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, 2 insertions, 2 deletions

diff --git a/third_party/nix/src/nix/upgrade-nix.cc b/third_party/nix/src/nix/upgrade-nix.cc
index b225aac2d725..9b060a7f195a 100644
--- a/third_party/nix/src/nix/upgrade-nix.cc
+++ b/third_party/nix/src/nix/upgrade-nix.cc
@@ -97,7 +97,7 @@ struct CmdUpgradeNix : MixDryRun, StoreCommand {
   }
 
   /* Return the profile in which Nix is installed. */
-  static Path getProfileDir(ref<Store> store) {
+  static Path getProfileDir(const ref<Store>& store) {
     Path where;
 
     for (auto& dir : tokenizeString<Strings>(getEnv("PATH"), ":")) {
@@ -143,7 +143,7 @@ struct CmdUpgradeNix : MixDryRun, StoreCommand {
   }
 
   /* Return the store path of the latest stable Nix. */
-  Path getLatestNix(ref<Store> store) {
+  Path getLatestNix(const ref<Store>& store) {
     // FIXME: use nixos.org?
     auto req = DownloadRequest(storePathsUrl);
     auto res = getDownloader()->download(req);