fix(3p/nix): Update for usage of new attribute set API r/802

The new attribute set API uses the iterators of the btree_map
directly. This requires changes in various files because the internals
of libexpr are very entangled.

This code runs and compiles, but there is a bug causing empty
attribute sets to be assigned incorrectly.

1 files changed, 2 insertions, 2 deletions

diff --git a/third_party/nix/src/nix-env/user-env.cc b/third_party/nix/src/nix-env/user-env.cc
index adff263ff4cd..21e7d42e8845 100644
--- a/third_party/nix/src/nix-env/user-env.cc
+++ b/third_party/nix/src/nix-env/user-env.cc
@@ -129,11 +129,11 @@ bool createUserEnv(EvalState& state, DrvInfos& elems, const Path& profile,
   DLOG(INFO) << "evaluating user environment builder";
   state.forceValue(topLevel);
   PathSet context;
-  Attr& aDrvPath(*topLevel.attrs->find(state.sDrvPath));
+  Attr& aDrvPath(topLevel.attrs->find(state.sDrvPath)->second);
   Path topLevelDrv =
       state.coerceToPath(aDrvPath.pos != nullptr ? *(aDrvPath.pos) : noPos,
                          *(aDrvPath.value), context);
-  Attr& aOutPath(*topLevel.attrs->find(state.sOutPath));
+  Attr& aOutPath(topLevel.attrs->find(state.sOutPath)->second);
   Path topLevelOut =
       state.coerceToPath(aOutPath.pos != nullptr ? *(aOutPath.pos) : noPos,
                          *(aOutPath.value), context);