From 56c90fef8bca0f4bc3f0e530f789326643fc2fa7 Mon Sep 17 00:00:00 2001
From: warren2k <846021+warren2k@users.noreply.github.com>
Date: Sat, 22 Jun 2024 11:05:03 -0400
Subject: [PATCH] fix: wrapped nix

Co-authored-by: Shahar "Dawn" Or <mightyiampresence@gmail.com>
---
 flake.nix                | 25 +++++++++++++++++++++----
 src/expression/driver.rs |  2 +-
 src/repl/driver.rs       |  2 +-
 3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/flake.nix b/flake.nix
index d6183a7..2690451 100644
--- a/flake.nix
+++ b/flake.nix
@@ -21,13 +21,30 @@
     nixpkgs,
     treefmt-nix,
   }: let
-    inherit (nixpkgs.lib) optional mkForce;
+    inherit (nixpkgs.lib) getExe optional mkForce;
   in
     flake-utils.lib.eachDefaultSystem (system: let
       pkgs = nixpkgs.legacyPackages.${system};
       toolchain = fenix.packages.${system}.stable.completeToolchain;
       craneLib = crane.lib.${system}.overrideToolchain toolchain;
-      NIX_BIN_DIR = "${nix.packages.${system}.nix}/bin";
+      nixDrv = nix.packages.${system}.nix;
+
+      isolatedNix = postfix:
+        pkgs.symlinkJoin {
+          name = "isolated-nix${postfix}";
+          paths = [nixDrv];
+          nativeBuildInputs = [pkgs.makeWrapper];
+          postBuild = ''
+            wrapProgram $out/bin/nix${postfix} \
+              --set NIX_CONF_DIR /dev/null \
+              --set NIX_USER_CONF_FILES /dev/null \
+              --unset NIX_CONFIG
+          '';
+          meta.mainProgram = "nix${postfix}";
+        };
+
+      NIX_CMD_PATH = getExe (isolatedNix "");
+      NIX_INSTANTIATE_CMD_PATH = getExe (isolatedNix "-instantiate");
 
       commonArgs = {
         src = craneLib.cleanCargoSource (craneLib.path ./.);
@@ -46,7 +63,7 @@
       packages.default = craneLib.buildPackage (
         commonArgs
         // {
-          inherit cargoArtifacts NIX_BIN_DIR;
+          inherit cargoArtifacts NIX_CMD_PATH NIX_INSTANTIATE_CMD_PATH;
           nativeCheckInputs = [pkgs.nix];
           # 1. integration tests execute `nix`, which fails creating `/nix/var`
           # 2. integration tests require `/dev/ptmx`
@@ -55,7 +72,7 @@
       );
 
       devShells.default = craneLib.devShell {
-        inherit NIX_BIN_DIR;
+        inherit NIX_CMD_PATH NIX_INSTANTIATE_CMD_PATH;
         inputsFrom = [self.packages.${system}.default];
         packages = [
           toolchain
diff --git a/src/expression/driver.rs b/src/expression/driver.rs
index 538fab3..18fe91b 100644
--- a/src/expression/driver.rs
+++ b/src/expression/driver.rs
@@ -71,7 +71,7 @@ impl ExpressionDriver {
     }
 
     async fn spawn_nix(&mut self, example: ExpressionExample) {
-        let task = tokio::process::Command::new(concat!(env!("NIX_BIN_DIR"), "/nix-instantiate"))
+        let task = tokio::process::Command::new(env!("NIX_INSTANTIATE_CMD_PATH"))
             .args(["--expr", "--eval"])
             .arg(example.expression)
             .output();
diff --git a/src/repl/driver.rs b/src/repl/driver.rs
index 4e8b1cb..951a14c 100644
--- a/src/repl/driver.rs
+++ b/src/repl/driver.rs
@@ -135,7 +135,7 @@ impl ReplDriver {
     async fn spawn(&mut self, id: ExampleId) {
         let (read_output, write_output) = nix::unistd::pipe().unwrap();
 
-        let child = tokio::process::Command::new(concat!(env!("NIX_BIN_DIR"), "/nix"))
+        let child = tokio::process::Command::new(env!("NIX_CMD_PATH"))
             // even though a single `--quiet` would normally disable the pre-prompt message
             // (at the time of writing `Nix 2.21.1`), two seem to be necessary here.
             .args(["repl", "--quiet", "--quiet"])