From ffc8ec5c9ae6cf7b3bb95866432e30e46e7cc731 Mon Sep 17 00:00:00 2001
From: Malo Bourgon <mbourgon@gmail.com>
Date: Sun, 14 Aug 2022 14:04:20 -0700
Subject: [PATCH] Add .nix-defexpr to NIX_PATH the way the NixOS module does

---
 modules/nix/default.nix           | 24 ++++++++++++++----------
 modules/system/checks.nix         |  8 +++++---
 pkgs/darwin-installer/default.nix |  4 ++--
 3 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/modules/nix/default.nix b/modules/nix/default.nix
index c816648a..6b32caa7 100644
--- a/modules/nix/default.nix
+++ b/modules/nix/default.nix
@@ -378,7 +378,6 @@ in
             # Include default path <darwin-config>.
             { darwin-config = "${config.environment.darwinConfig}"; }
             "/nix/var/nix/profiles/per-user/root/channels"
-            "$HOME/.nix-defexpr/channels"
           ];
         description = ''
           The default Nix expression search path, used by the Nix
@@ -734,21 +733,26 @@ in
       (mkIf (config.system.stateVersion > 3) (mkOrder 1200
       [ { darwin-config = "${config.environment.darwinConfig}"; }
         "/nix/var/nix/profiles/per-user/root/channels"
-        "$HOME/.nix-defexpr/channels"
       ]))
     ];
 
     # Set up the environment variables for running Nix.
     environment.variables = cfg.envVars // { NIX_PATH = cfg.nixPath; };
 
-    # Unreladed to use in NixOS module
-    environment.extraInit = ''
-      # Set up secure multi-user builds: non-root users build through the
-      # Nix daemon.
-      if [ ! -w /nix/var/nix/db ]; then
-          export NIX_REMOTE=daemon
-      fi
-    '';
+    environment.extraInit =
+      ''
+        if [ -e "$HOME/.nix-defexpr/channels" ]; then
+          export NIX_PATH="$HOME/.nix-defexpr/channels''${NIX_PATH:+:$NIX_PATH}"
+        fi
+      '' +
+      # Not in NixOS module
+      ''
+        # Set up secure multi-user builds: non-root users build through the
+        # Nix daemon.
+        if [ ! -w /nix/var/nix/db ]; then
+            export NIX_REMOTE=daemon
+        fi
+      '';
 
     nix.nrBuildUsers = mkDefault (max 32 (if cfg.settings.max-jobs == "auto" then 0 else cfg.settings.max-jobs));
 
diff --git a/modules/system/checks.nix b/modules/system/checks.nix
index 2af25c8f..4ce69912 100644
--- a/modules/system/checks.nix
+++ b/modules/system/checks.nix
@@ -125,7 +125,9 @@ let
   '';
 
   nixPath = ''
-    darwinConfig=$(NIX_PATH=${concatStringsSep ":" config.nix.nixPath} nix-instantiate --find-file darwin-config) || true
+    nixPath=${concatStringsSep ":" config.nix.nixPath}:$HOME/.nix-defexpr/channels
+
+    darwinConfig=$(NIX_PATH=$nixPath nix-instantiate --find-file darwin-config) || true
     if ! test -e "$darwinConfig"; then
         echo "error: Changed <darwin-config> but target does not exist, aborting activation" >&2
         echo "Create ''${darwinConfig:-~/.nixpkgs/darwin-configuration.nix} or set environment.darwinConfig:" >&2
@@ -139,7 +141,7 @@ let
         exit 2
     fi
 
-    darwinPath=$(NIX_PATH=${concatStringsSep ":" config.nix.nixPath} nix-instantiate --find-file darwin) || true
+    darwinPath=$(NIX_PATH=$nixPath nix-instantiate --find-file darwin) || true
     if ! test -e "$darwinPath"; then
         echo "error: Changed <darwin> but target does not exist, aborting activation" >&2
         echo "Add the darwin repo as a channel or set nix.nixPath:" >&2
@@ -153,7 +155,7 @@ let
         exit 2
     fi
 
-    nixpkgsPath=$(NIX_PATH=${concatStringsSep ":" config.nix.nixPath} nix-instantiate --find-file nixpkgs) || true
+    nixpkgsPath=$(NIX_PATH=$nixPath nix-instantiate --find-file nixpkgs) || true
     if ! test -e "$nixpkgsPath"; then
         echo "error: Changed <nixpkgs> but target does not exist, aborting activation" >&2
         echo "Add a nixpkgs channel or set nix.nixPath:" >&2
diff --git a/pkgs/darwin-installer/default.nix b/pkgs/darwin-installer/default.nix
index cf1c7058..496aa4f0 100644
--- a/pkgs/darwin-installer/default.nix
+++ b/pkgs/darwin-installer/default.nix
@@ -145,13 +145,13 @@ stdenv.mkDerivation {
         env -i USER=john HOME=/Users/john bash -li -c 'echo $PATH'
         env -i USER=john HOME=/Users/john bash -li -c 'echo $PATH' | grep /Users/john/.nix-profile/bin:/run/current-system/sw/bin:/nix/var/nix/profiles/default/bin:/usr/local/bin:/usr/bin:/usr/sbin:/bin:/sbin
         env -i USER=john HOME=/Users/john bash -li -c 'echo $NIX_PATH'
-        env -i USER=john HOME=/Users/john bash -li -c 'echo $NIX_PATH' | grep darwin-config=/Users/john/.nixpkgs/darwin-configuration.nix:/nix/var/nix/profiles/per-user/root/channels:/Users/john/.nix-defexpr/channels
+        env -i USER=john HOME=/Users/john bash -li -c 'echo $NIX_PATH' | grep darwin-config=/Users/john/.nixpkgs/darwin-configuration.nix:/nix/var/nix/profiles/per-user/root/channels
 
         echo >&2 "checking zsh environment"
         env -i USER=john HOME=/Users/john zsh -l -c 'echo $PATH'
         env -i USER=john HOME=/Users/john zsh -l -c 'echo $PATH' | grep /Users/john/.nix-profile/bin:/run/current-system/sw/bin:/nix/var/nix/profiles/default/bin:/usr/local/bin:/usr/bin:/usr/sbin:/bin:/sbin
-        env -i USER=john HOME=/Users/john zsh -l -c 'echo $NIX_PATH' | grep darwin-config=/Users/john/.nixpkgs/darwin-configuration.nix:/nix/var/nix/profiles/per-user/root/channels:/Users/john/.nix-defexpr/channels
         env -i USER=john HOME=/Users/john zsh -l -c 'echo $NIX_PATH'
+        env -i USER=john HOME=/Users/john zsh -l -c 'echo $NIX_PATH' | grep darwin-config=/Users/john/.nixpkgs/darwin-configuration.nix:/nix/var/nix/profiles/per-user/root/channels
 
         echo >&2 ok
         exit