From 1fbc609815783d2a7af9a4800d7ce51b8d822a4f Mon Sep 17 00:00:00 2001
From: Katharine Hyatt <kshyatt@users.noreply.github.com>
Date: Wed, 16 Sep 2026 09:54:36 +0200
Subject: [PATCH] Make ChainRules ext consistent with Mooncake and Enzyme

`degeneracystructure` is marked the equivalent of non-diffable in those extensions
---
 ext/TensorKitChainRulesCoreExt/utility.jl | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/ext/TensorKitChainRulesCoreExt/utility.jl b/ext/TensorKitChainRulesCoreExt/utility.jl
index 6896ff894..ef4afc3f8 100644
--- a/ext/TensorKitChainRulesCoreExt/utility.jl
+++ b/ext/TensorKitChainRulesCoreExt/utility.jl
@@ -24,3 +24,5 @@ function (::ProjectTo{DiagonalTensorMap{T, S, A}})(x::AbstractTensorMap) where {
     end
     return y
 end
+
+@non_differentiable TensorKit.degeneracystructure(::Any)