Tarball trees: Propagate lastModified

This makes them behave consistently with GitHub/GitLab flakes.

1 files changed, 4 insertions, 1 deletions

diff --git a/src/libfetchers/tarball.cc b/src/libfetchers/tarball.cc
index 107d38e92..e3a41e75e 100644
--- a/src/libfetchers/tarball.cc
+++ b/src/libfetchers/tarball.cc
@@ -232,7 +232,7 @@ struct CurlInputScheme : InputScheme
         if (type != inputType()) return {};
 
         // FIXME: some of these only apply to TarballInputScheme.
-        std::set<std::string> allowedNames = {"type", "url", "narHash", "name", "unpack", "rev", "revCount"};
+        std::set<std::string> allowedNames = {"type", "url", "narHash", "name", "unpack", "rev", "revCount", "lastModified"};
         for (auto & [name, value] : attrs)
             if (!allowedNames.count(name))
                 throw Error("unsupported %s input attribute '%s'", *type, name);
@@ -310,6 +310,9 @@ struct TarballInputScheme : CurlInputScheme
             input = immutableInput;
         }
 
+        if (result.lastModified && !input.attrs.contains("lastModified"))
+            input.attrs.insert_or_assign("lastModified", uint64_t(result.lastModified));
+
         return {result.tree.storePath, std::move(input)};
     }
 };