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/libstore/crypto.cc b/third_party/nix/src/libstore/crypto.cc
index 2fbc30fb3161..90580b8dc902 100644
--- a/third_party/nix/src/libstore/crypto.cc
+++ b/third_party/nix/src/libstore/crypto.cc
@@ -104,12 +104,12 @@ PublicKeys getDefaultPublicKeys() {
 
   // FIXME: filter duplicates
 
-  for (auto s : settings.trustedPublicKeys.get()) {
+  for (const auto& s : settings.trustedPublicKeys.get()) {
     PublicKey key(s);
     publicKeys.emplace(key.name, key);
   }
 
-  for (auto secretKeyFile : settings.secretKeyFiles.get()) {
+  for (const auto& secretKeyFile : settings.secretKeyFiles.get()) {
     try {
       SecretKey secretKey(readFile(secretKeyFile));
       publicKeys.emplace(secretKey.name, secretKey.toPublicKey());