From 3d9acd2231a4a7560dcd871d1476831b2e6b0531 Mon Sep 17 00:00:00 2001
From: Nadav Ivgi <nadav@shesek.info>
Date: Fri, 11 Oct 2024 02:47:00 +0300
Subject: [PATCH] Document an error case for at_derivation_index()

---
 src/descriptor/key.rs | 1 +
 src/descriptor/mod.rs | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/descriptor/key.rs b/src/descriptor/key.rs
index 7e034ef99..bafe4c2d6 100644
--- a/src/descriptor/key.rs
+++ b/src/descriptor/key.rs
@@ -627,6 +627,7 @@ impl DescriptorPublicKey {
     /// # Errors
     ///
     /// - If `index` is hardened.
+    /// - If the key contains multi-path derivations
     pub fn at_derivation_index(self, index: u32) -> Result<DefiniteDescriptorKey, ConversionError> {
         let definite = match self {
             DescriptorPublicKey::Single(_) => self,
diff --git a/src/descriptor/mod.rs b/src/descriptor/mod.rs
index 487bbcc45..862fc58c6 100644
--- a/src/descriptor/mod.rs
+++ b/src/descriptor/mod.rs
@@ -596,6 +596,7 @@ impl Descriptor<DescriptorPublicKey> {
     ///
     /// # Errors
     /// - If index ≥ 2^31
+    /// - If the descriptor contains multi-path derivations
     pub fn at_derivation_index(
         &self,
         index: u32,
@@ -650,7 +651,8 @@ impl Descriptor<DescriptorPublicKey> {
     ///
     /// # Errors
     ///
-    /// This function will return an error if hardened derivation is attempted.
+    /// This function will return an error for multi-path descriptors
+    /// or if hardened derivation is attempted,
     pub fn derived_descriptor<C: secp256k1::Verification>(
         &self,
         secp: &secp256k1::Secp256k1<C>,