Don't add ^ to singleton capabilities during Setup

scala · Jun 26, 2024 · ec1e66d · ec1e66d
1 parent 87e34ed
commit ec1e66d
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Showing 2 changed files with 14 additions and 1 deletion.
diff --git a/compiler/src/dotty/tools/dotc/cc/Setup.scala b/compiler/src/dotty/tools/dotc/cc/Setup.scala
@@ -317,7 +317,7 @@ class Setup extends PreRecheck, SymTransformer, SetupAPI:
             this(expandThrowsAlias(res, exc, Nil))
           case t =>
             // Map references to capability classes C to C^
-            if t.derivesFromCapability && t.typeSymbol != defn.Caps_Exists
+            if t.derivesFromCapability && !t.isSingleton && t.typeSymbol != defn.Caps_Exists
             then CapturingType(t, CaptureSet.universal, boxed = false)
             else normalizeCaptures(mapOver(t))
     end toCapturing

diff --git a/tests/pos-custom-args/captures/cap-problem.scala b/tests/pos-custom-args/captures/cap-problem.scala
@@ -0,0 +1,13 @@
+import language.experimental.captureChecking
+
+trait Suspend:
+  type Suspension
+
+  def resume(s: Suspension): Unit
+
+import caps.Capability
+
+trait Async(val support: Suspend) extends Capability
+
+class CancelSuspension(ac: Async, suspension: ac.support.Suspension):
+  ac.support.resume(suspension)