@@ -416,7 +416,7 @@ class Setup extends PreRecheck, SymTransformer, SetupAPI:
 
         case tree @ SeqLiteral(elems, tpt: TypeTree) =>
           traverse(elems)
-          transformTT(tpt, boxed = true, exact = false)
+          tpt.rememberType(box(transformInferredType(tpt.tpe)))
 
         case _ =>
           traverseChildren(tree)

tests/pos/i19470.scala

@@ -0,0 +1,10 @@
+import language.experimental.captureChecking
+trait IO
+case class Inv[X](x: X)
+
+def foo(x: IO^): Inv[IO^{x}] = Inv(x)
+
+def main(io: IO^): Unit =
+  def test(f: () => IO^) =
+    List(foo(f()))
+