From 47c16fc4bd13c52cebdb3c61597a31bc0df14216 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 8 Sep 2025 08:07:45 +0200
Subject: [PATCH] SourcePath: Implement boost::hash

---
 src/libutil/include/nix/util/source-path.hh | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/libutil/include/nix/util/source-path.hh b/src/libutil/include/nix/util/source-path.hh
index f7cfc8ef7..08f9fe580 100644
--- a/src/libutil/include/nix/util/source-path.hh
+++ b/src/libutil/include/nix/util/source-path.hh
@@ -119,15 +119,23 @@ struct SourcePath
 
 std::ostream & operator<<(std::ostream & str, const SourcePath & path);
 
+inline std::size_t hash_value(const SourcePath & path)
+{
+    std::size_t hash = 0;
+    boost::hash_combine(hash, path.accessor->number);
+    boost::hash_combine(hash, path.path);
+    return hash;
+}
+
 } // namespace nix
 
 template<>
 struct std::hash<nix::SourcePath>
 {
+    using is_avalanching = std::true_type;
+
     std::size_t operator()(const nix::SourcePath & s) const noexcept
     {
-        std::size_t hash = 0;
-        hash_combine(hash, s.accessor->number, s.path);
-        return hash;
+        return nix::hash_value(s);
     }
 };