Xonsh adds unwanted entries to PATH

[amacfie]

Describe the bug

Using xonsh in a nix-shell environment can override the Python interpreter, which is a problem if the environment is supposed to use a specific one.

Steps To Reproduce

sudo docker run -ti --rm nixos/nix bash
nix-channel --update

Then create shell.nix containing

{ pkgs ? import <nixpkgs> {} }:

pkgs.mkShell {
  packages = [
    (pkgs.python311.withPackages (ps: [
      ps.requests
    ]))
    pkgs.xonsh
  ];
}

Then inside xonsh, a different Python interpreter is used:

nix-shell
xonsh
python -c "import requests"  # -> ModuleNotFoundError: No module named 'requests'

Expected behavior

Running xonsh should not modify the PATH such that a different python executable is used. In the above, when we run python we should get the requests library.

Workarounds

Running $PATH.pop(0) removes the problematic PATH entry but this is pretty hacky.

Notify maintainers

@vrthra

Metadata

Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.

[user@system:~]$ nix-shell -p nix-info --run "nix-info -m"
 - system: `"x86_64-linux"`
 - host os: `Linux 6.1.35`
 - multi-user?: `yes`
 - sandbox: `no`
 - version: `nix-env (Nix) 2.17.0`
 - channels(root): `"nixpkgs"`
 - nixpkgs: `/nix/var/nix/profiles/per-user/root/channels/nixpkgs`

[charmoniumQ]

I think the recommended way to do this is to add an override to xonsh.

      (pkgs.xonsh.override {
        extraPackages = pypkgs: ps: [ ps.requests ];
      })

See #240246

[amacfie]

I think the recommended way to do this is to add an override to xonsh.

      (pkgs.xonsh.override {
        extraPackages = pypkgs: ps: [ ps.requests ];
      })

See #240246

That's a help but if I launch a nested xonsh by running xonsh -i in xonsh, the extra packages are gone.

I've removed these unwanted PATH entries by doing, e.g. in configuration.nix:

programs.xonsh.enable = true;
programs.xonsh.package = pkgs.xonsh.override {
  xonsh-unwrapped = pkgs.xonsh-unwrapped.overridePythonAttrs (
    old: {dontWrapPythonPrograms = true;}
  );
};

Everything works fine so far.

[amacfie]

@SamLukeYes since your PR was reverted is this issue still fixed?

ETA: looks ok but if anyone still has dontWrapPythonPrograms = true in their config they should probably remove it before upgrading xonsh or they may get #301444.

[SamLukeYes]

@SamLukeYes since your PR was reverted is this issue still fixed?

ETA: looks ok but if anyone still has dontWrapPythonPrograms = true in their config they should probably remove it before upgrading xonsh or they may get #301444.

To make it clear, dontWrapPythonPrograms = true was reapplied in #302385, while reverting #297628.

[SamLukeYes]

Oops, it seems we have re-introduced this issue in #314728