From ebf222a86885a1d46db1b5cce5afcd37d2effbe8 Mon Sep 17 00:00:00 2001
From: Alberto Donato <alberto.donato@gmail.com>
Date: Tue, 29 Oct 2024 15:21:55 +0100
Subject: [PATCH] Pass nix-ld related variables by default in pass_env (fixes
 #3425)

---
 docs/changelog/3425.doc.rst           | 3 +++
 docs/config.rst                       | 8 ++++++++
 src/tox/tox_env/api.py                | 8 +++++++-
 tests/session/cmd/test_show_config.py | 4 +++-
 4 files changed, 21 insertions(+), 2 deletions(-)
 create mode 100644 docs/changelog/3425.doc.rst

diff --git a/docs/changelog/3425.doc.rst b/docs/changelog/3425.doc.rst
new file mode 100644
index 000000000..35fa8fd5f
--- /dev/null
+++ b/docs/changelog/3425.doc.rst
@@ -0,0 +1,3 @@
+Pass ``NIX_LD`` and ``NIX_LD_LIBRARY_PATH`` variables by default in ``pass_env`` to make generic binaries work under Nix/NixOS.
+
+- by :user:`albertodonato`
diff --git a/docs/config.rst b/docs/config.rst
index 81731da67..06e140d5f 100644
--- a/docs/config.rst
+++ b/docs/config.rst
@@ -534,6 +534,14 @@ Base options
             - ✅
             - ✅
             - ✅
+        *   - NIX_LD*
+            - ✅
+            - ✅
+            - ❌
+        *   - NIX_LD_LIBRARY_PATH
+            - ✅
+            - ✅
+            - ❌
 
 
 
diff --git a/src/tox/tox_env/api.py b/src/tox/tox_env/api.py
index bdf4a0b0f..ddb6c3c14 100644
--- a/src/tox/tox_env/api.py
+++ b/src/tox/tox_env/api.py
@@ -236,7 +236,13 @@ def _default_pass_env(self) -> list[str]:  # noqa: PLR6301
                 ],
             )
         else:  # pragma: win32 no cover
-            env.append("TMPDIR")  # temporary file location
+            env.extend(
+                [
+                    "TMPDIR",  # temporary file location
+                    "NIX_LD",  # nix-ld loader
+                    "NIX_LD_LIBRARY_PATH",  # nix-ld library path
+                ],
+            )
         return env
 
     def setup(self) -> None:
diff --git a/tests/session/cmd/test_show_config.py b/tests/session/cmd/test_show_config.py
index 370b91f65..5a2e9b637 100644
--- a/tests/session/cmd/test_show_config.py
+++ b/tests/session/cmd/test_show_config.py
@@ -126,7 +126,9 @@ def test_pass_env_config_default(tox_project: ToxProjectCreator, stdout_is_atty:
         + ["CPPFLAGS", "CURL_CA_BUNDLE", "CXX", "FORCE_COLOR", "HOME", "LANG"]
         + ["LANGUAGE", "LDFLAGS", "LD_LIBRARY_PATH"]
         + (["MSYSTEM"] if is_win else [])
-        + ["NETRC", "NO_COLOR"]
+        + ["NETRC"]
+        + (["NIX_LD", "NIX_LD_LIBRARY_PATH"] if not is_win else [])
+        + ["NO_COLOR"]
         + (["NUMBER_OF_PROCESSORS", "PATHEXT"] if is_win else [])
         + ["PIP_*", "PKG_CONFIG", "PKG_CONFIG_PATH", "PKG_CONFIG_SYSROOT_DIR"]
         + (["PROCESSOR_ARCHITECTURE"] if is_win else [])