From 77a9745d7ac675883fdbe8c448b5b94904cd2d2a Mon Sep 17 00:00:00 2001
From: Daiderd Jordan <daiderd@gmail.com>
Date: Sat, 28 Jul 2018 15:52:36 +0200
Subject: [PATCH] nix: don't use /tmp for the tests on darwin

Unlike on linux these are not namespaced per user so this will cause
build failures if /tmp/nix-test was not removed by a previous build if
the nixbld user id doesn't match by accident. Nix already creates a
unique tempdir for builds so we can use that instead.

Fixes #44172
---
 pkgs/tools/package-management/nix/default.nix | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/pkgs/tools/package-management/nix/default.nix b/pkgs/tools/package-management/nix/default.nix
index 07c130f1cb3..5c8341941ed 100644
--- a/pkgs/tools/package-management/nix/default.nix
+++ b/pkgs/tools/package-management/nix/default.nix
@@ -71,7 +71,9 @@ let
     doInstallCheck = true; # not cross
 
     # socket path becomes too long otherwise
-    preInstallCheck = lib.optional stdenv.isDarwin "export TMPDIR=/tmp";
+    preInstallCheck = lib.optional stdenv.isDarwin ''
+      export TMPDIR=$NIX_BUILD_TOP
+    '';
 
     separateDebugInfo = stdenv.isLinux;