Only provide builtin.{getFlake,fetchClosure} is the corresponding experimental feature is enabled

This allows writing fallback code like

  if builtins ? fetchClosure then
    builtins.fetchClose { ... }
  else
    builtins.storePath ...

1 files changed, 1 insertions, 0 deletions

diff --git a/src/nix/main.cc b/src/nix/main.cc
index 9bc6c15fa..6198681e7 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -289,6 +289,7 @@ void mainWrapped(int argc, char * * argv)
     }
 
     if (argc == 2 && std::string(argv[1]) == "__dump-builtins") {
+        settings.experimentalFeatures = {Xp::Flakes, Xp::FetchClosure};
         evalSettings.pureEval = false;
         EvalState state({}, openStore("dummy://"));
         auto res = nlohmann::json::object();