From cbedb8e19a0c85747526900f184d368d4b36cdaa Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 13 Jun 2025 15:21:31 +0200
Subject: [PATCH] Fix broken fetchToStore() caching on unlocked inputs

---
 src/libfetchers/fetchers.cc       | 2 +-
 tests/functional/flakes/flakes.sh | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/libfetchers/fetchers.cc b/src/libfetchers/fetchers.cc
index 6d73daa1a..7ab1f567a 100644
--- a/src/libfetchers/fetchers.cc
+++ b/src/libfetchers/fetchers.cc
@@ -355,7 +355,7 @@ std::pair<ref<SourceAccessor>, Input> Input::getAccessorUnchecked(ref<Store> sto
 
     assert(!accessor->getFingerprint(CanonPath::root));
 
-    if (auto fingerprint = getFingerprint(store))
+    if (auto fingerprint = result.getFingerprint(store))
         accessor->setFingerprint(*fingerprint);
 
     return {accessor, std::move(result)};
diff --git a/tests/functional/flakes/flakes.sh b/tests/functional/flakes/flakes.sh
index e335fe6f3..51f1909a2 100755
--- a/tests/functional/flakes/flakes.sh
+++ b/tests/functional/flakes/flakes.sh
@@ -112,6 +112,12 @@ nix build -o "$TEST_ROOT/result" "git+file://$flake1Dir#default"
 nix build -o "$TEST_ROOT/result" "$flake1Dir?ref=HEAD#default"
 nix build -o "$TEST_ROOT/result" "git+file://$flake1Dir?ref=HEAD#default"
 
+# Check that the fetcher cache works.
+if [[ $(nix config show lazy-trees) = false ]]; then
+    nix build -o "$TEST_ROOT/result" "git+file://$flake1Dir?ref=HEAD#default" -vvvvv 2>&1 | grepQuietInverse "source path.*is uncacheable"
+    nix build -o "$TEST_ROOT/result" "git+file://$flake1Dir?ref=HEAD#default" -vvvvv 2>&1 | grepQuiet "store path cache hit"
+fi
+
 # Check that relative paths are allowed for git flakes.
 # This may change in the future once git submodule support is refined.
 # See: https://discourse.nixos.org/t/57783 and #9708.