From 411111a3bc0e47520797106e1697aaa11631a101 Mon Sep 17 00:00:00 2001
From: Maximilian Bosch <maximilian@mbosch.me>
Date: Tue, 12 Jul 2022 11:22:35 +0200
Subject: [PATCH] Turn error for non-existant follows into a warning

---
 src/libexpr/flake/flake.cc | 5 ++---
 tests/flakes.sh            | 2 +-
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index b97780a9c..c59a42d56 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -373,8 +373,7 @@ LockedFlake lockFlake(
         {
             debug("computing lock file node '%s'", printInputPath(inputPathPrefix));
 
-            auto overrides2 = overrides;
-            for (auto & [inputPath, inputOverride] : overrides2) {
+            for (auto [inputPath, inputOverride] : overrides) {
                 auto inputPath2(inputPath);
                 auto follow = inputPath2.back();
                 inputPath2.pop_back();
@@ -388,7 +387,7 @@ LockedFlake lockFlake(
                             root.append(".inputs.");
                         }
                     }
-                    throw Error(
+                    warn(
                         "%s has a `follows'-declaration for a non-existant input %s!",
                         root,
                         follow
diff --git a/tests/flakes.sh b/tests/flakes.sh
index 868c410f4..9087e1978 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -877,4 +877,4 @@ EOF
 
 git -C $flakeFollowsA add flake.nix
 
-nix flake lock $flakeFollowsA 2>&1 | grep "error: B has a \`follows'-declaration for a non-existant input invalid!"
+nix flake lock $flakeFollowsA 2>&1 | grep "warning: B has a \`follows'-declaration for a non-existant input invalid!"