From 6286272371434dc597da793417787ecd3cb14cc9 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 28 May 2020 12:13:13 +0200
Subject: [PATCH] nixpkgsFlakeRef(): Use locked nixpkgs

---
 src/nix/installables.cc | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/nix/installables.cc b/src/nix/installables.cc
index 21fd54f64..fde1ca7aa 100644
--- a/src/nix/installables.cc
+++ b/src/nix/installables.cc
@@ -503,9 +503,12 @@ FlakeRef InstallableFlake::nixpkgsFlakeRef() const
 {
     auto lockedFlake = getLockedFlake();
 
-    auto nixpkgsInput = lockedFlake->flake.inputs.find("nixpkgs");
-    if (nixpkgsInput != lockedFlake->flake.inputs.end()) {
-        return std::move(nixpkgsInput->second.ref);
+    auto nixpkgsInput = lockedFlake->lockFile.root->inputs.find("nixpkgs");
+    if (nixpkgsInput != lockedFlake->lockFile.root->inputs.end()) {
+        if (auto lockedNode = std::dynamic_pointer_cast<const flake::LockedNode>(nixpkgsInput->second)) {
+            debug("using nixpkgs flake '%s'", lockedNode->lockedRef);
+            return std::move(lockedNode->lockedRef);
+        }
     }
 
     return Installable::nixpkgsFlakeRef();