Python: withPackages and overrides does not result in correct passthru

[adisbladis]

Issue description

Using withPackages together with overrides currently does not work as expected.
Overrides does not propagate to withPackages.

Steps to reproduce

We can demonstrate this easily in the repl:

This works exactly as expected

nix-repl> (python3.override { packageOverrides=(self: super: { requests="hello"; }); }).passthru.pkgs.requests  
"hello"

This does not:

nix-repl> ((python3.override { packageOverrides=(self: super: { requests="hello"; }); }).withPackages(ps: [ps.requests])).passthru.pkgs.requests
«derivation /nix/store/qfnz62wvq8xbmf6zldxqfa205rklhwmv-python3.7-requests-2.21.0.drv»

I would expect the second case to also evaluate to my overriden package.

Technical details

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

cc @FRidh

[FRidh]

See "9.14.2.2.1.2. Overriding Python packages" in the Nixpkgs manual, rewritten as

with import <nixpkgs> {};

(let
  python = let
    packageOverrides = self: super: {
      foo = super.numpy.overridePythonAttrs(old: rec {
        name = "foo";
      });
    };
  in pkgs.python3.override {inherit packageOverrides;};

in python.withPackages(ps: [ps.foo])).env

The composition does function, however, the passthru seems to be incorrect. Just replace .env with .passthru.pkgs.foo .

[FRidh]

Using the following solves the issue:

with import <nixpkgs> {};

(let
  python = let
    packageOverrides = self: super: {
      foo = super.numpy.overridePythonAttrs(old: rec {
        name = "foo";
      });
    };
  in pkgs.python3.override {inherit packageOverrides; self = python;};

in python.withPackages(ps: [ps.foo])).passthru.pkgs.foo

Note the self = python.

[FRidh]

I've updated the example in f1ff85e. There's not much else I think we can do here.

[adisbladis]

Ok, updating the example is good enough :)
Thanks

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/python3-override-for-bluezsupport-not-working/36042/7

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/python3-override-for-bluezsupport-not-working/36042/8