From f5ba0e9b25b5cab678c4274bbb4c80a80d244c31 Mon Sep 17 00:00:00 2001
From: odersky <odersky@gmail.com>
Date: Thu, 18 Jan 2024 16:43:42 +0100
Subject: [PATCH] Use inferred type transformer for SeqLiterals

Fixes #19470
---
 compiler/src/dotty/tools/dotc/cc/Setup.scala | 2 +-
 tests/neg/i19470.check                       | 7 +++++++
 tests/neg/i19470.scala                       | 9 +++++++++
 3 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 tests/neg/i19470.check
 create mode 100644 tests/neg/i19470.scala

diff --git a/compiler/src/dotty/tools/dotc/cc/Setup.scala b/compiler/src/dotty/tools/dotc/cc/Setup.scala
index 18781e5ab713..44e832a20d34 100644
--- a/compiler/src/dotty/tools/dotc/cc/Setup.scala
+++ b/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)
diff --git a/tests/neg/i19470.check b/tests/neg/i19470.check
new file mode 100644
index 000000000000..72f811f7ea3b
--- /dev/null
+++ b/tests/neg/i19470.check
@@ -0,0 +1,7 @@
+-- [E007] Type Mismatch Error: tests/neg/i19470.scala:9:12 -------------------------------------------------------------
+9 |    List(foo(f())) // error
+  |         ^^^^^^^^
+  |         Found:    Inv[? >: IO <: box IO^{f}]
+  |         Required: box Inv[box IO^?]^?
+  |
+  | longer explanation available when compiling with `-explain`
diff --git a/tests/neg/i19470.scala b/tests/neg/i19470.scala
new file mode 100644
index 000000000000..9659f4654042
--- /dev/null
+++ b/tests/neg/i19470.scala
@@ -0,0 +1,9 @@
+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())) // error