refactor(3p/nix): Apply clang-tidy's performance-* fixes r/789

This applies the performance fixes listed here:

https://clang.llvm.org/extra/clang-tidy/checks/list.html

1 files changed, 1 insertions, 1 deletions

diff --git a/third_party/nix/src/libstore/binary-cache-store.cc b/third_party/nix/src/libstore/binary-cache-store.cc
index b0d8c81d80..487c12b531 100644
--- a/third_party/nix/src/libstore/binary-cache-store.cc
+++ b/third_party/nix/src/libstore/binary-cache-store.cc
@@ -98,7 +98,7 @@ Path BinaryCacheStore::narInfoFileFor(const Path& storePath) {
   return storePathToHash(storePath) + ".narinfo";
 }
 
-void BinaryCacheStore::writeNarInfo(ref<NarInfo> narInfo) {
+void BinaryCacheStore::writeNarInfo(const ref<NarInfo>& narInfo) {
   auto narInfoFile = narInfoFileFor(narInfo->path);
 
   upsertFile(narInfoFile, narInfo->to_string(), "text/x-nix-narinfo");