Extend test

Author: odersky

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

@@ -376,12 +376,13 @@ class Setup extends PreRecheck, SymTransformer, SetupAPI:
 
       /** 1. Check that parents of capturing types are not pure.
        *  2. Check that types extending caps.Sharable don't have a `cap` in their capture set.
-       *     TODO This is not enough.
+       *     TODO: Is this enough?
        *     We need to also track that we cannot get exclusive capabilities in paths
        *     where some prefix derives from Sharable. Also, can we just
        *     exclude `cap`, or do we have to extend this to all exclusive capabilties?
        *     The problem is that we know what is exclusive in general only after capture
        *     checking, not before.
+       *     But maybe the rules for classification already cover these cases.
        */
       def checkRetainsOK(tp: Type): tp.type =
         tp match

tests/pos-custom-args/captures/restrict-try.scala

@@ -1,10 +1,29 @@
-import caps.{Capability, Control}
+import caps.{Capability, Control, Mutable}
 
 class Try[+T]
 case class Ok[T](x: T) extends Try[T]
 case class Fail(ex: Exception) extends Try[Nothing]
 
+trait Matrix extends Mutable:
+  update def update(): Unit
+
+trait Label extends Control:
+  def break(): Unit
+
 object Try:
-  def apply[T](body: => T): Try[T]^{body.only[Control]} =
-    try Ok(body)
+  def apply[T](body: () => T): Try[T]^{body.only[Control]} =
+    try Ok(body())
     catch case ex: Exception => Fail(ex)
+
+def Test(m: Matrix^, l: Label) =
+  val x =
+    Try:
+      val b = () =>
+        m.update()
+        l.break()
+      val _: () ->{m, l} Unit = b
+      b
+  val y: Try[Unit]^{l} = x
+
+
+