Can't set environment variables in `shellFor` any more

[michaelpj]

Describe the bug

Normally in nix derivations extra attributes get set as environment variables, so you could do e.g.

shellFor {
   FOO = "bar";
}

and it would set FOO in the shell. Since some point recently this started saying:

error: The option `shell.FOO' does not exist. Definition values:                                                                                                                                                                              
- In `<unknown-file>': 1   

Expected behavior

The extra attribute should just be passed through to the final derivation. Unless this is intentional.

[hamishmack]

shellFor args are now checked against modules/shell.nix. I could not find a way to allow arbitrary options.

To set an environment variable you can use:

p.shellFor {
  shellHook = ''
    export FOO="bar"
  '';
}

or

(p.shellFor {}).overrideAttrs {
   FOO = "bar";
}

Keep this issue open because we need to either:

• Make the way work again
• Add this change to change log and docs