From 9f73309ff19bda94d6bcbe77dcd72c1c65a9f37d Mon Sep 17 00:00:00 2001
From: NAHO <90870942+trueNAHO@users.noreply.github.com>
Date: Tue, 1 Oct 2024 10:35:34 +0200
Subject: [PATCH] modules: pre-commit: make pkgs.buildEnv composable

Passing a git-hooks.lib.<SYSTEM>.run derivation as a path to
pkgs.buildEnv results in the following error due to derivations with an
empty file being treated differently from derivations with an empty
directory:

    The store path <TARGET> is a file and can't be merged into an
    environment using pkgs.buildEnv!

Since Nixpkgs rejected explicitly handling derivations with an empty
file in pkgs.buildEnv [1], affected derivations should transition from
'touch $out' to 'mkdir $out' to be pkgs.buildEnv composable.

This change replaces 'touch $out' with 'mkdir $out' and makes the
following command work:

    nix \
      build \
      --expr '
        let
          flake = builtins.getFlake (toString ./.);
          system = builtins.currentSystem;
        in
          flake.inputs.nixpkgs.legacyPackages.${system}.buildEnv {
            name = "";
            paths = [(flake.outputs.lib.${system}.run {src = ./.;})];
          }
      ' \
      --impure

[1]: https://github.com/NixOS/nixpkgs/pull/325140

Link: https://github.com/cachix/git-hooks.nix/pull/498
---
 modules/pre-commit.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/modules/pre-commit.nix b/modules/pre-commit.nix
index a5fae075..1a1701dd 100644
--- a/modules/pre-commit.nix
+++ b/modules/pre-commit.nix
@@ -78,7 +78,7 @@ let
       fi
       exitcode=$?
       git --no-pager diff --color
-      touch $out
+      mkdir $out
       [ $? -eq 0 ] && exit $exitcode
     '';