From e41c1e27f3f43c4d227cc323bbc30d14aacab408 Mon Sep 17 00:00:00 2001
From: Paul Brauner <paul.brauner@digitalasset.com>
Date: Thu, 14 Nov 2024 18:27:55 +0100
Subject: [PATCH] allow losing observers that are also signatories

---
 .../main/scala/com/digitalasset/daml/lf/speedy/SBuiltin.scala  | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sdk/daml-lf/interpreter/src/main/scala/com/digitalasset/daml/lf/speedy/SBuiltin.scala b/sdk/daml-lf/interpreter/src/main/scala/com/digitalasset/daml/lf/speedy/SBuiltin.scala
index 3782ef76d056..618f8b11eb80 100644
--- a/sdk/daml-lf/interpreter/src/main/scala/com/digitalasset/daml/lf/speedy/SBuiltin.scala
+++ b/sdk/daml-lf/interpreter/src/main/scala/com/digitalasset/daml/lf/speedy/SBuiltin.scala
@@ -2402,7 +2402,8 @@ private[lf] object SBuiltin {
 
     List(
       check(_.signatories, "signatories"),
-      check(_.observers, "observers"),
+      // This definition of observers allows observers to lose parties that are signatories
+      check(c => c.stakeholders -- c.signatories, "observers"),
       check(_.keyOpt.map(_.maintainers), "key maintainers"),
       check(_.keyOpt.map(_.globalKey.key), "key value"),
     ).flatten match {