nix flake archive: Skip relative path inputs

Fixes NixOS#12438.

Author: edolstra

src/nix/flake.cc

@@ -1090,12 +1090,14 @@ struct CmdFlakeArchive : FlakeCommand, MixJSON, MixDryRun
             nlohmann::json jsonObj2 = json ? json::object() : nlohmann::json(nullptr);
             for (auto & [inputName, input] : node.inputs) {
                 if (auto inputNode = std::get_if<0>(&input)) {
+                    if ((*inputNode)->lockedRef.input.isRelative())
+                        continue;
                     auto storePath =
                         dryRun
                         ? (*inputNode)->lockedRef.input.computeStorePath(*store)
                         : (*inputNode)->lockedRef.input.fetchToStore(store).first;
                     if (json) {
-                        auto& jsonObj3 = jsonObj2[inputName];
+                        auto & jsonObj3 = jsonObj2[inputName];
                         jsonObj3["path"] = store->printStorePath(storePath);
                         sources.insert(std::move(storePath));
                         jsonObj3["inputs"] = traverse(**inputNode);

tests/functional/flakes/relative-paths.sh

@@ -76,6 +76,9 @@ if ! isTestOnNixOS; then
 fi
 (! grep narHash "$subflake2/flake.lock")
 
+# Test `nix flake archive` with relative path flakes.
+nix flake archive --json "$rootFlake"
+
 # Test circular relative path flakes. FIXME: doesn't work at the moment.
 if false; then