From 64a69b40548f609a760b19f6b31d80e58aa49e3b Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 16 Nov 2022 14:21:07 +0100
Subject: [PATCH] Fix dirOf on the root of a flake

---
 src/libexpr/primops.cc | 2 +-
 tests/flakes/common.sh | 2 ++
 tests/flakes/flakes.sh | 3 +++
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index aaac98aab..19530d896 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1521,7 +1521,7 @@ static void prim_dirOf(EvalState & state, const PosIdx pos, Value * * args, Valu
     state.forceValue(*args[0], pos);
     if (args[0]->type() == nPath) {
         auto path = args[0]->path();
-        v.mkPath(path.parent());
+        v.mkPath(path.path.isRoot() ? path : path.parent());
     } else {
         auto path = state.coerceToString(pos, *args[0], context, false, false);
         auto dir = dirOf(*path);
diff --git a/tests/flakes/common.sh b/tests/flakes/common.sh
index c333733c2..67adf80ff 100644
--- a/tests/flakes/common.sh
+++ b/tests/flakes/common.sh
@@ -23,6 +23,8 @@ writeSimpleFlake() {
 
     # To test "nix flake init".
     legacyPackages.x86_64-linux.hello = import ./simple.nix;
+
+    parent = builtins.dirOf ./.;
   };
 }
 EOF
diff --git a/tests/flakes/flakes.sh b/tests/flakes/flakes.sh
index fc5cd3b03..17ac4451b 100644
--- a/tests/flakes/flakes.sh
+++ b/tests/flakes/flakes.sh
@@ -121,6 +121,9 @@ nix build -o $TEST_ROOT/result --expr "(builtins.getFlake \"$flake1Dir\").packag
 # 'getFlake' on a locked flakeref should succeed even in pure mode.
 nix build -o $TEST_ROOT/result --expr "(builtins.getFlake \"git+file://$flake1Dir?rev=$hash2\").packages.$system.default"
 
+# Regression test for dirOf on the root of the flake.
+[[ $(nix eval --json flake1#parent) = '"/"' ]]
+
 # Building a flake with an unlocked dependency should fail in pure mode.
 (! nix build -o $TEST_ROOT/result flake2#bar --no-registries)
 (! nix build -o $TEST_ROOT/result flake2#bar --no-use-registries)