From 5d73743971932399a9a0e1cb65688ff3c0dc8f5d Mon Sep 17 00:00:00 2001 From: josh11b <15258583+josh11b@users.noreply.github.com> Date: Sat, 24 Aug 2024 12:44:07 -0700 Subject: [PATCH] Add link for coherence appendix to Swift forums (#4241) Co-authored-by: Josh L Co-authored-by: Chandler Carruth --- docs/design/generics/appendix-coherence.md | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/docs/design/generics/appendix-coherence.md b/docs/design/generics/appendix-coherence.md index dc4ad1a62bd03..68e6d080b8925 100644 --- a/docs/design/generics/appendix-coherence.md +++ b/docs/design/generics/appendix-coherence.md @@ -235,3 +235,9 @@ either: like [dynamic implementation binding](#rejected-variation-dynamic-implementation-binding) (though perhaps with a monomorphization cost instead of a runtime cost). + +In addition, this can create unsoundness when combined with dynamic downcasts +and a more complex, less predictable implementation model as +[discussed in Swift](https://forums.swift.org/t/retroactive-conformances-dynamic-downcast-type-unsoundness/73890). +This approach would be particularly complex in Carbon due to supporting +[impl specialization](terminology.md#specialization).