From 6b1eda35a358f49f2d367177fea6a361acef5ea6 Mon Sep 17 00:00:00 2001
From: odersky <odersky@gmail.com>
Date: Sun, 25 Sep 2022 12:14:02 +0200
Subject: [PATCH 1/3] Test case

---
 tests/neg/i16095.scala | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 tests/neg/i16095.scala

diff --git a/tests/neg/i16095.scala b/tests/neg/i16095.scala
new file mode 100644
index 000000000000..b1547bae6b68
--- /dev/null
+++ b/tests/neg/i16095.scala
@@ -0,0 +1,30 @@
+package x
+
+import scala.annotation.*
+import scala.concurrent.*
+
+@capability
+class CpsTransform[F[_]] {
+     def await[T](ft: F[T]): { this } T = ???
+}
+
+inline def cpsAsync[F[_]] =
+  Test.InfernAsyncArg
+object Test {
+
+  class InfernAsyncArg[F[_]] {
+      def apply[A](expr: CpsTransform[F] ?=> A): F[A] = ???
+  }
+
+  def asyncPlus[F[_]](a:Int, b:F[Int])(using cps: CpsTransform[F]): { cps } Int =
+    a + cps.await(b)
+
+  def testExample1Future(): Unit =
+     val fr = cpsAsync[Future] {
+        val y = asyncPlus(1,Future successful 2)
+        y+1
+     }
+     val r = Await.result(fr)
+     assert(r == Success(3))
+
+}
\ No newline at end of file

From 65544545034d66f88f10464e1de6b8be1deb3f54 Mon Sep 17 00:00:00 2001
From: odersky <odersky@gmail.com>
Date: Sun, 25 Sep 2022 21:32:58 +0200
Subject: [PATCH 2/3] Avoid crash where creator proxies are referenced
 indirectly

Fixes #16095
---
 .../src/dotty/tools/dotc/typer/Typer.scala    |  2 ++
 tests/neg/i16095.scala                        | 24 ++++---------------
 2 files changed, 7 insertions(+), 19 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/typer/Typer.scala b/compiler/src/dotty/tools/dotc/typer/Typer.scala
index 17271618cf09..b8e8bd68c8f8 100644
--- a/compiler/src/dotty/tools/dotc/typer/Typer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Typer.scala
@@ -4013,6 +4013,8 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
           cpy.Select(qual)(pre, name.toTypeName)
         case qual: This if qual.symbol.is(ModuleClass) =>
           cpy.Ident(qual)(qual.symbol.name.sourceModuleName.toTypeName)
+        case _ =>
+          errorTree(tree, em"cannot convert to $tree to an instance creation expression")
       val tycon = tree.tpe.widen.finalResultType.underlyingClassRef(refinementOK = false)
       typed(
         untpd.Select(
diff --git a/tests/neg/i16095.scala b/tests/neg/i16095.scala
index b1547bae6b68..1d8085cec53f 100644
--- a/tests/neg/i16095.scala
+++ b/tests/neg/i16095.scala
@@ -1,30 +1,16 @@
 package x
 
-import scala.annotation.*
 import scala.concurrent.*
 
-@capability
-class CpsTransform[F[_]] {
-     def await[T](ft: F[T]): { this } T = ???
-}
-
-inline def cpsAsync[F[_]] =
+def cpsAsync[F[_]] =
   Test.InfernAsyncArg
-object Test {
 
+object Test {
   class InfernAsyncArg[F[_]] {
-      def apply[A](expr: CpsTransform[F] ?=> A): F[A] = ???
+    def apply[A](): F[A] = ???
   }
-
-  def asyncPlus[F[_]](a:Int, b:F[Int])(using cps: CpsTransform[F]): { cps } Int =
-    a + cps.await(b)
+  object InfernAsyncArg
 
   def testExample1Future(): Unit =
-     val fr = cpsAsync[Future] {
-        val y = asyncPlus(1,Future successful 2)
-        y+1
-     }
-     val r = Await.result(fr)
-     assert(r == Success(3))
-
+    val fr = cpsAsync[Future]() // error
 }
\ No newline at end of file

From 873338e01f101ab599505281e389a671922aeb0e Mon Sep 17 00:00:00 2001
From: odersky <odersky@gmail.com>
Date: Mon, 26 Sep 2022 12:08:28 +0200
Subject: [PATCH 3/3] Update compiler/src/dotty/tools/dotc/typer/Typer.scala

Co-authored-by: Jan Chyb <48855024+jchyb@users.noreply.github.com>
---
 compiler/src/dotty/tools/dotc/typer/Typer.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler/src/dotty/tools/dotc/typer/Typer.scala b/compiler/src/dotty/tools/dotc/typer/Typer.scala
index b8e8bd68c8f8..6a1e6e0b671f 100644
--- a/compiler/src/dotty/tools/dotc/typer/Typer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Typer.scala
@@ -4014,7 +4014,7 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
         case qual: This if qual.symbol.is(ModuleClass) =>
           cpy.Ident(qual)(qual.symbol.name.sourceModuleName.toTypeName)
         case _ =>
-          errorTree(tree, em"cannot convert to $tree to an instance creation expression")
+          errorTree(tree, em"cannot convert from $tree to an instance creation expression")
       val tycon = tree.tpe.widen.finalResultType.underlyingClassRef(refinementOK = false)
       typed(
         untpd.Select(